Tankless info from consumer reports, Tankless...Bahhhhh

[nhmaster]

This is out of Consumer Reports.

Heating water accounts for up to 30 percent of the average home's energy budget. Some makers of gas-fired tankless water heaters claim their products can cut your energy costs up to half over regular storage heaters. So is it time to switch?

Probably not. Gas tankless water heaters, which use high-powered burners to quickly heat water as it runs through a heat exchanger, were 22 percent more energy efficient on average than the gas-fired storage-tank models in our tests. That translates into a savings of around $70 to $80 per year, based on 2008 national energy costs. But because they cost much more than storage water heaters, it can take up to 22 years to break even—longer than the 20-year life of many models. Moreover, our online poll of 1,200 readers revealed wide variations in installation costs, energy savings, and satisfaction.

With the help of an outside lab, we pitted Takagi and Noritz gas-fired tankless water heaters against three storage water heaters. EvenWe didn't test electric tankless heaters because many can't deliver hot water fast enough to replace a conventional water heater if ground*water is cold. in areas with warm groundwater, most homeowners would need to upgrade their electrical service to power a whole-house tankless model.

Our tests simulated daily use of 76 to 78 gallons of hot water. That's the equivalent of taking three showers, washing one laun*dry load, running the dishwasher once (six cycles), and turning on the faucet nine times, for a total of 19 draws. While that's considered heavy use compared with the standard Department of Energy test, we think it more accurately represents an average family's habits. We also ran more than 45,000 gallons of very hard water through a tanked model and a Rinnai tankless model to simulate about 11 years of regular use.

Here's what else we found:

Water runs hot and cold
Manufacturers of tankless water heaters are fond of touting their products' ability to provide an endless amount of hot water. But inconsistent water temperatures were a common complaint among our poll respondents. When you turn on the faucet, tankless models feed in some cold water to gauge how big a temperature rise is needed. If there's cool water lingering in your pipes, you'll receive a momentary "cold-water sandwich" between the old and new hot water. And a tankless water heater's burner might not ignite when you try to get just a trickle of hot water for, say, shaving.

Nor do tankless water heaters deliver hot water instantaneously. It takes time to heat the water to the target temperature, and just like storage water heaters, any cold water in the pipes needs to be pushed out. And tankless models' electric controls mean you'll also lose hot water during a power outage.

Up-front costs are high
The tankless water heaters we tested cost $800 to $1,150, compared with $300 to $480 for the regular storage-tank types. Tankless models need electrical outlets for their fan and electronics, upgraded gas pipes, and a new ventilation system. That can bring average installation costs to $1,200, compared with $300 for storage-tank models.

Tankless units might need more care
During our long-term testing, an indicator on the tankless model warned of scale buildup. We paid $334 for special valves and a plumber to flush out the water heater with vinegar. Many industry pros recommend that tankless models be serviced once a year by a qualified technician. Calcium buildup can decrease efficiency, restrict water flow, and damage tankless models. Experts suggest installing a water softener if your water hardness is above 11 grains per gallon. Ignoring this advice can shorten your warranty.

Efficient storage models are pricey
We also tested the $1,400 Vertex, a high-efficiency storage water heater by A.O. Smith. The manufacturer claims its installation costs are similar to a regular storage model. But its high cost offsets much of the roughly $70 per year the Vertex will save you. Instead, we recommend buying a conventional storage water heater with a 9- or 12-year warranty. In previous tests, we found that those models generally had thicker insulation, bigger burners or larger heating elements, and better corrosion-fighting metal rods called anodes.

Posted: September 2008 — Consumer Reports Magazine issue: October 2008

So basically Consumer Reports is verifying pretty much everything those of us that have been screwing around with these things have been saying. Believe me, we have seen these products 25 years ago and had allthe same issues with them. In fact, most of those have long since been scrapped for more conventional heaters.

Indirect heaters use a boiler to heat a quantity of hot water. The storage tank is super insulated and has very very low standby loss. The recovery of these units if properly sized will allow you to virtually run hot water all day long.

[jimbo]

I am happy to see that article. There are people who love tankless, and more power to them. Sometimes, you are made to feel like a heretic or a luddite for opposing tankless.

I have always maintained that the ONLY advantage possible with a tankless is that MULTIPLE folks can take sequential showers. Or you can fill a large tub. These applications are where the 70% rule on tank heaters catches up with you. But for most homes, forget it . The payback time is LONG.

I can remember some places I stayed at in Hong Kong had tankless heaters...it was literally IN the shower....hanging right there on the wall. It put out HOT water, right away. I suspect it did not have a lot of the safeties that today's units do, so the water came on hot and stayed hot. It was great! I imagine that the space savings in small apartments, and saving on running all that hot water pipe everywhere....was the reason for using them. I don't remember, but I don't think there was anything but cold in the sinks.


I agree with CU's usage numbers. I keep spreadsheets of water usage in my condo comlex ( we have usage issues!). Over a couple of years data, our usage runs about 165 gallons per day, per unit. Now the units are a mix of 1 and 2 BR, one to 4 persons per unit ( occasionally 7 illegal aliens in one unit!). 2BR units have 2 baths, all units have DW and WM. So the data is blended. This number does not include landscape, which is on a separate meter.

[SewerRatz]

I recall when tankless first came out. Their huge claim to fame was that they been in use overseas for over 50 years. They fail to say the reason they been in use for that long over there is most places do not have room for a storage tank. Now Bradford White came out with a water heater that can deal with the high demand like filling a hot tub. A 25 gallon water heater puts out more hot water in the first hour than a standard 50 gallon. Here is the spec sheet. http://www.bradfordwhite.com/images/shared/pdfs/specsheets/115-B.pdf

[Ian Gills]

You are missing an important part of the space advantage in their use overseas.

Most countries use a tankless combination boiler that provides hot water for the faucets and hot water for the heating via radiators.

So they really are much better than the seperate water heater and furnace that you use here in the colonies and that I have, too, in my colonial home. In Great Britain, the combination tankless boilers are far smaller and they last just as long too.

The only drawback is that without forced air, most of these homes do not have AC but it is a colder climate anyway.

Worcester Bosch make the best tankless combination boilers in Europe.

Forced air heating solutions in Europe date back to the 1970s. They are considered extremely dated and (most of all) expensive to run.

[Ladiesman271]

Water runs hot and cold
Manufacturers of tankless water heaters are fond of touting their products' ability to provide an endless amount of hot water. But inconsistent water temperatures were a common complaint among our poll respondents. When you turn on the faucet, tankless models feed in some cold water to gauge how big a temperature rise is needed. If there's cool water lingering in your pipes, you'll receive a momentary "cold-water sandwich" between the old and new hot water. And a tankless water heater's burner might not ignite when you try to get just a trickle of hot water for, say, shaving.

Nor do tankless water heaters deliver hot water instantaneously. It takes time to heat the water to the target temperature, and just like storage water heaters, any cold water in the pipes needs to be pushed out. And tankless models' electric controls mean you'll also lose hot water during a power outage.




Glad that I have a pilot type tankless gas water heater. Instant ignition of gas burner to full on, no cold water sandwich, no electicity needed, and can be used when there is no power.

As far as that "trickle" test is concerned, I have never had that problem either. With 70 feet of insulated 1/2" pipe, it does take about 1 minute to get full temperature at the furthest outlet. About 30 seconds for warm water to get there.

I also needed the floor space that the old tank took up!


Tutorial on tankless water heaters - click here! (http://www.profitableplumbing.com/_wsn/page5.html)


.

[Cass]

Yup...this echos everything that has been mentioned here since they first started becoming popular...

[JAR8832]

They just had an episode of Ask This Old House on where the resident plumber replaced a tank heater with a tankless, showing the step by step process as if an experienced homeowner could tackle the project. They never explicitly said it was a DIY project, but they didn't explicitly advise against it either. And while they didn't verbally name the heater, the "Rennai" label was shown prominently during the install.

Of course, they also conveniently side stepped all of the issues discussed by the CR article and the plumber went so far as to suggest blanketly that anyone with a tank heater over 7 years old should replace it with a tankless, and implied that the savings in gas would definitley payback the increased upfront costs.

Way to go PBS with your unbaised, objective, sound advice.

[ArtM]

Well, I won't pay retail for a tankless ;) ... But, it may make sense for one of my layouts.

We have a family country place that is in need of a complete plumbing overhaul. We leave the heat on (moderately) all the time (winter) as we never know when someone may be dropping in to use the place for a day or week. Sometimes the place won't have visitors for a week or two - maybe even three. Then we may have a family get together with a houseful of people.

I dislike seeing the tank water heater going all the time the place sits empty. But, I really dislike taking cold showers - which is usually what happens when the tank heater can't handle so many people in a row.

Think the upfront expense might be worth it - for the hot shower if nothing else (yes, I'm usually the last guy in line).

[Fubar411]

Helped a buddy with his country place. We just put in a smaller electric water heater. Part of the instructions for starting the place up include flipping the breakers for the well and the WH. It is amazing how quickly a 40gal wh gets hot, even with just electricity.

[gregsauls]

Getting my Rinnia at cost plus was a benni.... add the US tax credit for 2009 as another benni. It all adds up to a good investment for me. YMMV.

[ArtM]

Helped a buddy with his country place. We just put in a smaller electric water heater. Part of the instructions for starting the place up include flipping the breakers for the well and the WH. It is amazing how quickly a 40gal wh gets hot, even with just electricity.

Makes sense, but one can't get very many back to back showers out of a 40 gal electric tank. At our place, after six or eight of us have been running through the mountains all day, we all would like to shower before evening cards and games. So I'm thinking tankless may have its place - even though it certainly isn't the answer for all hot water applications.

[Scuba_Dave]

I don't have gas to the house, so tankless wasn't an option
I need my 200a service for my Christmas display :eek:
We had a 30g oil fired that let loose
Oilman said to replace it would be $1900 - but it would be the last one I bought. Instead we went with a 95% efficient 50g electric model. I don't have a clamp meter, not sure how much it uses a month
With the cost of Oil (we have oil heat) it made sense

I'm going to add a solar hot water heater for summer use
I also want to add another tank to allow ground water to warm up before it enters the WH

I like the idea of tankless, but have just heard too many opposite opinions of how well (or not) that it works

[jadnashua]

If you mountain water is ice cold coming in the house in the winter, you will probably not be very happy with the tankless. Like a hand through a flame, a tankless can only heat so much (raise the temp), and the colder the source water, the colder the outlet.

[ArtM]

If you mountain water is ice cold coming in the house in the winter, you will probably not be very happy with the tankless. Like a hand through a flame, a tankless can only heat so much (raise the temp), and the colder the source water, the colder the outlet.

Good thought. Thanks for mentioning it. We've a well that has a pretty consistent temp summer or winter. Unsure what the temp of it is - but it isn't ice cold. We'll be out there next weekend. Think I'll measure the temp and find out what we're dealing with.

[Ladiesman271]

If you mountain water is ice cold coming in the house in the winter, you will probably not be very happy with the tankless. Like a hand through a flame, a tankless can only heat so much (raise the temp), and the colder the source water, the colder the outlet.


I disagree. Most tankless heaters do have a thermostat. My water temperature coming in is now 40 degrees, and my older 125,000 BTU tankless has no problem at all delivering 125 degree hot water to the last fixture.

I admit that I can not take three showers, do laundry, and use the dishwasher all at the same time. Then again, I have never needed to do that either. I don't think that the cold water can maintain pressure if I have all those units on at the same time either!

[chris8796]

I disagree. Most tankless heaters do have a thermostat. My water temperature coming in is now 40 degrees, and my older 125,000 BTU tankless has no problem at all delivering 125 degree hot water to the last fixture.

Crunching the numbers, it looks like you can heat ~2.2 gal/min with a 85 F temperature rise. So your right at the edge of your capacity. But, overall I think this would be a good application for tankless WH.

[rwcarpenter]

I noticed some whole house 4 bath electric tankless require 300A service...so your 200A would not be enough for those (3x60A). I have decided that the ones that work on 2x50 and 2x60 circuits would not be all that great due to my cold ground water (very cold deep well water).

I am however considering a couple of 30A tankless as boosters for a couple of my showers (or one 40 or 50 amp one since they are close and on same line). Its a long run and takes longer to get really hot water from other end of house than to take a shower, so its either take a lukewarm or cool bath or wait. What do you guys think of them for that application (that is localized boost heating)?

[Ladiesman271]

Crunching the numbers, it looks like you can heat ~2.2 gal/min with a 85 F temperature rise. So your right at the edge of your capacity. But, overall I think this would be a good application for tankless WH.



In reality I am not at the edge of my hot water capacity. You are accurate in that my gas water heater is rated at 2.09 gallons per minute @ a 90 degree temperature rise. That is pretty much identical to your calculation.

This morning I measured the water consumption while I was taking a shower. With everything set for a normal shower, I used about 1 gallon per minute of water during the shower. About 1/3 of that water was cold water (40 degree temperature).

