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Thread: Tankless info from consumer reports, Tankless...Bahhhhh

  1. #1
    Master Plumber nhmaster's Avatar
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    Default Tankless info from consumer reports, Tankless...Bahhhhh

    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 evenólonger 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 ó 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.

  2. #2
    Plumber jimbo's Avatar
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    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.

  3. #3
    Illinois Licensed Plumber SewerRatz's Avatar
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    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/...eets/115-B.pdf

  4. #4
    Senior Robin Hood Guy Ian Gills's Avatar
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    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.
    Last edited by Ian Gills; 12-29-2008 at 09:43 AM.

  5. #5

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    Quote Originally Posted by nhmaster View Post

    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!


    .
    Last edited by Ladiesman271; 02-23-2009 at 07:32 PM.

  6. #6
    Plumber Cass's Avatar
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    Yup...this echos everything that has been mentioned here since they first started becoming popular...

  7. #7
    DIY Member JAR8832's Avatar
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    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.

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    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).

  9. #9
    DIY Senior Member Fubar411's Avatar
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    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.

  10. #10

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    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.
    "Dude, we can fix that. My old man is a TV repairman, he's got the ultimate set of tools!" --Jeff Spicoli


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    Quote Originally Posted by Fubar411 View Post
    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.

  12. #12
    Extreme DIY Homeowner Scuba_Dave's Avatar
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    I don't have gas to the house, so tankless wasn't an option
    I need my 200a service for my Christmas display
    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
    DIY Handyman (not 4 hire)
    I have enough to do to my own house

  13. #13
    Retired Defense Industry Engineer jadnashua's Avatar
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    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.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Quote Originally Posted by jadnashua View Post
    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.

  15. #15

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    Quote Originally Posted by jadnashua View Post
    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!

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