Water heater making sound

Stan in Oly, WA

Well-known Member
For a few months now, I have been hearing a particular sound from the next room sometimes when I am running hot water in the kitchen sink. The sound is like a cabinet door bumping shut quietly, like it might do if it had been left open just enough that a self closing hinge could not quite shut it until a vibration or an air movement provided an additional push. This sound has been happening for a long time without it registering on me where it was coming from because the gas water heater is located next to the kitchen in a utility room that has large cabinet type doors directly over a small dog door so there is frequent air movement in that room.

I have tried unsuccessfully to track down the exact location of the noise, having my wife turn the hot water on and off while I observed the water heater, but the event is intermittent. I haven't been able to discover a specific pattern to the circumstances yet. I'm reasonably, but not totally, certain that the noise is coming from inside the water heater. There is nothing loose on it or near it that would account for the noise. A few nights ago when my wife was cleaning the bathtub, I could hear the noise every time she would turn on the hot water, but it stopped happening before I was able to coordinate a test with her.

Anybody ever heard of this? I've had a lot of experience with electric water heaters, much less with gas ones. I view unexplained changes in the performance of any piece of equipment with great unease.

Stan
 
It's probably just expansion & contraction the metal gets hot because of the fire heating the water then when the demand of hot water subsides it cools off. Noise will also happen when minerals accumulate it will make snapping sounds and that's nothing to be concerned about. Just the nature of the beast.Just remember to shut off water supply then drain it once every 4 months to get rid of the hard minerals
 
When we had a similar sound emitting from our 40 gal. hot water tank I found I had to drain the dank each spring and each fall. Deposits came out from with in the heater. Noise never came back.
Bob...
 
I've heard what you are talking about.

IMHO, when pressure is quickly lowered in the heater by opening a faucet water that's extra hot (against the element or heat exchanger) quickly expands into a little bubble of steam, making a knocking/cavitation sound.

Just my humble opinion!

(The others have mentioned debris/sediment, which obviously could create a "hot spot".)
 
After a couple years sediment from hard water will fill a water heater causing muffled popping. Flushing solves the problem and will increase efficency. The dinky original drain valve often needs to be removed for a good through flushing.
 
Isn"t that called "water hammer"? Try installing a stub vertical pipe higher than any other. It will contain air, cushioning the blow.
 
Great information and advice, everybody. Thanks. I'm impressed and grateful.

I think all the possibilities that have been mentioned here are reasonable, and entirely possible. However, I lean toward those that would develop over time, since I've had the water heater for years and the noise is relatively recent.

Thanks again,

Stan
 
we drain our tank once a yr to remove crud from bottom of the tank. I did have to install a better water valve on the bottom of the tank. the cheap valve made me nervous when I shut it off. most everytime I had to tighten the packing to solve a drip. I recommend any hot water be drained if you have hard water. ours use to eat up the electic spade that went into the tank.
 

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