We have a water heater and it leaks water though the relief valve. But, it only happens when the water heater is warm. If the temp is turned down (a.k.a. Off) the relief valve stops leaking. What's causing that ? Then someone volunteered that a few years ago a plumber was there and replaced the guts of that relief valve. Leak: Its a little more than a constant trickle, does not appear to an issue with the expansion tank or water hammer effect.
Any idea what is causing this behavior ? Thanks
Yes, heated water expands and increases pressure. You have two choices to fix it. Replace the valve with a new one or repeal the laws of physics.
Yes, could be full of water
or add an expansion tank. They make small ones about the size of a basket ball that can deal with the amount of expansion you get in a water heater. If you aren't a plumber, you could get a "Y" adapter, a
3/4 NPT to hose adapter and hook it up where the washing machine connects with a washing machine hose..
Or bypass the "backflow preventor" valve between your home and the municipal water supply and just let the exapanded water, so to speak, push back into the water mains.
Oh wait. That's _VERY_ frowned on...
This wasn't a problem before backflow preventers were a thing. . I have a well so we have built in expansion protection in the well tank. That is why people have expansion tanks on city water tho. Maybe the house originally didn't have backflow protection and it was added later, causing this problem.
That's actually my likeliest suggestion as to what happened.
And it was quite possibly added without the OP knowing..
Assuming the system has one, most around here do not.
Could just be a bad valve. Should be trivial, unless it's an old tank and it's rusted in, something bad happens when you try to get it out.
Not only that, but that valve is not ONLY a pressure valve - it has a thermal component as well. Generally they are calibrated to release at 210F or 150PSI (that is why they are called T&P relief valves)
except when the house never had one. Never had one in any house I've lived in or owned.
Me either except maybe the rental I lived in on Sanibel for a year. I never had reason to look.
Home is 15 years old, so Yes it has an expansion tank and a chk valve to city water. (house has sprinkler system) The expansion tank has been replaced, but the relief on the hot-water-tank still leaks when the heat is turned up on the tank (natural gas).
Looks like replacing the valve will require removing the whole valve assembly. Is there any way to just replace the guts of it ? (spring + washer) Can you buy a kit for that ? If I stick a pipe-wrench on that valve and something else breaks, I could end up replacing the whole tank ?! Right ?
Yup, the joys of home ownership. Bob is right, they are usually a non issue to replace. While you have the water pressure drained down it might be worth checking the precharge pressure on the expansion tank. If this is not a bladder tank, just an inverted cylinder, simply draining the system (open a faucet up high and down low) and letting air back in might fix it, like "recharging" your water hammer arrestors.
Replacing the whole thing is the surest way, I wouldn't screw around trying to replace parts, even if they were available. It should come out without creating any new problems. There is always some small chance, but you have to do what you have to do and even if it winds up screwed up, if that tank is 15 years old, it's at or past it's typical life already. If you want to be paranoid, you could have contingency plans for where to get a replacement tank, etc just in case. Last one I did I bought it at HD and used one of their rental trucks to get it home.
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