I have recently bought a new house the seller had a plumber put in a new 40 gallon hot water tank with an old expansion tank so we had problems with the releif vavle popping off,, so we checked the inlet water pressure it was registered 142 so installed a pressure reducer valve it was factory preset to 55, we installed a new expansion tank and set it to 55 we are still experiencing high back up pressure up to 125, when the water is used it drops to 55, what could still be the problem the releif valve is still weeping?

defective PRV?



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After the install the pressure would not read 60 or 55 psi. But keep thinking...

Yes I am still thinking,,, that after the heating cycle the backflow pressure is hitting the pressure reducer valve causing pressure to0 rise to now 120 what do I do with the extra pressure, 40 gal tank with a 5 gal expansion tank,,, what else is there?

Shut the heater off, run the water, then turn it off. What's the pressure? Does it stay at 55 psi?

Your residential water pressure should never be over 80 psi if your home is on a street level lot. Does your gauge read other than 55 psi? Perhaps it is not functioning as it should.

Also the Expansion Tank air pressure should be 10 PSI greater than the 55 psi house water pressure. This gives the water a place to expand in your system as your water heater heats up to normal temperature. My water meter at the street has a check valve causing my system to be closed. Your meter may have a check valve also dictating the need for the expansion tank. Make sure your expansion tank is sized correctly also. Good luck



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If the PRV will maintain a "running" pressure of 55 psi, it is set for a "static" pressure of way over that.