So, the way that I see it I have plenty of water heating capacity to spare. The use of about 2/3 of a gallon per minute of hot water during a typical shower does not strain the heater at all.

[Ladiesman271]

I noticed some whole house 4 bath electric tankless require 300A service...so your 200A would not be enough for those (3x60A). I have decided that the ones that work on 2x50 and 2x60 circuits would not be all that great due to my cold ground water (very cold deep well water).





I have my doubts about the use of a central tankless powered by electricity. Some utilities do not permit them to be used due to the heavy peak power demands they require when they are in use.

For central electric, I would go with a tank type water heater.

[Dana]

That CU article was more than just annoyingly bad- it's downright disinformational!

In reality, if you use less than 60 gallons of water/day, your tank HW heater will perform LOWER than it did in an EF test (and far lower than the high-volume test the CU folks performed.)

Similarly, if the bulk of your water is a gallon or less at a time (say, primarily for hand-washing, and you only wash clothes or take baths once/week), your on-demand won't meet it's EF numbers, may even perform lower than a decent tank (but not likely.)

There's a ton of information (prolly more than you ever wanted to know :-) ) on the subject here:

http://www.energystarpartners.net/ia/Water_heaters/Documents/WHPAGette_Final.pdf

For the true tankless performance, take a look at Fig 5.1 (p. 48 of the .pdf, or 42 of the printed document). At 2 gallons/draw it's no better than a tank's EF performance, but it'll clean the tank's clock at anything over 5 gallons/draw.

Here is more succinct & graphical comparative test summary from PG & E than the WHPAGette_Final.pdf document that demonstrates just how much of a difference actual use patterns effect operating efficiency (and how truly sucky standard-efficiency tanks perform relative to their EF numbers at low & moderate levels of more realistic use than an EF test):

http://www.aceee.org/conf/08whforum/presentations/1a_davis.pdf

Even one of the CONDENSING tank systems (heater #4) couldn't muster 70% under moderate use(!), and in the mid 60s under low use. The only tankless that was tested was a condensing version (heater #6- they didn't specify whose that was), and it too suffered slightly under low use, but not nearly as severely as standard efficiency tanks or even the crummier condensing tank. The only one that beat all of it's standardized tests under all conditions was a (definitely not cheap!) stratified condensing tank (heater #5).

I kinda wish they'd tested at least on of the standard-efficiency tankless units in this comparison, but it is what it is. The low mass of a tankless keeps it from falling off a cliff the way tanks do under low use conditions, but the low-use profile they used has a larger fraction of the total test volume in draws under 2 gallons (where tankless performance gets killed)- I suspect a standard efficiency tankless would have a similar degradation to the condensing tankless- subtracting 5-8% from the condensing version's performance is probably reasonable, meaning that in heavy use it'll be in the low 80s, moderate use around 75-78%, and low use around 70%- still better than the low-tech tanks under their best-case heaviest use.

The tank heaters DO fall off an efficiency cliff! None of the non-condensing standard-efficiency tanks (heaters 1-3) tested actually met their EF numbers in moderate-use profile, although they beat their numbers in heavy use profiles. If you're an on-the-go 1-2 person family that often takes weekends away (or only bathes once/week) the tankless is a far superior option. But the stay at home family doing 2 loads of laundry every night after the kids go to bed will still see an efficiency gain with a tankless, just nothing like multiplier the on-the-go single/couple experiences.

So, it kinda depends- if you're on the go, living alone (or a water-sparing couple), often take weekends away etc, you'll likely meet or beat your tankless EF numbers by a few percent, but won't even come CLOSE to your tank's (lower) EF numbers. If you're a mostly stay at home family of 5 you'll likely meet or exceed the EF numbers for either, and the Consumer Reports analysis could be correct, but is it? No way to tell- the don't specify price & inflation assumptions. But check your actual fuel costs- they vary considerably with location. Here in MA we pay 2.5-3x the rate for natural gas as they do in UT.

For as-used efficiency comparisons, gas-fired tanks are all about maximizing the total consumed volume. If that's you/yours, great. But if its not, your actual efficiency isn't anywhere NEAR what the nameplate or EF number say. Getting efficiency out of a tankless is only about minimizing the number of very-low volume draws.

But the real reason to go tankless is to save your marriage- you never hear the screech from your spouse about the cold shower (did they factor in the cost of a divorce in the financial model for the tank? :-) )

In the Consumer Reports article they deftly dances around the longevity & service issues too- they didn't add in a full -replacement of the tank heater, simulate only an 11 year use (by excessively hardening the water- which is also a dubious method) yet say it "can take up to 22 years to break even—longer than the 20-year life of some model". In my accounting book I'd have to double the purchase & installation costs of the tank, yet apply only a 1.25 multiplier to the tankless. Tanks RARELY give 20+ years of best-efficiency service before out & out replacement replacement is required whereas tankless burners are easily serviceable (even heat-exchanger replacements), and the bulk of the "extra" installation costs are presumed electrictal outlets for the powered venting & controls and presumed gas line capacity upgrade. A full replacement of the tankless after 20-25 years of service won't be NEARLY the numbers quoted, since electrical power, gas lines & stainless flues etc. would already be in place- it'll be about the same as the tank. In many instances the gas lines might already be big enough to deliver, needing no upgrade.

It's true that while it's easier to service, the tankless will likely NEED to be serviced at least a couple of times in 20 years (I've got one that's 15 years old and going strong without any service beyond brushing out the heat exchanger once, but it's less complex than the Noritz & Takagis they tested). But then again, is swapping anodes every years and annually draining sludge from your tank really less work than swapping filters & occaisionally checking for lime scale on the tankless, cleaning as-necessary? It's a crap shoot, sez me, but in most situations the efficiency of the tankless will be better. Whether it ends up being totally dollars & cents cost effective is something you'd need to analyze, but I've yet to hear from anybody who went back to a tank after living with a tankless.

If you're considering it ever, PLEASE do a better job of the analysis than the Consumer Reports folks, eh? They adequately explain neither their test procedures nor their financial analysis, projected fuel prices, etc.. I found the article pathetically devoid of essential detail, and high on "we know better, and thus recommend..." attitude. (Can't say I'd recommend buying their mag, eh? But I s'pose I'm just coppin' an attitude myself. ;-) )

But...











...there's another FAR better option for many:

If your space heating system is done with a mid-efficiency (83%+) or higher hydronic (pumped hot-water) boiler, an indirect-fired HW heater running off the boiler will give you similar performance for less money, without the cold water sandwich. Done right, it should be capable of keeping up with continuous-demand of back-to-back showers (even with guests), just as a tankless would. And by increasing the duty-cycle of the boiler, it would improve the overall heating-system efficiency.

Standby losses of an indirect are far lower than that of a selfstanding gas fired tank, since the plumbing penetrations are small so it can be fully & insulated (the selfstanding has flue & burner penetrations & clearances to contend with) it doesn't have a flue to convect heat out of the tank 24/7, or a pilot light burning 24/7 (literally half the gas consumption of the heater for many 1-2 person families.)

Indirect fired tanks off the hydronic boiler is THE way to go whenever it's an option. Beyond that, you'll get better performance out of an on-demand. If the cold-water sandwich is too much of an annoyance, there are moderate-cost adder ways around that too:

http://www.tractorbynet.com/forums/attachments/related-topics/61100d1158263375-tankless-water-heater-code-question-cold_water_sandwich.pdf

[Dunbar Plumbing]

It's true that while it's easier to service, the tankless will likely NEED to be serviced at least a couple of times in 20 years




At least? Did you happen to forget that the mfg of just about all product require annual deliming/descaling of the compartment? Shorter timeframes if the water is really hard?


You're implying to put it in and forget it, just like tank water heaters. People treat their plumbing just like that, and they are surprised when I tell them the tank needed to be drained once a year.


With this being known, and a tankless in a "have to" situation in order to provide the hand crossing the flame speed in heat transfer,

you're sending an incorrect message to the majority to think that this product offers such reliability.

If it did, there wouldn't be so much discussion as to "should I" without considering the variables.

You seem knowledgeable about the product and quick to defend it. Are you in the United States,

and are you in a warm climate area where these devices can be mounted outside, or have a less than 40 temp rise to overcome.


Where's Master Plumber Mark and his tankless experiment on the gas savings we used to follow...

[nhmaster]

They are here. Poeple are buying them. I doubt like hell they are going to go away anytime soon but dollar for dollar they are a huge waste of money. Not worth the argument.

[chris8796]

Even one of the CONDENSING tank systems (heater #4) couldn't muster 70% under moderate use(!), and in the mid 60s under low use. The only tankless that was tested was a condensing version (heater #6- they didn't specify whose that was), and it too suffered slightly under low use, but not nearly as severely as standard efficiency tanks or even the crummier condensing tank. The only one that beat all of it's standardized tests under all conditions was a (definitely not cheap!) stratified condensing tank (heater #5).

I kinda wish they'd tested at least on of the standard-efficiency tankless units in this comparison, but it is what it is. The low mass of a tankless keeps it from falling off a cliff the way tanks do under low use conditions, but the low-use profile they used has a larger fraction of the total test volume in draws under 2 gallons (where tankless performance gets killed)- I suspect a standard efficiency tankless would have a similar degradation to the condensing tankless- subtracting 5-8% from the condensing version's performance is probably reasonable, meaning that in heavy use it'll be in the low 80s, moderate use around 75-78%, and low use around 70%- still better than the low-tech tanks under their best-case heaviest use.

The tank heaters DO fall off an efficiency cliff! None of the non-condensing standard-efficiency tanks (heaters 1-3) tested actually met their EF numbers in moderate-use profile, although they beat their numbers in heavy use profiles. If you're an on-the-go 1-2 person family that often takes weekends away (or only bathes once/week) the tankless is a far superior option.

If you follow the low use profile, 28 gal a day, that is 28g x 30 days x 8.8 lb/g x 50 F temp rise = 369600 btu/month.

At .70 EF standard tankless thats =528000 btu = 5.3 therms.
At .45 EF tank = 821333 btu =8.2 therms

Difference =8.2-5.3= 2.9 therms a month. I pay 95 cents a therm, so a savings of $2.75 cents a month. That tankless will pay for itself in no time.

[Ladiesman271]

and are you in a warm climate area where these devices can be mounted outside, or have a less than 40 temp rise to overcome.


Where's Master Plumber Mark and his tankless experiment on the gas savings we used to follow...


I have an older ELM Aquastar 125VP. Incoming water temperature is about 40 degrees, and that means a temperature rise of 80 to 90 degrees at this time of the year. The unit is rated for 2.09 gallons pe minute with a 90 degree rise.

The other day I measured the rate of water use that I used while taking a shower. The rate of water use during the shower was 1 gallon per minute and about 1/3 of that was from the cold water mix.

Unless you are taking 2 or 3 showers at the same time, a gas tankless works just fine even with cold water coming in!

[Ladiesman271]

If you follow the low use profile, 28 gal a day, that is 28g x 30 days x 8.8 lb/g x 50 F temp rise = 369600 btu/month.

At .70 EF standard tankless thats =528000 btu = 5.3 therms.
At .45 EF tank = 821333 btu =8.2 therms

Difference =8.2-5.3= 2.9 therms a month. I pay 95 cents a therm, so a savings of $2.75 cents a month. That tankless will pay for itself in no time.



More like a 90 degree temperature rise at this time of the year (in MA).

Your cost of gas is low. My per therm cost is $1.24240 per therm for cost of gas, plus $.54100 per therm for distribution charge for first 50 therms, and $.24660 for each therm over 50. Then there is the distribution adjustment charge of $.01128 per therm.

My gas total is a minimum of $1.50 per therm for the cost of gas during winter heating months, and and around $1.80 per therm during low use months.

[Dana]

If you follow the low use profile, 28 gal a day, that is 28g x 30 days x 8.8 lb/g x 50 F temp rise = 369600 btu/month.

At .70 EF standard tankless thats =528000 btu = 5.3 therms.
At .45 EF tank = 821333 btu =8.2 therms

Difference =8.2-5.3= 2.9 therms a month. I pay 95 cents a therm, so a savings of $2.75 cents a month That tankless will pay for itself in no time.

You currently pay a only bit more than half what folks in New England are paying for NG (59% of what I paid on my last bill in MA, and I'm in the cheap-zone of New England). If you anticipate only paying $0.95/therm from now until 2025 I suspect you're being a bit optimistic in your assumptions...

Using the EF numbers to calculate anything it a grotesque distortion. EF testing involves 6 equal draws of 10.7 gallons one hour apart which exactly how NOBODY uses water. The test is currently undergoing revision- expect a new, if not necessarily improved version by 2010. The testing by PG & E was part of an attempt to rationalize/harmonize the subsidy incentives based on EF numbers, etc. It basically proves that the EF test as currently implemented isn't up to task of determining true efficiency.

If the tank's effective efficiency is .45 for a 28gallon a day profile, that's true on average efficiency only if that much is used EVERY day. My "on the go many weekends away" intermittent singles/couples users will see much lower efficiency than even the 28 gallon daily use profile indicates unless they're religious about turning the HW tank off every time they head out for more than 24 hours. But their tankless efficiency will remain the same no matter how intermittent their use is.

