We are replacing our 16 year old hot water heater that has not be running the last day or so. The plumber tested the water pressure of the tank at 90 PSI. He said that is too high. We had a PRV valve installed a couple of years ago where the water comes into the house. The plumber is saying that it must be bad and it will need to be replaced with the water heater or it voids the warranty. Is this true?

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    Depends if the plumber is scamming you or not - if the PRV is adjustable, can it be adjusted? Do you have a pressure gauge in place, what does that show? If you don't have a pressure gauge in place, why the heck not? - Without one, you have no idea at any time if the thing works or not... Certainly could be the case that it has failed (if only a couple of years old, was there a warranty on it? Why did it fail, if it failed? Perhaps it needs something like a filter rated for the full supply pressure ahead of it to protect it from junk in the water supply?) Test with your own gauge for a start.
    – Ecnerwal
    May 3, 2020 at 16:08
  • I agree the PRV should be set no higher than 80 if it is not working it would be a good time to replace it. Normally turning the adjustment CCW counter clockwise will reduce the pressure.
    – Ed Beal
    May 3, 2020 at 16:29
  • I had a plumber lie to me about the PRV failing and reported an excessive pressure level. I tested the water pressure and it was normal (60 PSI). I think there are a few unethical actors out there trying to jack up their bids so that they can install new, spendy PRV's. As Reagan once said: "Trust but verify".
    – Buck Khoe
    Apr 5, 2021 at 20:54

1 Answer 1


Normal household water pressure is about 40 to 50 PSI. A water heater pressure relief valve is normally set to to open at 150 PSI so 90 PSI voiding a warranty seems like a stretch. If in fact your pressure is at 90 PSI I'd be concerned about your faucets and appliances valves, ice makers, etc.. because 90 is too high. I'd ask him to check it again and watch him do it (so you'll know how to do it in the future, LOL) if it's high, you might want him to do it. If you have him do it, think about also having him replace your main shut off as those almost always go bad and they're usually right next to the PRV. Good luck and stay safe out there.

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