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View Poll Results: Tank or tankless?

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  • Tankless

    14 48.28%
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    10 34.48%
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Thread: If install cost wasn't an issue...

  1. #1
    DIY Junior Member
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    Post If install cost wasn't an issue...

    How many here - based on daily usage and ongoing cost factors - would prefer a tank-less over a tank?

    Take out of the equation the initial cost of a tank, AND the initial cost of install and also consider using a decent quality (not top of the line, not cheap either) WH... I'm only asking because the house I bought has a seller credit of $3,000 for a tankless (or tank, if I want, and then I can use that money elsewhere). We fought for the credit, and originally wanted it. Every once in a while we have 2nd thoughts, but it's just about too late to back out since we have a plumber coming to install a tankless next week (Rinnai R94LSI).

    Thoughts?

  2. #2
    In the trades Dana's Avatar
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    Don't worry, be happy. A tankless WILL be more efficient, only if you have 3 showers in the house that are likely to be running at the same time, or if you have fairly hard water it would it be way less than ideal. Rinnais are definitely quality goods- I wouldn't sweat it. The biggest operational issue with the R94LSI would be late-summer very low flow temperature regulation when the incoming water temps peak, since it's lowest fire is 15K, but that's as good or better than most- it'll be fine. Just be sure to clean the filter at least once/year (put it on the calendar).

    If your unsure about the hardness your water supply have your water tested for hardness. If it's under 1 grain, forget about it- not a problem, between 1-5 you may have to descale it every few years. If it's over 10 you may have to descale it annually or more often to keep it up to snuff. (Installing isolating ball valves and taps for descaling ports at the same time that you install the HW heater isn't a bad idea in hard-water location installations. You need to be able to run a mild-acid rinse trough it- there are commercial descaling/deliming solutions are available, but dilute vinegar can work if you're too cheap.)

    But if you have any sort of hydronic (pumped hot water) heating system, an indirect-fired HW tank running off the boiler would usually be a better (cheaper, lower maintenance, yet still high-output & high-efficiency) choice.

  3. #3
    DIY Senior Member Runs with bison's Avatar
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    Low flows could be a problem for me with tankless as would some other aspects. If install cost was not a concern I would opt for a condensing tank water heater. The Btu input is similar to that of a tankless, but without the pitfalls. The overall difference in efficiency is likely to be negligible.

  4. #4
    In the trades Dana's Avatar
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    Quote Originally Posted by Runs with bison View Post
    Low flows could be a problem for me with tankless as would some other aspects. If install cost was not a concern I would opt for a condensing tank water heater. The Btu input is similar to that of a tankless, but without the pitfalls. The overall difference in efficiency is likely to be negligible.
    Kinda depends- look a the difference between the condensing tank (heater #4) and the condensing tankless (heater #6) under differing use profiles (particularly under low-volume use profile):

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

    The condensing tankless' performance under low use was about where the condensing unit lived at HIGH volume use(!). We can speculate as to why that was, and how to mitigate it in real-world installations, but high combustion efficiency can never overcome standby loss, and the lower the volume of use, the higher fraction of the total that standby loss represents.

    The dedicated installer can dramatically reduce standby loss, but I've yet to meet one of those in the plumbin' trades. Near-water-heater or boiler plumbing insulation is (almost) invariably left as an exercise for the building/home owner.

    But that fancy Euro modulating-condensing stratified tank job (heater #5)...

    It's probably a small fortune, but if cost is no object, the true efficiency is there!

  5. #5
    DIY Senior Member Runs with bison's Avatar
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    That's just an awful way to present the data, really not very useful. Put it in terms of where the losses go and you have something. The storage loss is essentially a fixed quantity...and isn't that much in a well designed condensing unit. About the only conclusion he had was the most obvious and didn't require ANY testing.

    What's particularly troublesome for tankless is that one must start adding various small tanks to make it work comfortably by comparison. Kind of defeats the purpose. To get storage like real world performance, you need some sort of storage. Not much of a surprise I suppose.

    Too many compromises with the tankless for my tastes. The potential savings just aren't enough, especially when the paraphenalia are added to the tankless to make it palatable...and therefore efficiency is reduced.

  6. #6
    Journeyman/Inspector Inspektor Ludwig's Avatar
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    This is something I've really thought about. I like the idea of endless hot water since I'm in a family of 4! What kills me is the people who want a tankless because it's the green thing to do but love to tell you how they never run out of hot water when they take a 45 minute shower! Not so green. We live in an earthquake zone not to mention we have a few Mountains that like to blow and now a dam that might burst. The state keeps talking about being prepared in an emergency. I have 50 gallons of fresh water to use just in case something does happen. That's the big reason why I'm keeping my tank.

  7. #7
    Apprentice Plumber D'Brie's Avatar
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    Quote Originally Posted by Inspektor Ludwig View Post
    This is something I've really thought about. I like the idea of endless hot water since I'm in a family of 4! What kills me is the people who want a tankless because it's the green thing to do but love to tell you how they never run out of hot water when they take a 45 minute shower! Not so green. We live in an earthquake zone not to mention we have a few Mountains that like to blow and now a dam that might burst. The state keeps talking about being prepared in an emergency. I have 50 gallons of fresh water to use just in case something does happen. That's the big reason why I'm keeping my tank.
    I live here in NW Washington too and I like to be prepared. Having a 50 gallon tank of water can be a good thing. No power = no problem but a tankless water heater can use less energy too.