[Edited to add] If the tank has a standing pilot it'll usually be burning somewhere between 5-10 therms/month. When the tank is actually in use, some of that heat goes toward temperature maintenance and not fully wasted. But for the "weekends away" intermittent user figure on at least 1/4 therm+ thrown away for every full day that you're off skiing, gambling, at the beach whatever. Depending on standby flue losses (bigger on atmospheric drafted tanks than forced draft versions) and how well insulated the tank is, that easily climbs to a half-therm/day and higher. The ~3 therms/month cited for the 28 gallon/day profile is underestimating it by at least half for the weekends-away crowd.[end edit]

The purely economic arguments for/against tankless have many assumptions (few of which were indicated in the Consumer Union report, which was also based on a testing profile MOST favorable for the tank.) Anyone doing it purely for economic reasons needs to do their own math, based on their own assumptions, use patters, fuel costs, and the CU report didn't provide even a hint of a framework from which readers could make an informed estimate. From a convenience & creature comfort "installation costs be damned" point of view, I've yet to encounter anybody who SO disliked the quirks of a tankless that they ever went back to a tank. (I'm sure there are some counterexamples to prove the rule, but they're rare.)

Another assumption often built into the arguments is that use profiles will remain constant independent of heater type. But the endless shower just isn't possible with a tank, and many end up using more HW when a tankless is installed. But due to the inherently higher efficiency that rarely results in an actual increases in fuel use.

I'm not a huge advocate of standalone tankless HW heaters on the economics alone, but I found the CU report to be SO sketchy and misinforming (based on what academic & utility company studies have shown, forget about the DOE's EF numbers) that I felt compelled to spell it out a bit better. I AM an advocate for low temp hydronic heating and indirect-fired tanks, where true gains in efficiency (measured as significant reductions in fuel use) can be made. In low heat load homes (most of the 2000' or smaller homes in the US would qualify), using a tankless as a low-mass modulating boiler in a combi HW system costs about the same as a cast iron boiler + indirect tank, but can be designed to run significantly more efficiently (with sub-140F water.) It won't be as efficient as a modulating/condensing boiler, but it won't cost as much either- it's a middle-ground approach. In practice it'll beat most single-stage condensing gas furnaces + gas-fired tank.

Variations on the the theme are currently being studied by utlities in California and Canada (eg, the eKoComfort comparison paper), and in the next couple of years there should be more published data on particular configurations. In eKoComfort combi comparison the unbuffered air-handler coil running off the tankless beat the tank combi system by about 10% in overall fuel use- about 1.5-2x what the raw combustion efficiency numbers might have indicated (and a heat/HW combi is by far a best-case absolute highest duty cycle use that a tank heater could achieve.) In a buffered tankless scenario, the tankless would cycle longer and far less often, reducing wear while improving net efficiency over coil-in-air-handler system.

Last but not least, presuming that a tank in an "install & forget" setup will be running anything like it's (already paltry) new-unit efficiency is another bad assumption too. Annual or seasonal purging of the sludge settled in the bottom is required to keep the heat exchange coefficient from suffering, as well as swapping out sacraficial anodes every few years. Hard water de-scaling is usually only a problem requiring anual maintenance for tankless systems in areas with actual high hardness. Most municipal systems are chemically buffered sufficiently that it can be put off for 3-5 years, or until there's a noticable drop in output. (I've seen one tankless system that went 15 years without de-scaling or any service whatsoever, and it's still in service. I've yet to see a neglected tank last that long, but I'm sure there are a few around.) All gas burners need maintenance.

[chris8796]

The other day I measured the rate of water use that I used while taking a shower. The rate of water use during the shower was 1 gallon per minute and about 1/3 of that was from the cold water mix.

Unless you are taking 2 or 3 showers at the same time, a gas tankless works just fine even with cold water coming in!

A gallon a minute is admirable, 90+% of the population would not want a shower at 1 g/min. Most people demand 2 g/min shower and shower heads are mandated to be 2.5 g/min.


More like a 90 degree temperature rise at this time of the year (in MA).

The calculation was an average, my annual average cold water temp is 55 (today it is probably 40!, upper midwest). The average shower temp is 105, hence a 50 degree rise.


Your cost of gas is low. My per therm cost is $1.24240 per therm for cost of gas, plus $.54100 per therm for distribution charge for first 50 therms, and $.24660 for each therm over 50. Then there is the distribution adjustment charge of $.01128 per therm.

My gas company charge a flat customer fee and a meter fee with a PGA charge and dist fee. The pga and dist fee equals 95 cents a therm. My gross costs are higher if you incorporate the fixed fees, but don't apply in this comparison.

I'm not anti-tankless, everyone needs to crunch their own numbers. I'd have one if I had a big whirlpool tube I needed to fill. I don't think one size/type fits all works for WH. Tankless are great in the southwest, where they are mounted outside and have warmer water temps. AC heat recovery is great for south florida. A boiler system is great for the Northeast. Tank units may be best in the midwest. Electric units may be better if you only other options is propane. Drain heat recovery may be viable depending on you use profile. Solar can be an option for some. Heat pump recovery, etc. I'm just skeptical when anyone only recommends one solution and don't now the particulars for a specific case.

At the end of the day, everyone needs to do their own research and find the solution that best fits their needs. If your dependent on plumbers for your plumbing needs, your local plumbers will greatly impact the economics of your decision.

[gregsauls]

Crunching number does not apply when considering what my needs were for a household of 6. Tankless WH provided the needs for our family.

[Dunbar Plumbing]

If your dependent on plumbers for your plumbing needs, your local plumbers will greatly impact the economics of your decision.




The majority, and people who buy these units?

Never drained their water heater once a year.


Explain how the thinking will now change on these matters.



I defend my own statements because I have hands on plumbing products every day, and people do not understand that these devices are not a put-it-in-and-forget-it mentality.


That's why I come to the plate on these discussions because the "average" homeowner, the "majority" that use nearly "all" plumbing systems are not going to have the insight like a select few of you crunching therms and showing $2.75 savings like it was a free 2 liter of pop at the local convenient store.


The reality is maintenance is the key to run these devices, when they malfunction like they will, they are expensive and the average customer isn't going to understand "clean flow switch screen" or know how to troubleshoot a code error on the digital touchscreen on the unit.


You can information overload the internet with tankless treats, but the average consumer is forced to call a plumber OR tech support to get their hot water back.


The basic of idea of creating hot water just got more difficult, not simpler. That's not to say that tankless won't have its place in America, it will.

Anyone who buys one of these is a daredevil right now since the odds are against them that their neighbor has one, and someone knowledgeable is right there to fix them when they break, immediately...


not hours I'm speaking of, days. Do you know what it is like to be without hot water for days?


What happens if a certain "part" costs more than a tank heater to replace? Now you're faced with a device that in average thinking, a tank heater for less as a whole looks pretty darn inviting from that aspect of keeping money in your pocket.

Isn't that what this product is all about, keeping money in your pocket?


IF you pay a plumber annually to correctly delime/descale these units according to mfg. specs, call on them to fix every malfunction these units have over the course of time, there are no numbers you'll ever produce that states in legitmacy that the cost outweighs the performance value. Never.

Anything mechanical can and will fail. A retrofit to a newer model won't allow a reconnect to the existing stainless steel flue, it will void the warranty even though it is the same damn thing.


These are all "charges" that get way-layed into the customers back pocket, all the while the plumber is making a mint on the green idea.


Why is it that a tank water heater after initial heat up can maintain ready to use hot water for days, on just a standing pilot alone? Or are you going to tell me that the cost of that flickering match flame is ungodly expensive and horrible in gas consumption.


There's lots of observants that follow my thinking when I type on the internet about these products. They might not ever put their voice to print, but I think they understand that I'm pointing out some very credible points of interest in the concern of going after new ideas that can have one simple common issue, cost.

So as a troubleshooter as a service plumber constantly working on products such as these, understanding the ins and outs of how things work,

You provide the positives and I'll provide the actuals. I think that's a fair and balanced approach to any time someone cheerleads something that in actual time span is going to have to realize that there's hidden costs to when plumbing attacks.

[Ladiesman271]

A gallon a minute is admirable, 90+% of the population would not want a shower at 1 g/min. Most people demand 2 g/min shower and shower heads are mandated to be 2.5 g/min.




What percent of the population has ever measured the amount of water used per minute for their showers? That would be just about 0% if you ask me. The other day I measured my flow rate for the first time ever. 1 gallon per minute works just fine.

The mandate for shower heads is 2.5 gal/min MAXIMUM. You are allowed to use less than that flow rate. Also, 100% of the water used is not hot water. You should measure the actual amount of water that you use in shower before you throw out numbers!






The calculation was an average, my annual average cold water temp is 55 (today it is probably 40!, upper midwest). The average shower temp is 105, hence a 50 degree rise.





The average shower temperature does not mean anything. Water has to be heated to well over 105 degrees to fill a tub with 105 degree water in the tub. When you take a shower, you mix hot and cold water together to get 105 degrees. Your calculated temperature rise is low, and your hot water volume used per minute is high.

[chris8796]

Dana,

Oddly, I don't think we are too different in our opinions. We both appreciate either side can easily manipulate the numbers to justifiy their case.

I like the idea of a better "overall" solution. The combi approach is interesting. I would like to see more solar thermal applications and I can see how you could intergrate with this approach. I think a major stumbling block with solar WH is the cost to garuantee constant hot water. A solar water heater could provide 90% of your HW needs but that last 10% will cost you. Either in capital (Tankless) or standy loses with a tank heater. If you could have a combi system that could easily incorporate thermal solar plus with some heat storage options, it becomes attractive in overall energy use.

[chris8796]

What percent of the population has ever measured the amount of water used per minute for their showers? That would be just about 0% if you ask me. The other day I measured my flow rate for the first time ever. 1 gallon per minute works just fine..

They don't have to measure it to know it is too weak for thier liking. I have taken a 1 gal/min shower (thanks to galvanized plumbing) and know it is weak. It may be normal for you, but the vast majority of Americans would be disaapointed with 1 g/min


The mandate for shower heads is 2.5 gal/min MAXIMUM. You are allowed to use less than that flow rate. Also, 100% of the water used is not hot water. You should measure the actual amount of water that you use in shower before you throw out numbers!

I have measured mine, 2.2 g/min, not bad-not great as showers go. I've measured the hot water temp, the cold water temp, the drain temp and the drain temp after the drain water heat exchanger. So I'm not a novice on the topic.



The average shower temperature does not mean anything. Water has to be heated to well over 105 degrees to fill a tub with 105 degree water in the tub. When you take a shower, you mix hot and cold water together to get 105 degrees. Your calculated temperature rise is low, and your hot water volume used per minute is high.

The energy use is the same for calculation purposes. 50 gallons at 100 F requires the same energy whether you heat 50 gallons from 50 F to 100 F or you mix 25 g of 150 F water (orig 50 F) with 25 g of 50 F water. The specific heat of water is fairly constant over this temperature range.

[jadnashua]

My winter cold water supply can and has approached 33 degrees. The most temp rise most of the tankless can provide is maybe 90-degrees. Considering it has to run through nearly 40' of pipe to get to my shower, even at all hot, there may not be enough hot for a comfortable shower - it does cool off along the way regardless of the insulation. It all depends on where you live, and your expectations. Some of the tankless restrict the flow to maintain the temp rise, some don't, and the output just gets colder making getting just the right temp nearly impossible to attain.

I'm glad I switched to an indirect...obviously, that's not an ecconomical option unless you have a boiler, but I do, and did...much better!

[Ladiesman271]

They don't have to measure it to know it is too weak for thier liking. I have taken a 1 gal/min shower (thanks to galvanized plumbing) and know it is weak. It may be normal for you, but the vast majority of Americans would be disaapointed with 1 g/min




That is meaningless. There are shower heads, and there are shower heads. The type of shower head makes a huge difference on what the water flow feels like when it is compared with the maximum flow rate.


http://www.jet-streamshowerhead.net/work.html


Around here, the state water authority went around and changed everyones shower heads to a low flow air mix type of shower head. Mix some air in with the water, and the spray feels nice and strong. I have never measured the maximum flow rate.







I have measured mine, 2.2 g/min, not bad-not great as showers go. I've measured the hot water temp, the cold water temp, the drain temp and the drain temp after the drain water heat exchanger. So I'm not a novice on the topic.




There are full flow shower valves and adjustable flow shower valves. If you can't adjust the flow for comfort, then the shower head determines the flow rate. I can adjust my flow rate for comfort, then I measured the result.








The energy use is the same for calculation purposes. 50 gallons at 100 F requires the same energy whether you heat 50 gallons from 50 F to 100 F or you mix 25 g of 150 F water (orig 50 F) with 25 g of 50 F water. The specific heat of water is fairly constant over this temperature range.




The point was you can run out of temperature rise with a tankless to make those calculations useless!

