About once every 4 to 6 weeks, I notice water in the basement coming from the hot water heater. I'm never present when it happens, I just find water running from the heater to my drain. I do not see any noticable leaks and since this is not a constant problem, I cannot think of where else it could be coming from but the T&P value. The first time it happened, I had taken a long shower after working in the yard. But there seems to be no rhyme or reason to what's causing these other incidents. I use the shower and sinks daily and the clothes washer about twice a week.
What could the cause be? The manual to my hot water heater says: "If the T-P valve weeps or discharges periodically, this may be due to thermal expansion. Your water heater may have a check value installed in the line or a water meter with a check valve. Consult your local sears service center for further info."
I see no type of valve in the line leading to the heater. I tried looking at the water meter, but it's mostly covered in soil. The water supply line coming into this 56 year old house looks fairly new. It also mentions that the T-V value should be operated manually each year. It's been 8 months since I've lived in this house and I haven't done so yet. Would this help to solve the problem?
There's more in the manual for the heater, in bolded letters. "The temperature pressure relief valve is not intended for constant relief of thermal expansion. This is an unacceptable condition and must be corrected."
However, the following website reads: "The relief valve relieves this pressure by discharging sufficient water to bring the pressure down to acceptable levels. If you don't want a pressure relief valve to release this water, you would need to install a thermal expansion tank in the water line to absorb the expansion." (From http://www.keidel.com/mech/heaters.htm
) This website makes it sound like a choice or a preference. The water from the heater doesn't bother me - I can live with periodic draining of water from the heater to the basement's drain. All of the items I store in the basement are nowhere near the heater and are off of the ground anyway. To me, it's no big deal if it's not a safety concern. And installing one of these thermal expansion tanks seems like it would be expensive since most of the supply plumbing in this house is galvanized iron.
The 'handbook' that the home inspector gave me notes that "TPR valves sometime discharge a little bit of water when the tank is heating" This could explain the first occurrance after that long shower. The dicharges I've seen in my house probably exceed a pint and a half of water, but nowhere close to a half gallon.
The water heater looks fairly new. It's a Sears model and when I called them they said nobody would talk to me over the phone and that I would have to schedule a service call. Nice.
What's the next step? Thanks for taking the time to reply.