  8. #8
    DIY Member ChuckS's Avatar
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    Quote Originally Posted by Inspektor Ludwig View Post
    This is something I've really thought about. I like the idea of endless hot water since I'm in a family of 4! What kills me is the people who want a tankless because it's the green thing to do but love to tell you how they never run out of hot water when they take a 45 minute shower! Not so green. We live in an earthquake zone not to mention we have a few Mountains that like to blow and now a dam that might burst. The state keeps talking about being prepared in an emergency. I have 50 gallons of fresh water to use just in case something does happen. That's the big reason why I'm keeping my tank.
    This is what I've noticed also. I bought our tankless because we had a gas lowboy in the crawl space and those are no longer made. From my perspective, a tankless is only green if there is a single guy living in the house. I say that because he'll take one or two reasonable showers and maybe wash a dish once a week. I've even adjusted to washing my hands with cold water.

    My wife and daughter are a different story, they now take very long showers and turn on the hot water for just about anything. I installed a recirculation loop that only kicks on when hot water is used but unfortunately, the loop has to come up to temp before it shuts off. This means a lot of wasted energy for a quick hand wash etc...

    I gave up on trying to get them to use cold for quick things so now I pay more for energy and water (looooooong showers)...

  9. #9
    Journeyman/Inspector Inspektor Ludwig's Avatar
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    That's what I'm afraid would happen too! I'd buy a tankless and spend an hour in the shower, not much money saved there!

  10. #10
    Master Plumber Dunbar Plumbing's Avatar
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    That's what is happening most times; tankless provides the excuse to waste water with the fringe attitude that it's a cost saver because it's not heating stored water.

    99% of the tankless units installed are in homes where the property owner does not know how to work on them. It's a guessing game from the word go.

    Does not matter if they have the internet at their disposal; if something happens to them, or if they move, die or become unable to work on that unit to save a buck...

    that pushes either the next owner, the wife, or talking to 6 neighbors and one that has a box of tools to try and figure out what makes that box on the wall tick.


    But I get defensive statements thrown at me when I write like this, the ones who spent hours upon hours on their tankless purchase going over everything and proud they hung that unit on the wall. That's great, it's admirable...but remember the down-the-road costs.

    You do not have parts at your disposal most times. Especially years later after the model on the wall is 4 models changed since then.


    In a house with no hot water for days.....against a house with no hot water for hours is a BIG difference, completely.

    Of course; I'm talking of the down side to these equations regarding tankless...but I'm a service plumber. I'm the guy everyone calls when there's big problems in little china and the world has stopped at your doorstep until the plumbing is fixed.

    So when I see any product relating to plumbing, I have to know how it breaks, what it costs, what I need to do to make that product reliable.


    I know if I am dealing with a Kohler faucet...be prepared for misery and let down. It's coming. Multiple trips and no guarantee that even the new products straight from Kohler themselves is going to work. Si? Si.


    Everybody loves new technology, wants to be part of the "wave" and tankless will give you that. They are a sure bet out west; if the incoming temperature of the water is relatively high to begin with, these units do a good job, a great job because the temp rise is less than 40 degrees to do so.

    Come out to the eastern states, northern states and that's where you'll find out that 50/60/70 degree temp rises are the norm...and that takes a flame thrower on the wall to keep that water moving fast.

    You have to spend money on these units annually. You have to decalcify those units with a pump and the mixture. That's X amount of dollars for that pump, then X amount of dollars for the chemicals to clean what you cannot see, just gauge by the color of the water mixture. 45 minutes or somewhere around there.

    Given that the majority don't ever drain their water heaters once a year...now you're going to spend this much time on your tanklesss...or are you going to run it till it breaks?


    I already know this answer from the 1000's of homes I've worked, and nature of this profession of plumbing and people use their plumbing till it breaks. Having a select few rogue opinions come at me because they take care of their plumbing like they do their hair won't match up in the cards of reality and what all plumbers see on a daily basis.


    I wish people would take better care of their plumbing but it's always profitable for me that they don't. These tankless heaters, when they become popular in the next 10-15 years will be cash cows for plumbers for a multitude of reasons...starting with the #1 buying choice that most property owners are so guilty of:


    Purchasing by price instead of quality

    Example? Buying tankless heaters at big box stores, online, bought through recommendation because a buddy has one and his works well.


    I applaud your good deal, but I will be charging for standing in front of your outdated product from the word go and I will charge for every minute I have to spend on the phone in your home at my shop in my truck or before I go to sleep to figure out what part fixes the puzzle.

    That's only fair because I didn't buy your magic box that makes hot water, you did.
    Last edited by Dunbar Plumbing; 11-14-2009 at 10:03 PM.
    Read what the end of this sentence means.