[Scuba_Dave]

That is meaningless. There are shower heads, and there are shower heads. The type of shower head makes a huge difference on what the water flow feels like when it is compared with the maximum flow rate.

http://www.jet-streamshowerhead.net/work.html

Around here, the state water authority went around and changed everyones shower heads to a low flow air mix type of shower head. Mix some air in with the water, and the spray feels nice and strong. I have never measured the maximum flow rate.

There are full flow shower valves and adjustable flow shower valves. If you can't adjust the flow for comfort, then the shower head determines the flow rate. I can adjust my flow rate for comfort, then I measured the result.

Where is "around here" ? I'd be interested to know what State authority - US/UK other ? Frankly if I liked the shower head I'd keep it. If I didn't I'd yank it out

We had a 30g oil fired that went & we switched to a 50g high efficiency electric - no gas to the house. We need a new boiler so I want a hot water coil i n the boiler. In the winter the boiler will run & take the load off the electric. In the warmer weather a solar heater will assist. We have about 80 psi here, pretty good flow.
Between these 2 methods I'm hoping to cut the electric use

It's 12 degrees out & my input Temp is around 46-48. The basement has dipped to 54 from normal temp of 58-63. The next fgew days will be even colder
I'm not sure what the gpm is, but I've been in lower psi areas & the flow for taking a shower is poor. Some of this may have to do with the design of the shower head

[Ladiesman271]

My winter cold water supply can and has approached 33 degrees. The most temp rise most of the tankless can provide is maybe 90-degrees.




Maximum temperature rise depends on the flow rate required.






Considering it has to run through nearly 40' of pipe to get to my shower, even at all hot, there may not be enough hot for a comfortable shower - it does cool off along the way regardless of the insulation. It all depends on where you live, and your expectations. Some of the tankless restrict the flow to maintain the temp rise, some don't, and the output just gets colder making getting just the right temp nearly impossible to attain.




My longest run is about 60 feet and is insulated. I set the heaters thermostat for about 125 degrees measured at the kitchen sink. I have never had a cold shower. I always have to mix in cold water for a comfortable shower.

To maintain the water temperature my particular heater uses a modulating gas burner (25K to 125K BTU) which is controlled by a thermostat that measures the outgoing water temperature. It has a fixed flow restrictor that limits flow to a maximum of 3 1/4 gallons per minute. Not sure of the maximum rise that I can out of the unit, but it is around 85 degrees right now (40 degrees input - 125 degrees output).

[Ladiesman271]

Where is "around here" ? I'd be interested to know what State authority - US/UK other ? Frankly if I liked the shower head I'd keep it. If I didn't I'd yank it out

We had a 30g oil fired that went & we switched to a 50g high efficiency electric - no gas to the house. We need a new boiler so I want a hot water coil i n the boiler. In the winter the boiler will run & take the load off the electric. In the warmer weather a solar heater will assist. We have about 80 psi here, pretty good flow.
Between these 2 methods I'm hoping to cut the electric use

It's 12 degrees out & my input Temp is around 46-48. The basement has dipped to 54 from normal temp of 58-63. The next fgew days will be even colder
I'm not sure what the gpm is, but I've been in lower psi areas & the flow for taking a shower is poor. Some of this may have to do with the design of the shower head



http://www.mwra.com/04water/html/watsense.htm


I just noticed that the MWRA web site has a link to the toilet section of the Terry Love web site.

http://www.mwra.com/comsupport/watersaving/toilets.htm

[Scuba_Dave]

http://www.mwra.com/04water/html/watsense.htm

Ah - so in MA too, we aren't in the MWRA area
From what you said I thought it was a mandatory replacement program. It would be nice of there was a "loaner" shower head program. Take a low flow shower head home (with deposit) & try it out, if you like it keep it - if not return it

There are still a lot of high gallon toilets out there

[Ladiesman271]

Ah - so in MA too, we aren't in the MWRA area
From what you said I thought it was a mandatory replacement program. It would be nice of there was a "loaner" shower head program. Take a low flow shower head home (with deposit) & try it out, if you like it keep it - if not return it

There are still a lot of high gallon toilets out there


It was "mandatory" to a large extent. Over ten years ago they had crews go around town and provided and installed everything at no charge. I still have all of my 50 year old toilets. The MWRA installed water dams in each one of them. The shower heads are rated at 2.2 gpm or lower. They are the air mix type, so the force of the water feels higher than a standard flow unit


Seems like the water consevation programs have helped out with water use.

"Operation WaterSense, a joint program of MWRA and its communities, offers conservation services directly to MWRA communities. The program has helped reduce demand from 330 million gallons of water per day to 220 million gallons of water per day, and has helped residents control their water, sewer and energy costs."

[Dana]

Dana,

Oddly, I don't think we are too different in our opinions. We both appreciate either side can easily manipulate the numbers to justifiy their case.

I like the idea of a better "overall" solution. The combi approach is interesting. I would like to see more solar thermal applications and I can see how you could intergrate with this approach. I think a major stumbling block with solar WH is the cost to garuantee constant hot water. A solar water heater could provide 90% of your HW needs but that last 10% will cost you. Either in capital (Tankless) or standy loses with a tank heater. If you could have a combi system that could easily incorporate thermal solar plus with some heat storage options, it becomes attractive in overall energy use.

I don't think it's odd at all- we both can do the math (and probably the plumbing too. :-) ) I found the CU article slanted, condescending, and unenlightening, with no framework around which people could do their own cost/benefit analyses. It was a dis-service their readership. For the strictly HW use, it all depends on how you use hot water, and what your fuel costs are (which vary by more than a factor of 2 on both axis'), and not at all addressed by the CU article.

Many if not most newer solar heated homes are using tankless HW heaters as backup and "finish" heat for lukewarm storage, and in that application it's the right way to go. Also, more and more people are moving toward low-temperature hydronic heating in their freshly insulaton-upgraded & air infiltration upgraded homes too. When a tankless modulating HW heater's burner exceeds the house's design-day heating load by a factor of 3 or 4, using an oversized cast-iron boiler just to be able to run an indirect-fired tank isn't very efficient (still probably better than a tank HW heater + a right-sized cast iron boiler though). Utilizing a modulating mid-efficiency burner like a tankless as the combined system's heat source then becomes more cost effective up front, and significantly more efficient. With a tankless the modulation factor "right sizes" it semi-automatically to match the actual instantaneous heat load, whether the instant demand is for hot water or to run a hydronic heating zone.

Using a low-head reverse-indirect HW heater as both the space heating buffer and the hot water heater makes for a very nice space-efficient package too. With a single buffer that all heating zones draw from/return to in place, once properly adjusted, the delta-T that the burner needs to support varies with the volume & temperature of the return water from the zones. The flame modulates up & down as the zone demands kick on & off, and only when all zones turn off and the high-limit aquastat on the buffer tank trips does the tankless flame turn completely off. This is a tried & true system architecture adapted from large building heating plants, but applied in micro-scale to micro-zoned residential structures. Actual fuel savings are usually well into double-digit percentages with this approach compared to bang-bang on/off controls.

BTW: Many manufacturers void the warranty for tankless HW heaters used as boilers in heating systems, but I'm not sure why this should be so. If the system has even 10-15 gallons of buffering capacity the number & depth of thermal cycling will go down relative to HW use only. Takagi seems to be the only manufacturer actively encouraging combi or space heating use across their entire product line, but there are many many Rinnais and others running (off warranty) heating systems. A relative newcomer to the US market, Navien has pre-engineered some heat-exchangers & controls to make (un-bufrered) combi-system design easier: http://www.heatingbox.com/

Navien condensing units seem to have a following among the solar-heating combi-crowd, but take "condensing" with a grain of salt here, eh? (I haven't seen any test data, but the "98% efficiency" number they tout is likely only going to hold true when the water entering the heater is well under 50F, whereas in most heating applications return water much under 100F isn't the norm. It might hit 88-89% combustion efficiency in a heating application though- better than the ~85% combustion-efficiency of a standard tankless running ~100F return water (the eKoComfort measurements). I'm not sure the condensing unit it's worth the extra money though- the difference price could buy you another 40 square feet of installed flat panel, with a bigger reduction in annual fuel use in much of the lower 48. (I'd leave that up to the local solar designer to do the math on, but it's worth asking the question at design-review time.)

As houses become tighter & better insulated to the point where instanteous heat load far outstrips HW heater output capacity, a wave of combi systems (includting tankless HW heater types) is coming. Time will tell where the costs & benefits break down, but it's getting harder & harder to rationalize clunky oversized cast-iron boilers as fuel prices rise when low-mass modulating systems are available, and more efficient. My design-day heat load is about 30kbtu/hour, in an area with about a ~6800 degree-day climate. I could clearly run both heat & HW combi off a 199kbtu/hour in (~165kbtu out) tankless with margin to spare, getting far more use & value out of it than if used merely as a HW heater. For that matter, I could heat both my house & HW with most 50gallon gas tank heaters too (I've considered it, calculated it, modeled it, since the up front cost is SO cheap, but...), with a 10-15% comparative performance hit. YMMD.

[Redwood]

Given some of the threads here outlining problems with Takagi units and getting the problem fixed I'll pass on the Korean Takagi...

I'm in the Northeast with some pretty cool water temps about now. I will state IMHO that the only payoff I see in tankless is with gas fired units for a situation where the home owner want an unlimited amount of hot water within the flow rate allowed by the heater(s) installed. I.E Large family with back to back to back showers and baths, larger tubs, & carwash showers. Show me otherwise and somebody is cooking the books!:cool:

[Dana]

Given some of the threads here outlining problems with Takagi units and getting the problem fixed I'll pass on the Korean Takagi...

I'm in the Northeast with some pretty cool water temps about now. I will state IMHO that the only payoff I see in tankless is with gas fired units for a situation where the home owner want an unlimited amount of hot water within the flow rate allowed by the heater(s) installed. I.E Large family with back to back to back showers and baths, larger tubs, & carwash showers. Show me otherwise and somebody is cooking the books!:cool:


:-) :-) :-) :-) :-) :-)

Yabbut, you don't get it, they're not Takagis they're Naviens- Naviens go to eleven, Takagis only go to 10... ;-) (Some Noritz models are Takagis- barely more than a nameplate change. Ever wonder why some Noritz models use Takagi remote controls? )

But in fact Naviens are their own design, probably come with their own unique sets of misery! ;-)

The scuttlebutt that some of the design team came from Takagi doesn't say much either way about 'em. They coulda been the guys who specified or designed the less-than-fully-reliable flame detector for the TK2, but they just as easily have been the guys who wanted to do it right, but were overridden by the group consensus or management, and thus were happy to bolt to a more receptive Navien when the opportunity presented itself. (I've seen many variations on this movie.) Chryslers didn't become Fords when Iacocca bolted either.

Whether the Navien proves more reliable than the competition remains to be seen, but local technical support and parts availability are useful for any device this complex. Tanks are definitely simpler beasts, with more limited sets of problems (but I've seen issues with electronic ignition on tanks less than 2 years old too, eh?) The complexity buys you some efficiency, but only at some cost. It's not a "set and forget" world, and is becoming less so every day. Where the cost/benefit is for anybody has a lot of factors (damned few of which were addressed in the CU article.)

[nhmaster]

When will this topic just DIE. :eek:

I will sum up tankless water heaters;

Expensive to buy
Expensive to have installed
Somewhat less expensive to operate
May not produce enough hot water
Work better in warmer climates
Work better with good water conditions
May not meet code in all localaties (remember the code does say that you have to provide hot water to all fixtures in the home)
Require regular service
Cause heated arguments that never ever seem to end.

[Dunbar Plumbing]

:-) :-) :-) :-) :-) :-)

Yabbut, you don't get it, they're not Takagis they're Naviens- Naviens go to eleven, Takagis only go to 10... ;-) (Some Noritz models are Takagis- barely more than a nameplate change. Ever wonder why some Noritz models use Takagi remote controls? )

But in fact Naviens are their own design, probably come with their own unique sets of misery! ;-)

The scuttlebutt that some of the design team came from Takagi doesn't say much either way about 'em. They coulda been the guys who specified or designed the less-than-fully-reliable flame detector for the TK2, but they just as easily have been the guys who wanted to do it right, but were overridden by the group consensus or management, and thus were happy to bolt to a more receptive Navien when the opportunity presented itself. (I've seen many variations on this movie.) Chryslers didn't become Fords when Iacocca bolted either.

Whether the Navien proves more reliable than the competition remains to be seen, but local technical support and parts availability are useful for any device this complex. Tanks are definitely simpler beasts, with more limited sets of problems (but I've seen issues with electronic ignition on tanks less than 2 years old too, eh?) The complexity buys you some efficiency, but only at some cost. It's not a "set and forget" world, and is becoming less so every day. Where the cost/benefit is for anybody has a lot of factors (damned few of which were addressed in the CU article.)




Just drop the damn link and get it over with. Sheesh! :mad:

[Redwood]

Just drop the damn link and get it over with. Sheesh! :mad:

I'm with you Rugged.:mad:

Here I'll put the damn link up! Maybe he'll go away then!
http://www.navienamerica.com/products/condensing-residential.html

I'll let someone else be the guinea pig!
When I hear nothing but good news I'll jump on the band wagon....
I'll breath until then thanks.

