Our water heater (bought in 2007 so still fairly new still under warranty luckily) seems to release water from the pressure release valve quite frequently. Everyone seems to say that it shouldn't do it often and ours probably does it a couple times per day. 2 main questions - 1. Is there really a risk of too much pressure building up and the water heater exploding (that's what the sales guy at Lowe's said) and 2. Any idea what the problem might be/what we should check out?
The valve is called a TP valve. It stands for Temperature and Pressure relief valve. If either the temp or pressure goes over the set amount, the valve opens and releases water. This is a safety feature to prevent the unit from exploding. You may have the temperature set too high on the heater. The valve may be bad and can be replaced for under $15 and 15 minutes work. The valve operates with a spring and sometimes it can fail. On the valve is a plate that tells how much pressure and temperature is needed to operate it.
Theres no risk of the water heater blowing up if the relief valve is doing what is supposed to.But i recommend a professional check out the installation.Do you know if you have an expansion tank installed on the cold water side? We put one in on every water heater installation.A professional will also check system pressure-some houses have a Pressure Reducing Valve (PRV) and they can fail.You need to check static and dynamic pressure both.And finally sometimes relief valves fail too.If you dont know how to check these things,call a professional.
Don't let anyone foul you with this question because you have a bomb in your house and that pressure relief valve is telling you it's building pressure and when it builds enough pressure you will know. Since this is under warranty I would recommend calling a service tech out to look at it. It could be just the valve but generally they only pop off when they build up pressure. If it were just a leak I would say just the valve. Have you checked the temperature setting on the valve. Maybe it got moved up to a Higher setting. Or even better stay and watch the water heater go through a heating cycle. But don't take this lightly.
I doubt that there is any chance of the water heater exploding since the safety valve is leaking. Have you checked the water temperature settings? After no hot water has been used for a while, run some hot water and check the temperature. If it is near boiling, the you need to check the settings. It could be just a faulty relief valve which leaks when the water surges. When there is high water flow that stops suddenly the water pressure will surge for a very short time. Try opening the bath tub faucets fully and then shut them off quickly while some one watched the heater to see if it leaks. I hope this helps.
Two possibilities: When cold water is heated by the water heater it expands. In most houses the tiny bit of extra volume caused by this expansion flows back out the main line toward the street and the water pressure in your home remains constant. Some homes get such high water pressure from the utility that a pressure regulator valve is added where the water main enters the house. But pressure regulators are, by nature, backflow preventers. So now the small increase in volume from heating water results in a large increase in pressure - which is bled off by the Watts valve on your water heater. The only problem is that Watts valves are designed to operate very infrequently and only in an overpressure emergency. Yours is operating multiple times per day and functioning as a pressure control rather than as an emergency release. This can lead to premature fialure and it cn be dangerous. If you have a pressure regulator or a backflow prevention valve on your water main, ten you must have a properly installed expansion tank. The other possibility is that the Watts valve is starting to fail and should be replaced - they normally last the life of the water heater - but you may have gotten a 'bad' one. So, check for a pressure regualtor or backflow preventer and if you have you get a pressure tank, otherwise try just installing a new Watts valve.
