Profile picture for Peter Leeds

Tankless water heaters: Pros and cons?

One feature of a green home is a tankless water heater.  Various consumer reports seem to slam this innovation as being not only not worth the money, but not even really that significant of an environmental benefit.  What has been your experience?
  • July 30 2011 - Windham
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Answers (14)

Best Answer

Profile picture for Michael Helton
Tankless are pretty darn sweet and everyone who I know who installed one is very happy, but it really comes down to cost and the needs of the house.  It rarely makes sense for rentals.

I did a bit of research on tankless and what it came down to for me was it made no sense (enviromentally or from a cost-savings perspective) to replace the water heater when it was still running.  I did not want to add to the landfill.  However, when the water heater went out and if I was going to be in the home for 5 years then it definitely made sense.

The major cost for install is in the plumbing, so if you are a plumber or know one who will cut you a break the overall price is drastically reduced.

Additionally, some states and/or public utilities offer some very nice rebates for installing these.

One final thing qualitative feature is how many people use the hot water and when.  If you have one person in a house then a normal 10 gallon water heater works fine, but if you have 4 teenage girls you might runout of water regularly and an infinite supply of hot water could be worth every penny!
  • July 30 2011
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Profile picture for JenniferClayton6
Love my tankless!
  • January 20
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Profile picture for RemaxBetty
Another great use for a tankless is if you have a bathroom at the far end of a home,...and it takes a long time for the hot water to heat up...this really helps speed up the process. ( less water used too.)

The tankless is initially more expensive, but long term I think it would pay for itself.

B
  • August 31 2012
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Profile picture for user491482
[Promotion removed by Zillow moderator. Please see our Good Neighbor Policy for more information.]
  • August 31 2012
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I think Pasadenan has this right and what I would like to change is #1.
I could even see replacing #1 with Customer satisfaction. 
Sense most people are using reason #1 the most, they should be aware that most Green Building and Energy Efficiency experts would NOT choose tankless anything. It might be a small majority but it is growing every day.
  • September 13 2011
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Profile picture for Blue Nile
4 major reasons listed for people choosing natural gas tankless water heaters:

1) individuals or families dedicated to energy efficiency and green building
2) users that require endless hot water for large families or luxury bath fixtures.
3) those who need these water heaters for physical space savings
4) for use in a summer or part-time home.
  • September 13 2011
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Profile picture for Blue Nile
One thing often not considered... If the water supply is cut off due to a disaster; some people rely on the water stored in their water heater tank and the water stored in the toilet tanks.

You get rid of these tanks, and you have no "back up" water supply, unless you are manually transferring it to 1 gallon, 3 gallon or 5 gallon containers.  And then you have to be concerned about purity if you are not changing the water frequently.

A 30 gallon or 50 gallon tank should get most household through any 3 day "outage" from an earthquake or other infrastructure problem.  (Yes, you have to learn how to get water out of the tank with no water pressure and no air intake, but it really is quite simple once on looks into it).

Also, it is nice to have gas heating in the home, as it gives you an alternate energy source if the electricity is shut off due to infrastructure problems.  Gas goes out?  Use electricity.  Electricity goes out?  Use gas.  Of course, both may go out, but then there is always the car...  And most of the energy usage by Americans is "wants" rather than "needs".
  • September 13 2011
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They really do have high customer satisfaction, but the most recent, well respected scientific study finds them to be not cost effective.

Minnesota study questioning cost effectiveness of gas tankless water heaters.

Concluding sentence from the study: "Even with these positives 
of tankless water heaters the low cost of natural gas and the high installed cost of TWHs limits their feasibility.  Without considerable rebates the simple paybacks for these heaters were 20 to 40 years, making widespread installations seem unlikely.

Other problems I like to point out: Existing homes often need new infrastructure, Most dont work with low flow fixtures, Cold water sandwiches, lose supply during power outages, dont work well as solar backup, possible longer lag time, dependence on a non-renewable resource, a possible increase in overall energy use due to endless supply. 

Electric Tankless are out. Unless they are for one, lone fixture..Forget it. Gas/Propane tankless are the only tankless to consider for whole house use.
Green is in the eye of the beholder but we take the approach of an all electric home, which has the safest indoor air quality and opens the door for renewable energy production.

Heat Pump Water Heaters are the future of water heating. They are already one of the most efficient options available and they work great as replacements because they dont require a change in infrastructure. 
  • September 12 2011
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Profile picture for Michael Helton
SoCal, good point.  It is not infinite.

@mborman:most people do not know that you are supposed to flush a normal water heater once a month.  You might be horrified if you saw what was sitting in the bottom of your water heater after a couple years.
  • August 04 2011
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Overall they are nice.  Because most I have seem are located on the exterior of the home and have little insulation you will find that the valves will freeze in below freezing weather easily if you do not use it during the night.
  • August 04 2011
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Profile picture for mborman
like it!  pretty awesome.  never run out of hot water.  Only thing - be prepared to service about 1/year to flush the heat exchanger to avoid hardness build up.  But we LOVE it.  
  • August 04 2011
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Profile picture for SoCal Engr
@ Mike...

The "infinite supply of hot water" is the part of the marketing that can be misleading. You have to look at the GPM and "rise" info.  The max GPM is typically constrained in how much it can raise the water temperature, so you really need to have some spare capacity. And, that costs $$$.
  • July 30 2011
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Personal experience. Prefer tankless
  • July 30 2011
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Profile picture for SoCal Engr
I looked into a tankless water heater, but the main issue is cost. As with many 'green technologies", the startup costs is often more of an issue than the technology itself.

Additionally, there are decisions that have to be made between gas-fired and electric, as well as capacity. My research also indicated that, depending on the size of the house and hot water demand, there may even be a need for multiple units (i.e., additional cost).

As for "envrionmental benefit", that's really mostly a buzzword. In some applications, the tankless unit will save some $$$ (which means either less electricity or gas). However, we were able to achieve a reasonable balance between supply/cost by managing the recirculator built into our hot water system.
  • July 30 2011
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