Checking for water leaks – want to check the T and P valve of a small under counter water heater by turning it off for a month. need to leave the power on as another item is on the same circuit.
will that damage the heater?
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If you don't get an answer, it may be because your question isn't understood. I didn't get it. Maybe add some detail?
You're going to turn off the cold water feeding the electric water heater, but leave the power on? The heating and cooling of the water (and associated expansion/contraction) may pop the P&T valve, and has some potential to damage the heater. If enough water leaks out to expose the heating element, the element will burn out.
what do you want to see in the test of the T & P valve? a T & P valve should open up and let water out if temperature gets too high, or if pressure gets too high, or both.
if you think it might not be working replace it, but you may destroy a $200 water heater to prove a $12 T & P is OK.
if you think T & P might be bypassing (leaking) water without having had an episode occur where it "should" be bypassing water then again you could try to see if water is collecting somewhere by putting something to catch water at the end of the drain line. if it is leaking pull it open for a sec to let water go through and release, water running may clean sealing surface and it will quit leaking. then again if you mess with it they (plumbers) will come!
Change it (the PT) or leave it alone, but don't turn off the water for a MONTH.
Sorry about the bad question- the outflow if the P T valve goes into a closed drain system in an office wall so you can not tell if it leaks. I was trying to rule out the water heater as a source of excess water use so i wanted to cut off the cold water feed and am hampered as another iten is on the electrical circuit so I can cut not off the electricity for a long time.
T+P valves use to be required to run to a open connection, [i.e. can't be tied solid into a line], somehow things have changed, [depends on area], the whole idea was to see when they were leaking. Your best bet is to cut off the T+P discharge line, add a hose, and see if there are any leaks, lots of luck. ........................................................
"If all else fails, read the directions"
Edited 1/13/2007 1:15 pm ET by Shacko
if you want to shut down just that water heater to see if it changes your water bill go ahead. shut down the power to the circuit that powers the water heater and anything else and disconnect the wires (after you mark which goes where) put electrical twist nuts on bare wire ends and some electrical tape for good measure, put eveything back together and turn power back on.
now this water heater is removed from water and power, completely segregated from system.
> Sorry about the bad question- the outflow if the P T valve goes into a closed drain system in an office wall so you can not tell if it leaks.That's a no-no. The valve must exit into a drain pipe that allows for visually determining if it's leaking, and cannot be plumbed into a sealed drain pipe -- there must be an air gap.
Half of the harm that is done in this world is due to people who want to feel important. They don't mean to do harm but the harm does not interest them. --T.S. Eliot
Just read your clarification. Save time. Either remove the pipe the drain pipe or open up the wall and find out. I wouldnt spend a month waiting to see if a wet spot dried up cause the heater was off. Water in a wall can create alot of problems. Fix it as soon as you can.
If you insist on going your way just disconnect the water heater from the circuit and cap off the hot lines.
I would venture that the PR. valve does not go into closed piping but rather is piped to either directly outside the building or into a basement.
Quite possibly true in SC. I gather that code in the south often requires the valve to be pipeed outdoors, while code in the north prohibits it. (Both for good reasons, BTW.) The OP should check for an exit point for the pipe.
Half of the harm that is done in this world is due to people who want to feel important. They don't mean to do harm but the harm does not interest them. --T.S. Eliot
this is a small under counter heater under a bath room counter in an office condo on a slab- t and p line plastic piped into the wall no pipes outside - have looked many many times.
Easy, turn the temp all the way to hot, come back in an hour or two or better, the next morning--first thing--feel the discharge pipe and if it is hot then you have a leak.
Why can you only check the T&P by shutting of the heat? Seems if it is leaking its more likely to do so under the added pressure of heated water in the tank.
As long as the water heater is in a conditioned space there should be no problem turning it off even with power going to the unit.
He wasn't proposing shutting off the heat, but simply shutting off the water feeding the unit. There IS a problem with doing this: If you shut off the incoming water and leave the power on, heating and cooling in the heater will alternately create high pressure and a vacuum. This is not good for the heater or the plumbing, would likely cause the T&P valve to spit, and could cause the glass lining to crack. Eventually enough water could leak/boil off to expose the a heating element, causing the element to burn out.
Half of the harm that is done in this world is due to people who want to feel important. They don't mean to do harm but the harm does not interest them. --T.S. Eliot
I got that in his latter post. I agree there is a problem with no water but leaving the power on. Thats why I suggested he simply disconnect the power from the unit and cap it off temporarily.
Yeah, he really should fix the drain situation. But if he's gonna have the water off for an extended period he should cut the power to the unit somehow.
Half of the harm that is done in this world is due to people who want to feel important. They don't mean to do harm but the harm does not interest them. --T.S. Eliot
Drain it and turn it off or at least cap the wires to that water heater...
If by chance you power up an electric water heater w/o water the element will toast itself in a matter of minutes.