We had a new hot water heater installed 1-2 years ago. It worked great up until about 2 weeks ago, where we all noticed that it no longer was heating to the same temperature. I can continue to crank the heat adjustment up, but that makes me nervous that I'll end up burning my children if it suddenly snaps back. What is the best thing to do to start fixing this?

  • Test the heating elements with a voltage meter to see if both are working. I assume it is electric? Probably one element is not working which could be a bad element or a bad thermostat
    – Kris
    Jan 23 '21 at 0:19
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    For a start figure out what type of heater it is, then determine if it's heat-making part or the thermostat that is misbehaving,
    – Jasen
    Jan 23 '21 at 0:19
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    @Kris - Sorry, I meant to put it in there, but it is a gas heater, not electric. I've edited the question.
    – David
    Jan 23 '21 at 1:16
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    Have you tried flushing the heater using the drain valve at the bottom? Also, do you have any other gas appliances? Jan 23 '21 at 1:32
  • Is it cooler on all the faucets?
    – Ed Beal
    Jan 23 '21 at 2:25

It ends up it was not directly the hot water heater. We have a leak in a hot water line that goes down into the foundation of our basement which is even worse. I thought I'd come back and update in case someone sees this in the future. Thank you to all who answered.

  • Ouch - those are expensive. Had a hot water leak in a rental where we paid the utilities once...
    – Ecnerwal
    Jan 30 '21 at 3:10
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    @Encerwal Yeah, the water bill is going to be through the roof next quarter. The quote from a plumber was crazy high too and it was best case without ripping up the concrete ($2700). I just ordered an endoscope to see if I can find where the pipes come up. The bathroom in the basement is only 6 feet from the utility room through two walls. If I can find the other side of the pipe, I should be able to cap the end ends going through the ground and run a new pipe instead. Here's hoping!
    – David
    Jan 30 '21 at 3:18
  • That, combined with the incoming water temperature in the winter: it didn't stand a chance.
    – Mazura
    Jan 30 '21 at 3:24

Flush it using the drain valve. Hard water deposits will settle out on the bottom, and impair the transfer of heat from the flame to the water.

If you are depending on the water heater thermostat to prevent scalding your children, you're not abnormal, but you're doing it wrong.

Use a tempering valve between the water heater and your hot water system. That way you can have the water heater set hot enough to kill unpleasant bacteria, and also have water that does not scald anyone.

  • Thanks for the tip on the hot water. I did just flush it today and got a nice bit of buildup out, but the overall functionality and lukewarmness of the water did not seem to improve.
    – David
    Jan 24 '21 at 6:09

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