Fog Horn Noise

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Bobbylee

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I recently replaced a water heater. The original had no thermal expansion tank and no noise previously. Once the new tank was installed, every time the hot water is used and the water heater turns on the fog horn noise happens. It lasts for about 5-10 seconds and the noise slowly dies down. Would there be a reason why it is happening now?
 
did you add an expansion tank with the new heater?

This is something that creates a fog horn noise.
Could be a coincident that it started with new heater.
Also check you water pressure. That could be a major contributor to problem

https://www.plumbingforums.com/threads/mysterious-humming-noise.988/

Looks like the link to video in my link my not be linked any longer. I'll try and fix it.

try this.
 
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I recently replaced a water heater. The original had no thermal expansion tank and no noise previously. Once the new tank was installed, every time the hot water is used and the water heater turns on the fog horn noise happens. It lasts for about 5-10 seconds and the noise slowly dies down. Would there be a reason why it is happening now?
Is it a gas fired heater?
You may want to try to determine if it is the water flow alone or the unit kicking in without the water flow, so as to narrow it down between water flow or gas flow. If you can manage to do this, of course.

One way would be to shut of heater...flow water. Then shut water and turn on heater.
 
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David, I was going to buy a water pressure gauge to test the psi. The noise is definitely coming from the water heater area and not the toilet.

Diehard, can you go more in depth how gas flow be the cause for this issue? This is a gas water heater. The noise does start when the gas comes on initially.

Thanks
 
I figured we had a couple of potential candidates causing the sound. You seemed pretty sure it was related to the hot water being used and the starting of the water heater. ("every time the hot water is used and the water heater turns on the fog horn noise happens.") So I figured it must have something to do with the hot water flowing or the only other thing that would be flowing, the gas.

I have no experience or reason to believe it would be the gas but only that it was a candidate. Since we know sounds such as these are typically made by passing a liquid or gas through an orifice, and possibly associated with something that's loose which could amplify the sound. So if was happened when the heater started, without water flowing, we could, I believe, eliminate the water as the possible cause. And if the sound was just at start-up doubtful water expansion would be involved.

I suppose there still is the exhaust flow that would be tied in with the firing up of the heater.

So you say, "The noise does start when the gas comes on initially" but didn't mention if that was without the water flowing. ???
 
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So the noise occurs when hot water is used and probably starts after a few minutes when leaving the faucet on. So there is water flowing. This is the only time that I hear it. It does not make this noise while the water heater turns on to maintain the temp.
 
So the noise occurs when hot water is used and probably starts after a few minutes when leaving the faucet on. So there is water flowing. This is the only time that I hear it. It does not make this noise while the water heater turns on to maintain the temp.
Okay, so you are now saying that the noise starts and stops prior to the water heater starting. So I guess that eliminates any relationship to the gas flow and exhaust flow.
But you do feel like the noise is coming from the water heater area?
What type of valves are on the inlet and maybe the outlet of the water heater? Are they fully open?
Must assume you don't have anything special going on. Just cold in and hot out and no recirculation system?
You mentioned you replaced a water heater that didn't have an expansion tank. Does that mean you now do?
And did you need an expansion tank due to having a Pressure Reducing Valve in your water service or something else that would back pressure into the service line?
 
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No the noise starts when the water heater kicks in. I checked the psi and it stays somewhat consistent when I turn on the faucet and when that noise happens.
 
After randomly searching online I found a couple videos that had the exact same issue. It does have to do something with the gas line and it might involve a defective burner possibly. Going to see if I adjust the gas valve and see what happens. If it doesn’t work then I will contact the manufacturer. Appreciate your help Diehard.
 
After randomly searching online I found a couple videos that had the exact same issue. It does have to do something with the gas line and it might involve a defective burner possibly. Going to see if I adjust the gas valve and see what happens. If it doesn’t work then I will contact the manufacturer. Appreciate your help Diehard.
Don't blow yourself up!
Maybe you should contact them first.
 
Did you purge the air from the water lines after you hooked it up?
 
I agree with Diehard. Call the company first. If you tell them you were messing around with the gas valve you night loose your
warranty.
 
Claify
So the noise occurs when hot water is used and probably starts after a few minutes when leaving the faucet on. So there is water flowing. This is the only time that I hear it. It does not make this noise while the water heater turns on to maintain the temp.
You say it's not the burner kicking on that make the noise but when water is flowing.
Some WH have heat traps in the nipples for water supply connection. They used to make them with a floating ball in the cold side and a stainless steel ball on the hot. They tend to rattle.
They replace them thin neoprene discs, with cross cuts, in the nipple. Kind of like a splash guard in a garbage disposal, but much smaller.
It's a long shot, but something to consider.

BUT if it occurs when the burner comes on, did you try looking into the sight glass on the burn chamber . If the burner orifice is defective it can howl, but you should be able to see in sight glass if it's not burning properly
 
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