[Ladiesman271]

This morning I measured the flow rate of my shower head with the flow rate set to full on. My shower head is indeed a 2.2 gallon per minute shower head. I just set the volume knog in the shower to the flow rate that feels comfortable. That comfortable flow rate is about 1 gpm,and about 1/3 of the water is from the cold valve.

I would not be surprised if I could run two simultaneous showers even with the current low 40 degree incoming water temperature. I will test that after I get my second shower finished up.

Obviously, some people do not like "low flow" shower heads. They require something more like the Commando 450!


http://www.youtube.com/watch?v=dlrtQb24Qxw&feature=related



http://www.youtube.com/watch?v=dlrtQb24Qxw

The IPC commisioned a study about the flow rate required to take a shower. They found it hard to complete the study.

http://www.youtube.com/watch?v=hUoyb1bgSAo&feature=related


http://www.youtube.com/watch?v=hUoyb1bgSAo

[nhmaster]

Die Die Die Please God just Die!:D

[WV Hillbilly]

Exactly what I've been thinking about the whirlpool water heater thread !!!!!!!!!!!!!!

[C NUMB]

When will this topic just DIE. :eek:

I will sum up tankless water heaters;

Expensive to buy
Expensive to have installed
Somewhat less expensive to operate
May not produce enough hot water
Work better in warmer climates
Work better with good water conditions
May not meet code in all localaties (remember the code does say that you have to provide hot water to all fixtures in the home)
Require regular service
Cause heated arguments that never ever seem to end.



I agree with the above quote with the exception of them working better in a warmer climate- No they don't!!

[99k]

Ok I waiting for my electric water to die and it won't ... so I'm going to bring it behind the barn and shoot it. We have a 45 yr/old furnace so I don't feel like creating hot water from the furnace. I am convinced I do not want a tankless. What about the stand alone gas heaters with a power ventilator? We don't have gas so I'd have to get a 100 gallon tank of propane. Does this option make sense and if so can you recommend a good brand. Thanks.

[nhmaster]

I agree with the above quote with the exception of them working better in a warmer climate- No they don't!!



Love you man. :D

[SewerRatz]

I agree with the above quote with the exception of them working better in a warmer climate- No they don't!!

Oh you can make them work great, if you put in more than one.

[gregsauls]

When will this topic just DIE. :eek:

I will sum up tankless water heaters;

Expensive to buy
Expensive to have installed
Somewhat less expensive to operate
May not produce enough hot water
Work better in warmer climates
Work better with good water conditions
May not meet code in all localaties (remember the code does say that you have to provide hot water to all fixtures in the home)
Require regular service
Cause heated arguments that never ever seem to end.

#1 Bought my Rinnai r74lsi for $675 +$150 for vent pipe. Subtract $300 fed tax rebate.

#2 Installed myself.... I can do good DIY !

#3 Yep, didn't really care about cost SAVINGS but did get some.

#4 FALSE, damn lies too! All the hot water I want for a family of 6...Fact!

#5 Live in NE Texas, good inlet water temps. I don't live north of MD line and life is good.

#6 No code issue, Gas company rep was drooling over it!

#7 Once a year. Own a vehicle and don't do routine service???

#8 Only by a few.... "up north folks"

Alternate hot water sources are here to stay. Being "green and energy efficient" will probably be mandated by the cmty for "change" that was just elected, like it or not.

[C NUMB]

gregsauls, you got a deal on that unit, around here they start at 1100. By the time you are done it is usually around $1600 installed with permit as long as you already have gas, if not it is closer to $2400.


BTW, I looked at your install on your blog, nice job!

[nhmaster]

Hooray!

I'm wrong yet again. (whips self while hanging head in shame):D

[gregsauls]

gregsauls, you got a deal on that unit, around here they start at 1100. By the time you are done it is usually around $1600 installed with permit as long as you already have gas, if not it is closer to $2400.


BTW, I looked at your install on your blog, nice job!

Thanks for the compliments! I did get a good deal from a local wholesale house a buddy of mine manages. Funny thing, "the bay of E" sellers were within a few $$ of the local price but having the backing of my buddy was worth it.

It's not a question of being right or wrong on going tankless. What needs to happen is for some to realize that what works for some may not work for others and more importantly... vice-versa. Tankless isn't the answer for everyone situation or location, but the fact remains it DOES work... at least for some.

So generic answers of "they suck" are highly biased and should be judged as such.

[Dunbar Plumbing]

gregsauls,



You're the minority. The less than 1% that can do these required tasks like installing it, maintaining it.


I talk for the 99% that don't, or CAN'T.


And what happens when your house of 6 loses hot water because of a malfunction...???



We already know; you're going to be the one on the phone to the 1-800 number, the rep who sold it to you, begging for overnight or same day air-shipment of parts that you "think" match the error code on the majic box on the wall.


6 people without hot water for hours, days isn't what I want. The majority want hot water within hours of a call to a plumber, to have the right parts and not fetch them from across the globe.


And what happens if you become disabled to work on that unit:


You just forced your family to really pay out the nose for repairs, maintenance, upkeep. You won't live forever, that's a known fact.


20 years from now when it's as common as a part at the local hardware store, yes. But right now it's a high risk for many, especially that buy the BS about the green way of life because point of use is a new word?


Point of use has been around for a long time, it just got elevated to handle a whole house. Nobody discusses the excessive use of these since they can take a 30-400 minute shower. Let's not talk about that, those car wash showerheads and what not.

EXCESS WITH AN EXCUSE. :cool:

[nhmaster]

I just can't resist... They Suck

forgive me lord..
That weren't funny :D

[gregsauls]

gregsauls,



You're the minority. The less than 1% that can do these required tasks like installing it, maintaining it.


I talk for the 99% that don't, or CAN'T.



EXCESS WITH AN EXCUSE. :cool:

I like being that special 1% "that can" !!!! Thank you for the compliment, seriously. I do not feel I put my family at "risk" installing a tankless in the least little bit. And quit honestly a scare tactic like that will keep people away from technology. If it fails, yes I will be on the phone for parts. Just the same way I would be at the big orange box store replacing a TANK water heater when it springs a leak.... lets only hope I am THERE when it does it and can do damage control.

All dogs have fleas.... but it's still my dog to love!

[Dunbar Plumbing]

I like being that special 1% "that can" !!!! Thank you for the compliment, seriously. I do not feel I put my family at "risk" installing a tankless in the least little bit. And quit honestly a scare tactic like that will keep people away from technology. If it fails, yes I will be on the phone for parts. Just the same way I would be at the big orange box store replacing a TANK water heater when it springs a leak.... lets only hope I am THERE when it does it and can do damage control.

All dogs have fleas.... but it's still my dog to love!



Good points taken, and yes, you should be proud that you can do this work yourself.


I was just mentioning the time factor from malfunction-to-repair that has people without water for days with a tankless.


That's why I mentioned that in 20 years that this problem will most likely be removed.

It has to get down to availability, common product to be worthwhile, which takes time.

As a plumber I can see myself getting hustled on these when they fail, when it comes to replacement.


Customer will take the old one off, put the new one on the wall and my job will be the "hook up" part and they'll minimize the effort stating, "Well I already mounted the unit for ya, sheesh! :rolleyes:"

Oh yeah, I can get that done for ya, $40 and a gallon of milk please.

[CarlH]

In my effort to help keep beating this dead horse, here is a chart comparing different types of water heaters and estimate costs.
http://www.aceee.org/consumerguide/waterheating.htm#lcc

Do the installed costs line up?

[nhmaster]

In my effort to help keep beating this dead horse, here is a chart comparing different types of water heaters and estimate costs.
http://www.aceee.org/consumerguide/waterheating.htm#lcc

Do the installed costs line up?


Oh that's beautifull Carl. Thank you. Though I have a feeling you are preaching to the choir. So about 30 bucks a year savings over a conventional tank heater. Sounds about right to me.

[gregsauls]

In my effort to help keep beating this dead horse, here is a chart comparing different types of water heaters and estimate costs.
http://www.aceee.org/consumerguide/waterheating.htm#lcc

Do the installed costs line up?

Good press numbers! Some will disagree with install figures. Your price may vary by region and plumber comfort with new technology.

[CarlH]

I've done some reading and my guess is that the installed cost is for new construction. Changing out a tank heater for a tankless can get much more costly for some. I was looking at the Rinnai tankless to see what it needs for an install. The fact that it is a direct vent is problem for me since it cannot use my existing flue and I cannot change out my existing flue since it is used by my furnace. This means that I would have to find a way add a new vent for this heater. This is where it gets ugly and would probably get expensive. The desired location of the heater puts it in a location where there are too many other things in the way to install a vent for the tankless. If I go with a different manufacturer that has a b-vent tankless, I run into a different problem. My current vent is inadequate and probably half the size that is required to run my furnace and a tankless. Then the question is whether or not I have room in the existing cavities for a larger vent. Also, a b-vent tankless is less efficient at a .70 EF.

I've been keeping my eye on the comments regarding tankless heaters and until now did not look too deep into what it would take for me to convert to a tankless. I now think that a tankless would not be a good fit for me. I should also add that my water is moderately hard at 130ppm and scale build up might be a problem for me that would require more frequent cleaning than once a year.

I'm all for being green, especially when it helps keep the green in my wallet. Converting to a tankless would not be cost effective for me though.

[Ladiesman271]

In my effort to help keep beating this dead horse, here is a chart comparing different types of water heaters and estimate costs.
http://www.aceee.org/consumerguide/waterheating.htm#lcc

Do the installed costs line up?



You have to install a new vent if you go with what they recommend for a tank type of water heater. Same type of vent problem as the tankless heaters.

---------------

Storage Water Heaters

These are by far the most common type of water heater in the U.S. today. Ranging in size from 20 to 80 gallons (or larger) and fueled by electricity, natural gas, propane, or oil, storage water heaters transfer heat from a burner or coil to water in an insulated tank. Because heat is lost through the flue (except in electric models) and through the walls of the storage tank, energy is consumed even when no hot water is being used.

New energy-efficient gas-fired storage water heaters are a good, cost-effective replacement option for your current water heater if you have a gas line in your house. They have higher levels of insulation around the tank and one-way valves where pipes connect to the tank, substantially reducing standby heat loss. Keep an eye out for the price to come down for newer super-efficient "condensing" and "near-condensing" gas water heaters, which save much more energy compared to traditional models but are currently niche products. For safety as well as energy efficiency, fuel-burning water heaters should be installed with sealed combustion ("direct-vented" or "power-vented). Sealed combustion means that outside air is brought in directly to the water heater and exhaust gases are vented directly outside, keeping combustion totally separate from the house air.

[Ladiesman271]

Oh that's beautifull Carl. Thank you. Though I have a feeling you are preaching to the choir. So about 30 bucks a year savings over a conventional tank heater. Sounds about right to me.



Good all around summary of various water heating methods. Note that they did not consider actual lifespan in their calculations.


--------------------


4. Currently, there is too little data to accurately estimate life expectancy for tankless water heaters, but priliminary data shows that tankless water heaters could last up to 20 years. For all water heaters, life expectancy will depend on local variables suck as water chemistry and homeowner maintenance.

[CarlH]

You have to install a new vent if you go with what they recommend for a tank type of water heater. Same type of vent problem as the tankless heaters.


Correct. No power vent, direct vent, or condensing water heaters for me. I'm looking at a conventional gas storage with a .62 EF. My current water heater rated at .55 EF and has given me nearly 15 years of trouble free service, including extended power outages.

I think it would be great if a tankless were a more viable option, but it is not an economical option for me. It would have been nice to get a bit more space and lower gas bills.

[nhmaster]

I don't see anything in the newer models to suggest that they will last any longer than the Aquastar and Paloma Pak units. Most of them made it around 10 years.

[Dana]

I don't see anything in the newer models to suggest that they will last any longer than the Aquastar and Paloma Pak units. Most of them made it around 10 years.

And you determined that by...










... market survey???

I know of two E.L.M. Aquastar (pre-Bosch takeover) that are still in service with 15+ years on 'em. Don't know of any that out & out died or needed a heat exchanger swap, but it's a pretty small sample size (and only one can I claim the installation on.) They're somewhat finicky PITA units with mechanical feedback that doesn't really modulate well, with a propensity for overheating then self-extinguishing at low flow, but they just won't die (as much as the current owner of one wishes it would. :-) ) I think of them as "reliably finicky". :-) Maybe I live/work in an area with fewer water-harness issues or something(?).

But the newer versions have both much higher efficiency and higher complexity. Their true track record is still being made, but the Rinnais & Takagis I've encounterd over the past 5 years all seem to be in good shape and running without problems. (I understand that some people have run into issues with Takagi flame-detectors, but I've yet to see it in person- perhaps I will some day...) Again- a relatively small sample-size.

