My water heater sings to me but it brings no joy.

I have a 4 year old Rheem gas water heater. This week the thing has started "singing." Intermittantly, but often enough to be really annoying, it emits a high pitched tone. I've caught it in the act and the sound seems to be coming from something labeled an "expansion valve." It connects at the cold water input just below the cut off valve and it has an overflow pipe that runs into my sump crock. I opened and closed the valves (PRV as well as the cold water in valve) thinking that might shake loose some lime or something. The noise went away for a day, but now it's back with a vengence. As well, there seems to be a small amount of water coming out of the overflow pipe and into my sump.

Is this thing something I can adjust or do I need a new expansion valve?

Thanks in advance -- this is my first post so be gentle with me!
-Tic

The valve you are talking about (assuming I'm correct) could be failing. It is designed to open if either the temperature gets too high, or th epressure exceeds the design parameters. The spring in the thing sometimes wears out and releases pressure before it was designed, but you could actually have a problem with high pressure, too. Some water systems have a one-way valve - water comes into the house, but cannot go back out. The cold water in teh heater expands when it gets heated, and could be causing the pressure to exceed the safety setting on the valve. These one-way valves are sometimes in or near the water meter or if you have a pressure reduction valve, it typically has one in it. If your system has an expansion tank (the only way to reliably keep the system from venting like yours), then it could have failed or the pressure has leaked out of it. If you have an expansion tank, knock on it and see if it sounds hollow on one end. If it doesn, then it is probably okay. If it doesn't, then turn off the main water valve, open a faucet until the water stops (your're relieving the ressure in the system), then take a tire pressure gauge and check the pressure in the tank. If it is zero, try to pump it up to (maybe 40# or so?). If it holds, shut the faucet, and turn the main valve on, and you may be okay. If not, then you may need a new tank. Note, I'm not a pro.

Jim nailed it. I had the same problem and a water expansion tank fixed it.

One way to check on this theory is, the next time you hear "singing," open a faucet anywhere in your house. If the "singing" stops immediately, this suggests that you are experiencing the problem Jim mentions.

40 gallons of water which is then heated to 120 degrees can expand as much as 0.5 gal. and that extra volume has to go somewhere...

Thanks!

Thanks, guys. Sounds like either way, I need to replace the valve.

Is it necessary or recommended to replace the simple valve with a pressure tank system? I've never had a water heater with pressure tank -- do I need to check the pressure very often? Is it tough to install (I'm reasonably competent, but a lot better with electricity than with plumbing!)? And how do you pump the thing up in the first place?

Thansk again!
-Tic

WHoa...the pressure tank does not go in place of the valve, it is in addition to the valve. Your T&P valve may be worn out, but if you have a closed system (either from a check valve or in an pressure reduction valve), then you should have an expansion tank in the system. Your T&P valve might be perfectly fine.

An expansion tank can go anywhere in the supply system that is convenient. A brass threaded T, a shutoff valve (so that you can replace the tank easiy), and screw the thing in and it's done. My unprofessional opinion.