Re: Leaking temp/pressure valve on hot water tank
Posted by John Scates on February 12, 19101 at 16:46:05:
In response to Re: Leaking temp/pressure valve on hot water tank
Dennis:

Your presumption is correct, that the pressure should equalize with the public system - EXCEPT that some communities are now requiring that a check valve be installed on the water supply line to the hose to prevent backflow into the community system. Thus, the pressure builds up every time the heater runs its cycle if no faucet is opened. The relief valve is working correctly.

Solutions: a device called an "expansion tank" is sold to absorb the expanding water as it is heated. In your situation, this may be a good idea - your whole plumbing system is being repeatedly cycled from 75 to 150 psi with each heat cycle. Eventually this may take its toll, rupturing a hose underneath a sink, toilet, icemaker, water filter or the like. The in-the-wall piping usually holds up well, but I see a lot of ruptured hoses and I am beginning to suspect that this pressure cycle is one of the causes.

- John Scates


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