Leak from hot water heater

RV'S have a closed system, as the water heats it has to expand somewhere so out the relief valve it goes, you need to establish an air pocket at the top of the water heater for water to expand to, shut water heater off, shut incoming water off, open inside faucet and them open relief valve until water stops draining, shut relief valve then turn water on, then faucet off, the water heater does not draw the hot water off the top therefore leaves an air pocket in place, every once in awhile you need to replenish the air pocket....

As mentioned never put a plug into the p/t valve

You can find them at hardware stores but there are 2 sizes. 1/2 inch and 3/4. Measure the diameter of the thread that screw into the tank to be sure.

I speak from experience, it's a pain to buy adapters to make the wrong one fit, but you can.

Thanks again for the information. I will try to release the pressure/clean the dirt out of the area by the methods described before replacing the part.

I question Home Depot will have a replacement. As I recall, the typical home water heater uses 3/4" male pipe threads on the relief valve. I think the RV water heaters use 1/2" Male pipe threads. Be sure to check this, I could be wrong.

Wayne

Just give the handle a quick pull or two . Wear gloves it's scalding hot water. That should clear the built up crud and cure the drip!

could be that you just have some mineral build up in the valve. try to flip open and closed a few times and let the water spray out along with the mineral, if that doesn't work, THEN replace the valve. there is very little maintenance with these valves, normally they will last not for ever but for a long time.

What the others have said try and reestablish the air pocket and when you open and close the relief leveler let it snap closed do this a few times.

Before you replace the leaking valve get some PB BLASTER and after relieving pressure on the tank open the valve using the lever. Spray into the valve opening while opening and closing the lever. Let sit for 24 hours or longer. Pressurize valve and see if the leak has stopped.
I have done this on a hot water heater valve and it worked for me.

See the label of can

I'm surprised that no one has mentioned this:

The pressure relief valve can also leak when the airspace in the tank is gone. There should be air above the valve to allow for expansion when the water is heated. If no airspace then the expanded water is forced out the pressure relief valve.

To ensure a proper air chamber: Shut of water to system (either at the tap if on city water or turn off the pump. Open the pressure relief valve and a hot water tap at a sink. If no water runs out, the air chamber is OK and there is another problem, likely the valve. IF water runs out wait until the water stops running,close valve, turn off hot water tap then turn on the water pump or the city water. This procedure will restore the air in the tank.

Surprised no ones suggested trying to reestablish air gap? That and flushing. Couple of threads in the TCU under appliances.

The pressure/ temperature relief valves do fail or stuff gets lodged on the seat, sometimes opening, letting the handle snap close will seat. Sometimes not. But sometimes, though Ive not experienced, if no air pocket in tank, as water wont compress, pressure can cause valve to weep.
They are generic standard valves but many RVs use 1/2" threaded base, which isn't so common and can be hard to find localy at a hardware store.

EDIT: I type to slow..