I've yet to encounter anybody who replaced their tankless with a tank (except a few of instances where they were upgrading heating system boilers and went with an indirect-fired tank, which is the best of both worlds IMHO.) Have you?

I've read of people who had been using them as hydronic boilers trading up for mod-cons though.

They may not be for everyone, may not be cost-effective in low-cost fuel markets, but people don't seem to trade 'em in, and live with 'em despite their quirks. Hard-core greenies seem enamored of the operational efficiency, but that wouldn't describe the average tankless owner in my neck of the woods.

[Ladiesman271]

And you determined that by...










... market survey???

I know of two E.L.M. Aquastar (pre-Bosch takeover) that are still in service with 15+ years on 'em. Don't know of any that out & out died or needed a heat exchanger swap, but it's a pretty small sample size (and only one can I claim the installation on.) They're somewhat finicky PITA units with mechanical feedback that doesn't really modulate well, with a propensity for overheating then self-extinguishing at low flow, but they just won't die (as much as the current owner of one wishes it would. :-) ) I think of them as "reliably finicky". :-) Maybe I live/work in an area with fewer water-harness issues or something(?).




Market survey? He don't need to do no stinkin market survey.

I have the second build of the ELM Aquastar 125 VP. The mechanical feedback modulates well if you calibrate it properly and set the water temperature to about 125 degrees. You have to make sure that low BTU is indeed low. My unit was calibrated a bit on the high side.

All the important parts are still available on line for repair purposes, so who knows how long it will last. Then again, I am not sure if a plumber can handle a simple repair job without a song and a dance about something!

[nhmaster]

I guess I base it on the pile of dead ones that I keep upstairs in the shop so we can rob parts off them for the few that did make it past 10 years. I spose I could take a walk up there and count but I know it's better than 25 and if I add in Paloma Paks its probably in the 35 to 40 range.

Do you think we just make this stuff up for the fun of it.? we are in business to SELL products and make money. If a product is viable and we can make money on it then we gladly sell it.

[master plumber mark]

I hate to say ...... I told you so....



http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm

[Inspektor Ludwig]

Lmao,

Anything that has more than a 3-5 year payback on a house is not worth it! Going green may be a good idea but until it becomes affordable, it doesn't make sense. Thanks for proving what I've been trying to tell people all this time!

[Runs with bison]

It's not "new" though...it's over a year old.

[Runs with bison]

Anything that has more than a 3-5 year payback on a house is not worth it! Going green may be a good idea but until it becomes affordable, it doesn't make sense. Thanks for proving what I've been trying to tell people all this time!

I would love to hear where you are putting your money then, if you scoff at anything making less than 20-33% per year. :p While I'm not a fan of tankless I would set the minimum return a lot lower than that.

[master plumber mark]

I just stumbled onto this info tonight, sorry that
it is about a year old....


no one really beleives any of this "non-green horseshit" from
consumer reports



like I have stated on my web site...

take the money and pack the home with insulation...
install better windows...... THAT is where you gain
a great payback...


INSULATION......this is not very sexy, not very complicated and extremely boring after it is installed...

and its not brain surgery ....

any dumbass can install it. and get a 30% payback forever..

[Runs with bison]

The article is not a bad one, it is one of those I looked at when first evaluating whether or not tankless made financial sense for me. If you want fast payback, use a 1.5-1.6 gpm showerhead instead. Cost is around $30-$50 depending on what you choose. Rate of return is about 100% annually.

However, good luck "packing a home with insulation" and getting a 30% annual return unless it has very little insulation to begin with. While I've done a number of insulation projects, the areas that need it the most often can't be fixed...or if they can, not so easily. Good luck adding insulation thickness cheaply in a cathedral ceiling or uninsulated basement space. And from my own projects insulation is just a minor part of the cost where energy savings are highest. By the time you remove the drywall, insulate, put up new drywall and paint the cost can be quite high and the time investment considerable. The areas that are easiest to add insulation to are open attics...which already tend to have passably high R values to begin with.

It's too bad that the average builder does such a poor job of insulating a home, because it is a lot more expensive to retrofit in places they missed (or skipped and concealed.) Ditto for leaky, uninsulated HVAC duct work.

Windows? Now there is a poor return on investment...unless they have to be replaced anyway. It is really expensive compared to selecting a higher efficiency water heater or higher efficiency furnace. Heck, the payout on a new fridge is probably quicker...and that is really slow. But when replacing anyway, higher efficiency windows make sense.

Besides showerheads, the really easy money is in things like CFL's.

[zl700]

Consumer reports, same mag that has been accused of supporting advertisers, sued and lost on false reports and admitted to incomplete evaluations.
Regarding some posters here, who could trust or respect a person that uses a avitar of a hick or a pic of plumber that's dirty from doing numerous drain cleanings when discussing high-tech on-demand heaters. Installs of advanced Tankless technology is best left to technicians with proper tools, meters and combustion equipment.

[Runs with bison]

It's been a long time since I subscribed to Consumer Reports, but I recall them having a strict policy against advertising. They wouldn't even allow folks to distribute reprints of their ratings on showroom floors which had various salesman complaining when I was shopping for stuff. We couldn't even get permission to use one of their articles as part of a "how to" for a non-profit new homebuyer information seminar.

Not that I think their testing is perfect. They often target different factors than what I find important. They really seem to have dropped the ball on toilets, and consistently so. I've never considered CR to be the be-all, end-all authority. They do however provide an independent evaluation, sometimes right, sometimes wrong.

[master plumber mark]

:D
Consumer reports, same mag that has been accused of supporting advertisers, sued and lost on false reports and admitted to incomplete evaluations.
Regarding some posters here, who could trust or respect a person that uses a avitar of a hick or a pic of plumber that's dirty from doing numerous drain cleanings when discussing high-tech on-demand heaters. Installs of advanced Tankless technology is best left to technicians with proper tools, meters and combustion equipment.

dude, I am sorry that my avatar is not sexy enough for you...

if that is all it takes to earn your trust,
maybe I will change mine,,,....

as far as being a dirty hick business man,
I have had to make payroll for my employees
for well over 30 years now .....every week.


Our great president Obama never has had to ever run a business
or make a payroll, and I would wager that you voted for him..:D.....


Also, I can dress up fine when I need to impress
petty little souls like you


Now does this avatar give you warm fuzzies???

.

[Cookie]

The article is not a bad one, it is one of those I looked at when first evaluating whether or not tankless made financial sense for me. If you want fast payback, use a 1.5-1.6 gpm showerhead instead. Cost is around $30-$50 depending on what you choose. Rate of return is about 100% annually.

However, good luck "packing a home with insulation" and getting a 30% annual return unless it has very little insulation to begin with. While I've done a number of insulation projects, the areas that need it the most often can't be fixed...or if they can, not so easily. Good luck adding insulation thickness cheaply in a cathedral ceiling or uninsulated basement space. And from my own projects insulation is just a minor part of the cost where energy savings are highest. By the time you remove the drywall, insulate, put up new drywall and paint the cost can be quite high and the time investment considerable. The areas that are easiest to add insulation to are open attics...which already tend to have passably high R values to begin with.

It's too bad that the average builder does such a poor job of insulating a home, because it is a lot more expensive to retrofit in places they missed (or skipped and concealed.) Ditto for leaky, uninsulated HVAC duct work.

Windows? Now there is a poor return on investment...unless they have to be replaced anyway. It is really expensive compared to selecting a higher efficiency water heater or higher efficiency furnace. Heck, the payout on a new fridge is probably quicker...and that is really slow. But when replacing anyway, higher efficiency windows make sense.

Besides showerheads, the really easy money is in things like CFL's.


Excellent post.

[Runs with bison]

Our great president Obama never has had to ever run a business or make a payroll, and I would wager that you voted for him..:D.....

And the last president was "elected" by folks like yourself, partially because he was a businessman. Never mind that he had driven various enterprises into bankruptcy. "Arbusto" was the name of one...how appropriate. The one that was successful he was just a figurehead for.

He continued along a "business friendly" course driving our whole nation toward bankruptcy through conservative supply siding principles.

That's not an historical aberration. The previous time this happened conservative businessman Hoover was in charge of the show. In his defense he inherited much of the mess from other conservative presidents. Unfortunately for the country Hoover had 3 years in which not to address the problem "conservative" policies had created. Fortunately Dubya only had 1. The 2 year difference is that between the Great Depression and the Great Recession.

But your silly political blatherings have nothing to do with the economics of such projects.

[Dana]

Uh, dude, "NEW" ???

That hit-job on tankless heaters is over a year old now!

And it's barely worth the toilet-paper it's smeared on, IMHO. Because...

A: They don't state the financial assumptions about fuel pricing or the cost of money- no hint at all about how (or if) they calculated a net-present-value on the cost delta.

B: They overstate hot water usage (which improves the picture for tanks, but is fairly neutral for tankless) at ~20% above the national average for a family of 4 (on which the DOE's EF test was designed)

C: They doped the water to exaggerate liming/scaling effects on a tankless HX. (Hard-water areas really DO need to be mindful, but mine went 15+ years without even a hint of scale issues or any other maintenance on city water in New England, retiring it fully-working when I installed a new heating system that included a buffer tank with an internal HX for the DHW.) It's a useful warning, but irrelevant for the majority of users.

D: They don't address the REAL reasons most peops opt for 'em: Filling huge spas &/or very high volume HW use and space-savings.

E: They don't name the "outside lab", nor do they give any of the raw data and only the vaguest sketchiest description of test methodology, never mentioning size of individual draws (which can degrade the efficiency of a tankless dramatically at the low end) or any other factors other than daily volumes (volumes that are ~20% over the national average for a family of 4., as previously noted.)

This is a hit-job, not a well reasoned analysis. It's designed to overstate the real-world efficiency of a tank, and exaggerate the maintenance issues of a tankless.

Take the efficiency information from people who actually measure stuff without an agenda, and under varying circumstances to determine true average efficiencies for different patterns of use:

http://www.aceee.org/conf/08whforum/presentations/1a_davis.pdf

(Note the above isn't a "rah-rah tankless" piece by any means- a 92% steady-state thermal efficiency condensing tankless only hits ~75% average efficiency in one of the use profiles. Read & ponder. There's a heluva lot more real comparative info there than the CU piece.)

The financials you'll have to do on your own- fuel prices vary by as much as 600% BTU-for-BTU between low-price natural gas markets vs. high price propane markets, and it makes a HUGE difference on if & where the net-present-value boundaries go positive. The one-size-fits-all financial analysis conclusions of the CU piece is utter CRAP!

Will the "average" family even make it back on fuel savings? Depends a lot on the the price of NG over the next decade, (and I'm guessin' not), but fuel savings is about the 4th or 5th reason on the prioritized list of why most people who go tankless make their decisions, behind arbitrarily high draw volume (not to be confused with high flow) & space savings (the two most cited, in my limited experience), and appliance longevity (a distant 3rd.)

They also don't compare some of the better low-end cheap to install versions that are ~80% efficient (eg: Bosch 1600H), which still beat tanks soundly on average efficiency, but are nowhere near as complex or expensive to install as Noritiz & Takagis. (Atmospheric draft therefore B-venting OK, ignition powered by water flow so it needs no electricity, etc.) NPV on those looks pretty good for most propane users, if you can tolerate the 30-117KBTU modulation range. It's good enough for a single-shower even in cold-water country, maybe two in FL or SoCal but it's HX is fairly high-head, not designed for super high flow on the water side. It's about right for weekend cabins & condos, etc.- VERY low maintenance.)

BTW: Don't confuse me for a huge tankless fan- I fully understand their merits & limitations (I think they make better modulating combi space-heating/DHW boilers than water heaters, even if they're more efficient than tanks.). Still, I've yet to meet anyone who has lived with one for awhile who is dying to go back to a tank. But that consumer-reports piece is a downright LOUSY bit of analysis, and gives the reader no tools or information by which to analyze whether it makes sense for them, and how they use hot water.

[zl700]

Love the new Avitar!

[master plumber mark]

Love the new Avitar!

It makes my day that you like the new avatar...

,
Tankless Dudes,.......

and I am sorry that this is not
"new information" but none of you have ever
posted it to this site before,
and for well over a year now its been out.....


so I suppose its "new" for here.

I guess if consumer reports does not praise tankless,
you must discreit the source....


It seems pretty legit to me
and you can take it or leave it...

I am just the messenger, I did not make this stuff
up just to piss all you tankless dudes off....


as far as political talk goes, what has
our currency been driven down to today???.


does my new avatar make me seem more credible??

[Runs with bison]

as far as political talk goes, what has our currency been driven down to today???

That illustrates the problems with conservatives. They sound as if they were born yesterday. :p Our currency went in the dumpster quite some time ago, the run up in gold and oil should have clued you in several years ago. Folks like me saw this coming back in 2000. ;) Now, after a lost decade conservatives still don't get it.

To get rid of the Bush deficit legacy our currency is going to become a lot less valuable over the coming years. Call it the Dubya Tax...it hits those of us who actually saved, not the dipsticks that overleveraged themselves in a "ownership society" that was really a "debtor society"...now a "receivership society."

