Re: Water Heater: Pressure release valve
Posted by Dave R. on February 10, 2004 at 17:01:23:
In response to Re: Water Heater: Pressure release valve
Jeanne, I am not a plumber but do have some experience with this problem. First of all, the relief valve leaking indicates that the water heater pressure in the tank is more than desireable and could be potentially very dangerous. I would recommend a plumber check it out unless you are willing to try these things first.

1. Try turning the water temperature down using the thermostat control. You can measure the water temp. with a thermometer at any faucet (it should not be more than 125 degrees F. If the leaking stops, you can try turning the temp. back up gradually and see if the valve holds. By the way, if your water temp. fluctuates according to your thermostat adjustment then your thermostat control is probably ok.

2. If the pressure relief continues to leak, the valve may be bad (some times they get scale or gunk in the valve seat rendering them inoperable). Turn off the water supply, gas or elec. to the tank, follow the mfg. instructions, drain the tank, and then remove the valve. Take it to a hardware store and purchase a replacement (only about $7.00). Install the new valve and restart the tank.

3. If the new valve leaks, then you may have an inheirent condition due to thermal expansion inside of the tank. Essentially, the water heater is building pressure from the combination of incoming water pressure and the rising temp. of the water. If your incoming line has a check valve, then the expanding water has no where to go except out the relief valve. Home Depot sells a Thermal Expansion Tank kit that is placed on the cold water line just before entering the water heater. The Thermal Expansion Tank has a rubber bladder inside that allows the water pressure to back up or equalize in this little tank thereby allowing the pressure relif valve to hold closed.

I just recently installed one of these in my home after experiencing the same problems. The tank and all connecting fittings only cost me(about $50.00). You would have to be capable of cutting and soldering the copper pipe. I installed the tank using two unions so that it could be serviced if necessary. A water pressure gauge is needed to read your water pressure and a bicycle pump is needed to pre-charge the tank bladder to the same pressure as your water pressure. I have not had a drop of water since. Good Luck!

: For 3 days in a row I have had a large amount of water coming out of the preesure release valve on my hot water heater. Does this indicate a problem? Or is the release valve just doing its job well?
: The hot water heater is about 2 years old.

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