I've got a 40 gallon water heater, and what I've been finding is that it provides just enough hot water to fill my sizable bathtub, but no more. Which means if I want to rinse off with the shower after the bath is over, that rinse is going to be ice cold.

I started looking into buying larger water heaters, but found an article online that said there was cheaper alternative involving the following two steps:

  1. Install a tempering valve, and
  2. Crank the heat way up.

By turning the heat way up, but then subsequently tempering it with cold water, this will turn scalding water back into hot water, and the net result is that you'll be able to pull less water from the water heater to get the same result.

That does sound like a good alternative to me, but I have some concerns. Would cranking the heat way up actually cause any damage to the water heater? Or limit its life perhaps? Thanks for any advice you can provide.

1 Answer 1


The usual remarks about the safety of scalding water anywhere in your system go here.

Physics says the life of your tank will decrease, but not enough for you to notice.

Everything else being equal, hot water has a slightly higher pressure, but expansion tanks are there to deal with that very problem.

The one place you might notice a difference is in energy use. Water in the heater will cool faster when it is hotter. But as worst the difference will be a few dollars a month.

If you are going to pay someone to put in the tempering valve, then it is likely worth changing the tank at the same time. A bigger tank is the right answer in the long run. The efficiency of the new tank will be higher. The water will last even longer with a bigger heater and tempering valve. I guess it depends on how long you think your current heater will last.

If you sweat your own pipes, I would say stay with your current heater until it is old enough to replace.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.