There is only so long the Fed and the rest of the world can hold down our interest rates. The future was mortgaged over the past 8 years...we're just renting until the Chinese foreclose.

What we need is Volcker calling the shots IF/when we pull out of this recession. He's the one that deserves credit for slaying stagflation back in the 80's. There's a whole lotta elephant manure to clean up.

[master plumber mark]

That illustrates the problems with conservatives. They sound as if they were born yesterday. :p Our currency went in the dumpster quite some time ago, the run up in gold and oil should have clued you in several years ago. Folks like me saw this coming back in 2000. ;) Now, after a lost decade conservatives still don't get it.

To get rid of the Bush deficit legacy our currency is going to become a lot less valuable over the coming years. Call it the Dubya Tax...it hits those of us who actually saved, not the dipsticks that overleveraged themselves in a "ownership society" that was really a "debtor society"...now a "receivership society."

There is only so long the Fed and the rest of the world can hold down our interest rates. The future was mortgaged over the past 8 years...we're just renting until the Chinese foreclose.

What we need is Volcker calling the shots IF/when we pull out of this recession. He's the one that deserves credit for slaying stagflation back in the 80's. There's a whole lotta elephant manure to clean up.




------------------------------------------------------------

Runs...
who told you I was a conservative??

Me and Ian are " best buddies liberals"
go ahead and just ask him some time....

so are you saying

If you own a business ,
and go to work every day on time and sober ,,,
then you have to be a conservative??.

.

if you saw this comming 10 years ago, I assume
you also invested heavily in gold when it was 375 per ounce??

right??.

[Runs with bison]

if you saw this comming 10 years ago, I assume you also invested heavily in gold when it was 375 per ounce??

I've stayed out of gold and intend to since it is a speculative thing with much less intrinsic worth in today's world. It is flat or down most of the time...waiting for gold to spike is like waiting on someone to die to collect an inheritance: it is both morbid and unhealthy for the soul. Trying to time this sort of run up relies on skills that few mortal men possess, myself included. As the old saw goes, "the market can remain irrational far longer than you can remain solvent."

However, I have done far better in the Great Recession than all but a few of the best Bear Market funds. I subscribe to the "get rich slowly" approach rather than chasing the fast buck. "Buy and hold" is for suckers with this fraudulently structured market...as I learned the hard way at the first of the decade. That's why I'm still on target for retirement in my mid 50's despite the so called "lost decade."

[master plumber mark]

[quote=Runs with bison;232127]I've stayed out of gold and intend to since it is a speculative thing with much less intrinsic worth in today's world. It is flat or down most of the time...waiting for gold to spike is like waiting on someone to die to collect an inheritance: it is both morbid and unhealthy for the soul. Trying to time this sort of run up relies on skills that few mortal men possess, myself included. As the old saw goes, "the market can remain irrational far longer than you can remain solvent."

quote]

On this I totally agree with you....
most specualtion of any kind and in gold is actually morbid and unhealthy for the soul.....

[ChuckS]

Our great president Obama never has had to ever run a business
or make a payroll, and I would wager that you voted for him..:D.....

He had a payroll during the campaign. No, he didn't have to struggle to make it but he technically had one.

[Runs with bison]

Mark,

I don't disagree with you or Consumer reports about some of the negatives of tankless. A true tankless is not an ideal solution. Having some recirc/surge volume is needed to make them fully user friendly...which moves away from the fully tankless. In the end some sort of hybrid mini-tank makes more sense to me. The high burner rate is the key problem/expense I see with regards to venting, primarily when considering an upgrade retrofit. Scaling is a regional matter and important maintenance consideration. (My water's hardness is borderline, probably OK, while where I grew up was incredibly hard...hell on electric water heater elements and I would never even consider tankless with it.) Figuring out how to evaluate the relative maintenance expense is not easy. Some of it depends on how DIY competent the homeowner is.

But where I come down on this, insulation, windows, water heater jackets, passive solar waterheat, etc. is the need to do a reasonable, objective, economic evaluation of the cost vs. the benefits. This and performance aspects have moved me away from tankless. I'm already at usage levels that are on par with tankless, so the benefits of conversion for me are far less than average.

Al Gore doesn't figure into it. I'm looking for a full economic justification.

[Cass]

Gold hit $1160.00 today up from $750 a year ago...not a bad increase for an investor...

[Peter Griffin]

This entire thread is proof positive that going green and politics are intimately entwined with each other.

Mark, I wonder how many folks realize that that RUUD tank in your avatar was possibly the first tankless water heater eer marketed and that it is close to a hundred year old technology. ?

The great tankless debate rages on but I have noted that in the past year, sales have dropped for all models. Either because of the lagging economy or consumer awareness.

[Cass]

While gold to a degree is good for trading...in an emergency situation you can't eat it, burn it, defend your self with it, or do any thing with it but trade...and then only to someone who wants it...in my way of thinking water, food, fule, clothing, shelter, guns, ammo, and things like that are more valuable than gold in an emergency...if we were still on the gold standard then I would have a little different view...

[Dana]

This entire thread is proof positive that going green and politics are intimately entwined with each other.

Mark, I wonder how many folks realize that that RUUD tank in your avatar was possibly the first tankless water heater eer marketed and that it is close to a hundred year old technology. ?

The great tankless debate rages on but I have noted that in the past year, sales have dropped for all models. Either because of the lagging economy or consumer awareness.

Who said tankless is about going green?

Near as I can tell tankless sales in the US are mostly about the UNDULGENT SPLENDOR of endless showers & 150 gallon spas, not 82% vs. 58% efficiency.

If it happens to be somewhat more efficient in lower volume use as well, so what? People who buy a tankless on some green-factor theory (I've yet to actually meet one of those) would have to be people who can't/don't do math. For the money there are usually other places where homeowners can get better return on carbon emission reductions etc per buck.

[Dana]

This entire thread is proof positive that going green and politics are intimately entwined with each other.

Mark, I wonder how many folks realize that that RUUD tank in your avatar was possibly the first tankless water heater eer marketed and that it is close to a hundred year old technology. ?

The great tankless debate rages on but I have noted that in the past year, sales have dropped for all models. Either because of the lagging economy or consumer awareness.

I thought it was Vaillant, not Ruud that came up the the controlled temp tankless. They've been at it since inventing the first temperature controlled closed-systems (separating flue gases from the water) in the mid-1890s, and are pretty much credited with the wall-hung copper-tube-boiler flavored versions (1905?) that are direct technical ancestors of what we see today.

Copper tube boilers & water heaters are still Vaillant's main biz. Never seen 'em in the US, but they're major players in Germany & the Netherlands, with a good market share in the UK as well.

Ruud is credited with the invention of automatic/thermostatically controlled storage tank HW heaters, somewhere around 1890. I'm not sure when they got into the tankless biz, but since Vaillant held the early patents, I suspect it was after 1910.

[Inspektor Ludwig]

Well,
There ya go! It all depends on what you want I guess. Endless hot water or going green? The idea of efficiency is not clear to the average homeowner. Some will believe that if they install a $3000.00 tankless water heater that they're going to save so much a month on their energy bill. Does the benefit outweigh the cost? How long will it take me to recoup the $3000.00? How long am I planning on staying in this house. If you're looking for cost savings then no, it wouldn't make sense unless you plan on living in your house for long, long time. Energy savings is more than just a tankless water heater, it has to be a complete package for it to work in the black. Insulation is probably the easiest, cheapest most effective way to save money on your energy bill. That's were I'd put my money first. Turning down the thermostat is another. Unplugging battery chargers, etc. Shower heads are already low flow, been that way for years. But who has the money to do the whole envelope? Commercial properties make their decisions the same way, what is the payback? 5 years, 10, 20? No business would ever give a p.o. for equipment with a 20 year payback. 5-7 is the standard range which makes financial sense. Homeowners would be 3-5 which again, makes financial sense. Only when technology and products become more affordable for homeowners and developers will we start to see some amazing changes for the better. I look forward to it.

[D'Brie]

Up-front costs are high
The tankless water heaters we tested cost $800 to $1,150, compared with $300 to $480 for the regular storage-tank types. Tankless models need electrical outlets for their fan and electronics, upgraded gas pipes, and a new ventilation system. That can bring average installation costs to $1,200, compared with $300 for storage-tank models.

Wow, we'll normally charge 2-3 times these stated costs. I wonder where CR gets their install cost information?

[master plumber mark]

Up-front costs are high
The tankless water heaters we tested cost $800 to $1,150, compared with $300 to $480 for the regular storage-tank types. Tankless models need electrical outlets for their fan and electronics, upgraded gas pipes, and a new ventilation system. That can bring average installation costs to $1,200, compared with $300 for storage-tank models.

Wow, we'll normally charge 2-3 times these stated costs. I wonder where CR gets their install cost information?


in our town the tanklessare being installed for somewhere between 2900 and 4900

normal tank heaters around 800...

I think that they use the bare min numbers...
I dont know why....

[Runs with bison]

Wow, we'll normally charge 2-3 times these stated costs. I wonder where CR gets their install cost information?

Are you doing open heart surgery while you are there? A 2-3x factor is ridiculous.

[master plumber mark]

looks like I missed that back in o8...

but their was never actually a link to the report

perhaps I thought it was just a rant by nymaster..??

Lot of rants here that I try to avoid...and not read .....


the report is not going to make any difference anyhow...

because once you go green,,,,

cold hard facts dont matter..

[Dana]

looks like I missed that back in o8...

but their was never actually a link to the report

perhaps I thought it was just a rant by nymaster..??

Lot of rants here that I try to avoid...and not read .....


the report is not going to make any difference anyhow...

because once you go green,,,,

cold hard facts dont matter..

Speakin' of not letting the facts confuse...

To you have any evidence that fuel/carbon savings is anything like a primary driver of tankless sales? (I've not seen any, but maybe it exists.) It may be a primary reason for various subsidies, but there's great debate amongst regulator wonks as to whether the subsidy is appropriate for the (lack of anticipated) fuel savings.

You seem convinced that a primary motive of tankless buyers is some green-factor, whereas in my informal completely non-scientific sampling the primary reason people actually buy 'em is to go hog wild with hot water use, filling gia-NORMOUS soaking tubs & spas, etc., which is kinda the opposite of "green", eh? Continuous uninterrupted DHW flow capability makes tankless heaters a water and fuel waste enabling technology (and as every tankless owner who is also the parent of a teenager knows, it achieves that end very well! :-) )

But don't let those facts confuse you, eh? ;-) Go ahead and keep chalkin' it up to stupid greenies who can't do math or somethin'... (Or dig up the data to support that perception, 'cuz I just don't see it.)

The cold hard FACTS are, it takes a heluva tank (or multiple tanks) to fill multiple monster tubs in the McMansion, but one tankless will do, and the people who buyin' 'em know that (whether they know/care about the relative efficiency aspects or not.) And the peops in the tiny townhouses know they can buy some precious floor space back with a tankless, mounting it on the wall over the washer, etc. Those two reasons cover the vast majority of the residential tankless installations I've seen.

The only installation I personally know of where fuel economy was a primary motivator was commercial, not residential, and also made sense given the required flow & volume and again. Green had nothing to do with it, even if it was arguably greener than their prior solution: Keeping a high mass oil fired boiler hot just to make hot water on an intermittent basis had atrocious standby cost. (It would have taken a heluva tank to handle that too.)

I challenge your presumption- show me some facts!

[master plumber mark]

Speakin' of not letting the facts confuse...

To you have any evidence that fuel/carbon savings is anything like a primary driver of tankless sales? (I've not seen any, but maybe it exists.) It may be a primary reason for various subsidies, but there's great debate amongst regulator wonks as to whether the subsidy is appropriate for the (lack of anticipated) fuel savings.

You seem convinced that a primary motive of tankless buyers is some green-factor, whereas in my informal completely non-scientific sampling the primary reason people actually buy 'em is to go hog wild with hot water use, filling gia-NORMOUS soaking tubs & spas, etc., which is kinda the opposite of "green", eh? Continuous uninterrupted DHW flow capability makes tankless heaters a water and fuel waste enabling technology (and as every tankless owner who is also the parent of a teenager knows, it achieves that end very well! :-) )

But don't let those facts confuse you, eh? ;-) Go ahead and keep chalkin' it up to stupid greenies who can't do math or somethin'... (Or dig up the data to support that perception, 'cuz I just don't see it.)

The cold hard FACTS are, it takes a heluva tank (or multiple tanks) to fill multiple monster tubs in the McMansion, but one tankless will do, and the people who buyin' 'em know that (whether they know/care about the relative efficiency aspects or not.) And the peops in the tiny townhouses know they can buy some precious floor space back with a tankless, mounting it on the wall over the washer, etc. Those two reasons cover the vast majority of the residential tankless installations I've seen.

The only installation I personally know of where fuel economy was a primary motivator was commercial, not residential, and also made sense given the required flow & volume and again. Green had nothing to do with it, even if it was arguably greener than their prior solution: Keeping a high mass oil fired boiler hot just to make hot water on an intermittent basis had atrocious standby cost. (It would have taken a heluva tank to handle that too.)

