Water Heaters - Gushing Pressure Release Valve!

I've recently ben having a problem with my pressure release valve on my seven year old Bradford White water heater.

It started as a small drip after turning up the water heater. (hotter) I thought the pressure release valve might have some corrosion so I opened it fully a few times to flush it out. It seemed to help the problem at first but it kept getting worse. Soon, I noticed that after a shower or load of laundry that it would start gushing water. I tried turning the water temperature back down, and this helped at first, but now it has started gushing again. :alarm:

What should I replace? Is this an overheating water heater, a bad pressure release valve, too high water mains, or something else. I'd hate to call a plumber if all I need to do is replace the valve.

Thanks!
Joshua

Joshua: welcome to the forums! You've got to correct this today. First, the T&P valve may be faulty, and changing it may take care of the problem. If it is working properly, then you have either too high pressure or too high temperature. You should check your inbound pressure with a gauge attached to a faucet and let us know if it is more than 65 psi or so. Reduce the heat to midrange. Anything hotter will scald children. But before you go changing stuff on this old heater, you may want to consider replacing it. But do all this asap. You don't want a faulty heater to damage your house or people in it.

Could be just a defective TPRV - frequently, once operated, an older TPRV will never again seat properly.

That said, yes, you want to get it looked at immediately.

Rising water pressure after a use of hot water is indicative of a "closed" water system. This is often the result of the water utility changing out older water meters for new models that do not allow "backflow" from the house back to the municipal system.

It is also a problem when the house has a pressure reducing valve (PRV) on the incoming water service to reduce high municipal water pressure to a safe pressure for the house.

In either case the cure is the addition of an expansion tank on the cold water supply to the water heater.


As for the T&P valve...I suggest that you change it and then test it every six months by pulling the handle to the full open position, letting it flush for a second or two and then releasing the handle.

Joshua: welcome to the forums! You've got to correct this today. First, the T&P valve may be faulty, and changing it may take care of the problem. If it is working properly, then you have either too high pressure or too high temperature. You should check your inbound pressure with a gauge attached to a faucet and let us know if it is more than 65 psi or so. Reduce the heat to midrange. Anything hotter will scald children. But before you go changing stuff on this old heater, you may want to consider replacing it. But do all this asap. You don't want a faulty heater to damage your house or people in it.

I tested the water pressure and it's 79 psi at the water heater drain valve and 85 psi at an outside faucet. Should I replace the T&P valve and add a pressure reducing valve? It sounds like I also might want to add an expansion tank.
If I do add a pressure reducing valve, where should I put it? On the incoming line to the water heater or where the mains enter the house?

Thanks for all your help,
Joshua

If you don't have an existing PRV, I would install one just as the water enters the house, so all the system will be at the same pressure. I would opt for about 65 psi, although a variance is normal. Approaching 100 psi is not happy. Once you are able to regulate the pressure, and install a new T&P, things should settle down for you.