  11. #11
    Illinois Licensed Plumber SewerRatz's Avatar
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    One benefit you do not see brought up much about a tankless water heater is when it does break/leak it is reparable. If a tank heater leaks you have to drop $600+ on a new tank each time. Where as a tankless water heater is very expensive on the first time install, it is repairable. If the heat exchanger leaks or is damaged due to not maintaining it, it can be replaced. The avg cost of a heat exchanger is around $200 give or take a few bucks depending on model and brand.

    So my point is once you spend the money on a properly sized tankless water heater system, it will not cost you that much every time it breaks down. All the parts inside are easily replaced by an authorized service technician.

    Now will you see a huge savings in your utility bill using a tankless system? No, you will not, unless you do not change your habits of taking showers. Restaurants and hotels will see a huge savings using a tankless water heater system, since they only use hot water a few times a day for peak demand. I know of a couple restaurants that has seen over $750 a month savings in their gas usage once they switched to a tankless water heater system.

  12. #12
    Moderator & Master Plumber hj's Avatar
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    quote; We live in an earthquake zone not to mention we have a few Mountains that like to blow and now a dam that might burst.

    In that case, I would not bother buying a "lifetime" water heater. Sort of like the caveman in B.C. that bought a bunch of "lifetime" stamps and saw a prophet's prediction that "the world was going to end tomorrow".

  13. #13
    Plumber Cass's Avatar
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    Quote Originally Posted by SewerRatz View Post
    One benefit you do not see brought up much about a tankless water heater is when it does break/leak it is reparable. If a tank heater leaks you have to drop $600+ on a new tank each time. Where as a tankless water heater is very expensive on the first time install, it is repairable. If the heat exchanger leaks or is damaged due to not maintaining it, it can be replaced. The avg cost of a heat exchanger is around $200 give or take a few bucks depending on model and brand.

    So my point is once you spend the money on a properly sized tankless water heater system, it will not cost you that much every time it breaks down. All the parts inside are easily replaced by an authorized service technician.

    Now will you see a huge savings in your utility bill using a tankless system? No, you will not, unless you do not change your habits of taking showers. Restaurants and hotels will see a huge savings using a tankless water heater system, since they only use hot water a few times a day for peak demand. I know of a couple restaurants that has seen over $750 a month savings in their gas usage once they switched to a tankless water heater system.
    How much is the labor cost to swap out the exchanger....

  14. #14
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    Intereting opinions. I'll make sure not to call Dunbar for repairs - sounds like he's already charging me just for writing this! LOL j/k!

    I wish I would even have the time to spend an hour in the shower... boy that would be nice. I can't forsee any major changes in shower usage at this point. Probably will remain about equal...

  15. #15
    In the trades Dana's Avatar
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    Quote Originally Posted by D'Brie View Post
    I live here in NW Washington too and I like to be prepared. Having a 50 gallon tank of water can be a good thing. No power = no problem but a tankless water heater can use less energy too.
    With a cheapo Bosch 1600H tankless, no power, no problem and an endless dribble of hot water (1 shower, not 2.) No standing pilot, no standby loss, EF=0.80. Takes no space, needs no special venting. Fill the hot tub? No problem (unless you're in some wicked hurry.) Eight sweaty hikers all want to take a shower? Go ahead (but either share the shower or go one after another, eh? ;-) )

    I lived with a similar-sized dumber'n a box o' rocks type of tankless in coldwater New England (retired it fully working after 15 years of service)- not too painful to deal with once you get over the idea of keeping the hot water taps on at the tiniest trickle. (With a min-mod of ~30KBTU/H it really wants to be 1.5gpm or more.) If you can tolerate waiting until the ol' lady is done with the ( 2.5-3gpm ) shower before running other taps at full bore you can pretty much live with one o' those, and it's not dramatically more expensive than a pretty-good big tank.

    Of course now that I have one of those bigger-deal tankless units (installed as a hydronic boiler) with all of the sophisticated electronic controls bla-blah to boost efficiency a whopping few percent I'll be counting on the mass of the indirect/buffer tank to coast through power outages with a bit of hot water. Running it as a combi it gets better efficiency than either a standalone tank or a standalone tankless. It never short cycles on a hand-washing draw OR a heating zone call. In summer it trades the (very small) standby loss of a well-insulated buffer tank and plumbing in exchange for a much-improved average combustion efficiency. With no gaps in the tank insulation or a center flue HX to convect heat away the indirect/buffer has much lower standby loss than a standard standalone tank.

    I coulda done the same thing with a cast iron boiler, but the standby losses would be higher, the peak output lower, and it wouldn't modulate with load, resulting in a lower heating AFUE. For a lot more money I might have used a mod-con boiler and saved myself 75-100 therms/year (maybe), but there I'd have either had to oversize it (or the indirect) to handle the peak DHW load, or oversized it for the heating load, giving up in cycling losses some of the condensing efficiency gains. By no means is the tankless as efficient as a mod-con, but it would take quite awhile to make up the price difference in fuel savings. It's cheaper at least as efficient as a low-80s cast iron boiler, with a lot more system design flexibility. It's a middle path, and not necessarily a terrible one (TBD- we'll see after it's been in service for a decade. ;-) )

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