I challenge your presumption- show me some facts!











ENDLESS HOT WATER...
WITH NO DOWNSIDE WHAT-SO-EVER...



Dana.....they will sell like hotcakes...

[Dana]

Uh, dude...

http://www.noritz.com/homeowners/products/tankless_advantage/#1

http://www.rinnai.us/tankless-water-heaters/

http://www.takagi.com/index.php?p=products.php&page_id=2&category_id=1

"Endless hot water" is not a new theme in the industry- it's the standard first line in the sales pitch.

On the Noritz pitch energy savings (in green) was what, #5?

[Nate R]

My primary motivation for looking at them was space savings. I didn't care if we saved fuel or used a bit more, I knew it'd be fairly close to the same.

Our 30 gal gas heater won't fill the tub. This is the only problem with it. We figured instead of trying to squeeze a 40 in a nearly too small space, put in a tankless in another spot and use the old WH space for a tiny utility sink.

[Dana]

My primary motivation for looking at them was space savings. I didn't care if we saved fuel or used a bit more, I knew it'd be fairly close to the same.

Our 30 gal gas heater won't fill the tub. This is the only problem with it. We figured instead of trying to squeeze a 40 in a nearly too small space, put in a tankless in another spot and use the old WH space for a tiny utility sink.

How UN-green and ignorant of you! :)

My primary reason (16 years ago) was tub-filling, followed by space savings, followed by longevity & low catastrophic leak potential compared to tanks. With standing pilot ignition and a 78-80% raw combustion efficiency it was no super-saver but it probably paid for itself in fuel savings in that time frame (and if history at this house was any guide, I would have been replacing a tank before now anyway.)

I only retired the tankless when I retired the 5x oversized cast-iron boiler, to be replaced by a Takagi KD20 tankless, used as a wall hung boiler, serving a reverse-indirect to buffer newly implemented micro-zoning and provide DHW.

Were I totally kermit-complected I might have run a mod-con instead, but the calculated fuel savings of the higher efficiency didn't go NPV+ within the anticipated lifetime of the mod-con. (Lessee, a $400 surplus tankless, or a ~$2800 mod-con, that's a $2400 cost delta... at $80-150/year annual fuel savings, assuming 3% discount rate... nope, still negative at 20 years)

And the tankless gives me WAY more first-hour gallons than an appropriately sized mod-con would. Without running it even as high as 1/2-modulation, with a drainwater heat exchanger feeding the indirect I get "endless hot water" at a ~4gpm gusher in showering mode, and can still comfortably fill the tub using the thermal mass of the indirect, maintained at a modest 130F (heating temp required by the radiation on design day, so WTF, use that temp for the DWH and forget about it). Even when pulling heat out of it at ~1.5-2x the design day with an air handler coil (the 2nd stage of a 2-stage zone) showers run forever with the tankless, but might eventually become tepid with a tiny mod-con.

So, with a tankless running as a boiler I can waste all the hot water I want- SUCCESS!! :D

And if the miserable Takagi beast craps out in only 5-10 years I can replace it with another $500 tankless (maybe even a cheap condensing version will be available by then) and still be $ ahead. If the price of fuel quadruples in the short term I can revisit the present-value of a mod-con against future savings, but the indirect/buffer and will stay integrated with the heating system (return water from radiation at the bottom of the tank is well in to condensing temps under a real heat load, as well as when under heavy DHW load. It'd average over 90% combustion efficiency, if not over 95% but would suffer very low cycling losses.)

But the last thing I'll be buying is another standalone tank, eh? ;-) (Not that there's anything WRONG with that...)

[ChuckS]

My primary motivation for looking at them was space savings. I didn't care if we saved fuel or used a bit more, I knew it'd be fairly close to the same.

Our 30 gal gas heater won't fill the tub. This is the only problem with it. We figured instead of trying to squeeze a 40 in a nearly too small space, put in a tankless in another spot and use the old WH space for a tiny utility sink.

Take my advice, unless you can centrally locate the TWH close to each of the facets then don't do it. It will only frustrate you waiting for the hot water and/or waiting on the sandwich.

We made our acceptable with a recirc loop that turns on automatically when the HW is used but it weren't for that we'd be very unhappy.

[jnyost]

I've never had any "cold sandwich" problems with my Takagi TK-2.

Is it perfect, no. Does it fill my large tub and allow me to have 3 showers going at once? Yes. It may get replaced in the future but I have to get something large enough for that occasional tub fill. I'm currently looking at different solutions as we added onto our house and it's too long for one heater. It takes a long time for the water to reach the addition from the old location.

[Dana]

I've never had any "cold sandwich" problems with my Takagi TK-2.

Is it perfect, no. Does it fill my large tub and allow me to have 3 showers going at once? Yes. It may get replaced in the future but I have to get something large enough for that occasional tub fill. I'm currently looking at different solutions as we added onto our house and it's too long for one heater. It takes a long time for the water to reach the addition from the old location.

The coldwater sandwich effect varies with make & model, the temperature of the incoming water, the temperature of the incoming combustion air, and the sensitivity of the user. Some have inordinately long startup times which makes it dead-obvious, but none of the big 3 (Noritz, Rinnai, & Takagi) that I've used have truly egregious models.

Old-skool 78-80% standing pilot versions have NO discernable coldwater sandwich (no flue purge, no ignition delay= no problem!)

TK2s use room air for combustion, so if it's in a 65-70F house the chilling effect of the flue purge & resulting coldwater sandwich is dramatically LESS than it's twin-sister the (sealed combustion direct-vented) KD20 in mid winter when it -5F out, but about the same in the warmer months. (Me, I don't care- my KD20 is only sending those 6-8 ounces of cooler water to a 48 gallon buffer tank of ~130F water, never to a handwashing faucet. :-) )

The coldwater sandwich issue is real, but not nearly as obnoxious in most cases as the tankless critics make it out to be. (It's a princess & pea thing, IMHO.) The flameout & loss of temperature regulation at very low flow in warmwater areas is a bigger deal, but even that isn't very significant (rare, if your lowest modulated input is 20K or less.)

[jnyost]

The coldwater sandwich effect varies with make & model, the temperature of the incoming water, the temperature of the incoming combustion air, and the sensitivity of the user. Some have inordinately long startup times which makes it dead-obvious, but none of the big 3 (Noritz, Rinnai, & Takagi) that I've used have truly egregious models.

Old-skool 78-80% standing pilot versions have NO discernable coldwater sandwich (no flue purge, no ignition delay= no problem!)

TK2s use room air for combustion, so if it's in a 65-70F house the chilling effect of the flue purge & resulting coldwater sandwich is dramatically LESS than it's twin-sister the (sealed combustion direct-vented) KD20 in mid winter when it -5F out, but about the same in the warmer months. (Me, I don't care- my KD20 is only sending those 6-8 ounces of cooler water to a 48 gallon buffer tank of ~130F water, never to a handwashing faucet. :-) )

The coldwater sandwich issue is real, but not nearly as obnoxious in most cases as the tankless critics make it out to be. (It's a princess & pea thing, IMHO.) The flameout & loss of temperature regulation at very low flow in warmwater areas is a bigger deal, but even that isn't very significant (rare, if your lowest modulated input is 20K or less.)

My TK-2 is in my unfinished basement at a fairly constant temperature. It's not anywhere near the temps of 65-70f but it's not near outside freezing temps either.

I'd love to hear about your setup if you don't mind sending me a PM. I'm needing some hot water changes soon.

[vincent11]

I'd appreciate advice in my situation on whether to go with a tank or tankless.
My water tank is outside in a metal shed, with outside temperatures at the lowest in winter just around freezing (32 degrees) to a high of a little over 100 degrees in summer. My water heater is located directly next to the gas meter, which the gas company doesn't like because it lies within three feet of their meter (flame source in case of leaks at the meter, I guess). Tankless prices are about $2000 to $2500 for a reputable installer installing a takagi, noritz or rinnai, utilizing one of their outdoor units. We have two bathrooms, just my wife and I live there with the occasional visitor. We don't have a high use water item except for a regular tub or shower. I think I can at most squeeze in a 50 gallon tank with 1 inch of insulation around it or a 40 gallon with two inches of insulation. Right now we run the old hot water tank to about 135 degrees in the 10 year old tank we use right now in order to supply us with enough hot water for our needs. A new one hopefully would not need to be run that hot. Until recently, I didn't even know you were supposed to drain the tank once a year. It has never been drained. What the he** do I do?

[Dana]

I'd appreciate advice in my situation on whether to go with a tank or tankless.
My water tank is outside in a metal shed, with outside temperatures at the lowest in winter just around freezing (32 degrees) to a high of a little over 100 degrees in summer. My water heater is located directly next to the gas meter, which the gas company doesn't like because it lies within three feet of their meter (flame source in case of leaks at the meter, I guess). Tankless prices are about $2000 to $2500 for a reputable installer installing a takagi, noritz or rinnai, utilizing one of their outdoor units. We have two bathrooms, just my wife and I live there with the occasional visitor. We don't have a high use water item except for a regular tub or shower. I think I can at most squeeze in a 50 gallon tank with 1 inch of insulation around it or a 40 gallon with two inches of insulation. Right now we run the old hot water tank to about 135 degrees in the 10 year old tank we use right now in order to supply us with enough hot water for our needs. A new one hopefully would not need to be run that hot. Until recently, I didn't even know you were supposed to drain the tank once a year. It has never been drained. What the he** do I do?

Given your relatively low water use it's unlikely that you'd ever recoup the upfront cost differential between tank/tankless in fuel savings unless natural gas sees some serious fuel price inflation over the next decade.

Still, efficiency bang for upfront $$ spent, in Glendale CA you're likely to do much better with low cost batch-solar pre-heat like the Harpiris SunCache (http://www.harpiris.com/home.html) or their competitors, and a well insulated electric tank. After CA and federal incentives the installed cost would be similar to or less than a fossil-fired tankless, and with the extremely low standby losses of an electric tank (as compared to a NG or propane tank), you'd see a greater than 50% reduction in annual water heating costs. Most of the year the electric tank would be drawing zero watts except during periods of heavy water use, as the water entering the tank woud often be hotter than what's stored there (particulaly if you timed your water use well.) The downside is, that under VERY heavy use the recovery period would be fairly long. A more expensive alternative without recovery time issues would be to use an electric tankless in conjunction with batch pre-heat (but that may require an electric panel or service upgrade.)

With either of these scenarios it would need a tempering valve/thermostatic-mixing valve at the output of the electric heater since there will be times where the batch heater is well into the "scald me now" temperature range.

[vincent11]

Thanks for the quick reply Dana. I didn't think of a Solar pre-heat. More research. Lucky I am not time pressed at the moment. I actually thought that because I was outdoors, my standby losses were so great that tankless would pay for itself. If not, there seems no reason to do so.

[Dana]

Thanks for the quick reply Dana. I didn't think of a Solar pre-heat. More research. Lucky I am not time pressed at the moment. I actually thought that because I was outdoors, my standby losses were so great that tankless would pay for itself. If not, there seems no reason to do so.

Your standby losses due to being outdoors are higher in winter, lower in summer, but the average annual temp in Glendale/LA is about 65F. Even though peak days the standby can be substantially greater than non-peak, on average it's pretty much a wash- a 5F increase in delta-T over having it inside, for about a 8-10% increase in average standby. If you're currently burning 250therms/year in a 0.60EF tank it might bump to 260 or so (not more) by installing the tank outdoors. Going tankless would drop you to 175-225 therms per year, but with batch solar pre-heat you'd drop to about 50-100 therms, maybe less.

Standby losses for gas fired tanks are several times higher than electric tanks due to convection from the central flue/heat exhchanger and necessary clearance gaps in the insulation. If you opt for solar pre-heat you may get more benefit out of it with an electric tank, but a forced-draft higher efficiency tank might still be cheaper to run, depending on your utiltiy rates. Even if you burned as much as 75 therms/year (50 in standby loss) it might still be cheaper than heating the solar shortfall with electricity. If water heating is your primary gas use during spring/summer/fall (and it likely is), you can probably get a good handle on how much fuel you're using, and what your likely savings/costs would be with different options.

[vincent11]

Thanks, Dana.

That's the kind of information that I need.

[jasonboler]

Thanks to all for the your advices! You share very useful thing for me

[aoser331]

Great post. Thanks for all the info...a lot of food for thought here. I haven't installed one myself, but the owner of my company is trying to push these, due to government special tax breaks...I hadn't considered a lot of the things you mentioned at all, it seems you have a valid argument against these things...at least for the time being...

[Tankless Adviser]

In my effort to help keep beating this dead horse, here is a chart comparing different types of water heaters and estimate costs.
http://www.aceee.org/consumerguide/waterheating.htm#lcc

Do the installed costs line up?

Did you notice anything missing from the list? Condensing tankless is nowhere to be found. With PVC 636 venting of condensing tankless, I wonder what the installation costs comparison will look like.