Water Heater Overflow Valve

[Jby0070]

My water heater overflow valve spews water when I turn on the how water switch (gas).

The problem goes away if I shut off the water source and stop heating, and just use tap water. What should I be looking for or replacing?

Thanks,

Jim

[wolfe10]

Jim,

If there is no air cushion at the top of the water heater, when heated, water (being non-compressible) will leak out the overflow valve/pressure relief valve.

Before looking for parts to replace, pull out your water heater's owners manual and read how to reestablish the air cushion in the top of the water heater.

On most: Turn off water pump and disconnect from shore water. Open a faucet to bleed of pressure AND LEAVE IT OPEN and toward HOT. Remove water heater drain plug and drain 1-2 quarts. Reinstall drain plug/anode (depends on brand of water heater-- Atwood nylon plug, Suburban anode). Also, a good time to siphon or flush mineral deposits from the bottom of the water heater.

[vtbigdog]

Brett,

I am guessing the overflow valve the OP is referring to is the relief valve.

I believe for most water heaters you can disconnect the hose and open a hot water faucet and then open the relief valve as opposed to draining the radiator. Let it suck in some air and then close it. Its a lot less messy and also a good way to work the relief valve a few times...which may also be part of his issue...calcium deposits on the relief valve.

[wolfe10]

As Richard said, yes, one can open the pressure relief valve and a faucet to reestablish the air pocket, but many times the mineral deposits on the pressure relief valve seat make resealing tenuous.

Either method reestablishes the air pocket. If it still leaks, THEN it is time to replace the pressure relief valve.