New water heater "moaning"

13 years ago

Recently installed an A.O. Smith 50 gal. gas w/h. When the hot water is first run at any faucet or shower in the house, a humming moaning sound, like a fog horn in the distance, comes for a just few seconds, goes away, and then several seconds later a second slightly lower pitch sort of echos the first, then goes away. This only happens rigt when hot is used after not being used for a while. Not super annoying, but concerning that something may be wrong. Hooked up exactly to same existing waterlines and gas lines as the non moaning heater it replaced.

Featured Answer

User

8 years ago

If you have a pressure regulator, that is the first thing to check. If it is not adjusted correctly or is failing it could make those noises. Then check all of your shutoff and supply valves to ensure they are fully open - sometimes they may appear to be open, but may actually be partially closed.

dirtmechanic - The same BS was spouted about Gen X, and Baby Boomers, and, indeed, about the folks we now call The Greatest Generation. Perhaps it's time us older folks learn to accept change without becoming crotchety and mean-spirited about the youth we no longer possess.

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Comments (15)

uniflow
13 years ago
Just a couple of dart throws here. The noise may be expansion creaks from the line growing and rubbing across a structural member as it heats up. The hot water lines must have a little freedom to move or they will groan or snap when they are heated and again when they cool back down.

Also, water contains a certain amount of dissolved gasses(i.e., air). When the water is heated it drives them out in the form of bubbles which are released when you turn on the water. Try turning down the temp. a bit and see what happens.
John Kilpatrick
8 years ago
Did you ever get an answer? My water heater is doing the same thing. And it’s the same brand.
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dirtmechanic
8 years ago
last modified: 8 years ago
It may just be a millennial.

Do you have an expansion tank on your system?
John Kilpatrick
8 years ago
I’m not sure what a millennial is in this context. I don’t think there is an expansion tank.
dirtmechanic
8 years ago
last modified: 8 years ago
Millennial=A new worker who moans a lot. They settle in but it takes a while.

The reason I asked about the tank is that cold water expands when heated, increasing pressure. The description of noise sounds pressure related. A pressure reducing valve or a supply valve not fully open. There are temperature traps on the feeds in and out that can vibrate, some have balls some flappers. Anyway I see now it was a post from 2012 maybe they fixed it.
dirtmechanic
8 years ago
last modified: 8 years ago
Do not virtue signal me. I do not want your opinion. Plus you do not have to hire them and put your money where your mouth is. But I am sure you mean well. Unable to read a joke too, so I suppose I will have to just show you one.
User
8 years ago
"I do not want your opinion," on a public forum - best laugh I've had all day! :>
dirtmechanic
8 years ago
I believe have developed internet skin at some point.
cuddipie
8 years ago
I have this same "moaning" or "fog horn" sound issue and it was installed only 2 months ago. The one that it replaced did not make this noise.
cuddipie
8 years ago
By the way, I also have the AO Smith 50 gal gas water heater and I also have an expansion tank that was added as part of the new installation due to county building codes.
kudzu9
8 years ago
cuddiepie-

If it was installed only 2 months ago, I'd be calling the installer back....
geoffrey_b
8 years ago
Moaning - have you hugged your water heater lately. You know that little door on the bottom, slip some Tylenol's in there.
alzhang74
6 years ago
I just bought a brand new AO smith G6N-UT5040NV water heater from Lowe's and upon installation, the irritating loud noise from burner can be heard throughout the house. AO Smith said it's a recall part that can be repaired, and does not allow return. However, the two repair plumbing companies we called are so overwhelmed with recall service requests, they would not even return calls. We don't know what to do now... Wonder why Lowe's sell a product with recall parts?
norman brown
6 years ago
I had the exact same issue. Lasted for several days, then I shut off the water heater, shut off off the gas supply line and ran the hot water for several minutes from a distant faucet. Then turned on gas, restarted water heater and haven’t had a problem since. Thinking might have been air In water or gas line - thinking gas because I am on third floor and shut off is on ground level. sorry now I gave poor rating. Works like a charm now.