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Banging pipes close to water heater when flushing any toilet

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Diehard

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Yes, this occurs ONLY when any of the three toilets are filling; as soon as the tank is full the hammering stops. It appears that the PRV is not functioning. I have cranked the adjustment from min to max and the pressure remains at 80 psi with all faucets and valves closed. I also notice that while the toilet is running the pressure is jumping from 40 to 50 psi. Don't think the inoperative PRV would cause this. Still very confused as to why this occurs ONLY when toilets run and not when any other value is opened. It seems that the float valve in the toilets is opening and closing as it runs. I notice that all three toilets do have the identical float valves. Thoughts?
Chances are the pressure won't change if you don't open a faucet to allow the pressure to drop. Let some water out then recheck pressure reading.

If it was only the one toilet, that caused the noise, then I would blame the Fill Valve and suggest you replace it. But I believe it would be too much of a coincidence to have all 3 fill valves go bad.
The next thought would be if the 3 appliances, causing the problem, were fed by a common supply, that was not also feeding other devices. I doubt that is the case also.

Just for the hell of it, turn on the cold water in you bathroom sink while the noise is happening to see if it has an impact on the sound. In other words we're simply increasing the velocity to see if there's an impact.

EDIT: AS far as, "pressure is jumping from 40 to 50 psi.", while toilet is running. If it's while you're getting the noise, it likely the velocity changes/surge pressures. That would stand to reason.
 
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Jeff Handy

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This might be obvious, but have you checked for any loose or wobbly copper pipes that could be clanging against something?

Pipe against pipe, pipe against furnace duct, pipe against conduit or gas pipe, for example?

Sometimes a little piece of cardboard or duct tape at the contact point can keep metal to metal banging noises down.
Or if a long wobbly section is not properly supported, add a pipe hanger or clamp.

Also, sometimes a water pipe is too tightly clamped to framing, and can’t expand or contract along its length easily because it can’t slide inside its clamp as needed.
So it makes annoying noises as the pipes fight the tension building up.
 

GaryAK

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This might be obvious, but have you checked for any loose or wobbly copper pipes that could be clanging against something?

Pipe against pipe, pipe against furnace duct, pipe against conduit or gas pipe, for example?

Sometimes a little piece of cardboard or duct tape at the contact point can keep metal to metal banging noises down.
Or if a long wobbly section is not properly supported, add a pipe hanger or clamp.

Also, sometimes a water pipe is too tightly clamped to framing, and can’t expand or contract along its length easily because it can’t slide inside its clamp as needed.
So it makes annoying noises as the pipes fight the tension building up.
Unfortunately, if this is the case, it would have to be in a wall. None of the exposed pipes where the hammering can be felt are touching anything else.
 

GaryAK

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Chances are the pressure won't change if you don't open a faucet to allow the pressure to drop. Let some water out then recheck pressure reading.

If it was only the one toilet, that caused the noise, then I would blame the Fill Valve and suggest you replace it. But I believe it would be too much of a coincidence to have all 3 fill valves go bad.
The next thought would be if the 3 appliances, causing the problem, were fed by a common supply, that was not also feeding other devices. I doubt that is the case also.

Just for the hell of it, turn on the cold water in you bathroom sink while the noise is happening to see if it has an impact on the sound. In other words we're simply increasing the velocity to see if there's an impact.

EDIT: AS far as, "pressure is jumping from 40 to 50 psi.", while toilet is running. If it's while you're getting the noise, it likely the velocity changes/surge pressures. That would stand to reason.
Yep, question is why does the pressure change while the toilet is running. What ever is causing that is the problem obviously. I guess my next move is to rebuild or replace the PRV since it is the only component proven to not be working properly.
 

Jeff Handy

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This is sometimes frowned upon, but you could try partially closing the shutoff valves that feed each toilet fill valve.

Not so much that it takes forever to refill, or makes a squealing sound from being too restricted.

This might cushion the water hammer a little bit.

This slower refill often keeps your toilet tank from flooding over the overflow inlet, if the fill valve ever sticks and it keeps trying to fill up forever.
 

GaryAK

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This is sometimes frowned upon, but you could try partially closing the shutoff valves that feed each toilet fill valve.

Not so much that it takes forever to refill, or makes a squealing sound from being too restricted.

This might cushion the water hammer a little bit.

This slower refill often keeps your toilet tank from flooding over the overflow inlet, if the fill valve ever sticks and it keeps trying to fill up forever.
Thanks but already tried that (It was suggested by another member). It did not make a difference
 

GaryAK

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Chances are the pressure won't change if you don't open a faucet to allow the pressure to drop. Let some water out then recheck pressure reading.

If it was only the one toilet, that caused the noise, then I would blame the Fill Valve and suggest you replace it. But I believe it would be too much of a coincidence to have all 3 fill valves go bad.
The next thought would be if the 3 appliances, causing the problem, were fed by a common supply, that was not also feeding other devices. I doubt that is the case also.

Just for the hell of it, turn on the cold water in you bathroom sink while the noise is happening to see if it has an impact on the sound. In other words we're simply increasing the velocity to see if there's an impact.

EDIT: AS far as, "pressure is jumping from 40 to 50 psi.", while toilet is running. If it's while you're getting the noise, it likely the velocity changes/surge pressures. That would stand to reason.
Just tried this (opening another valve while toilet is pounding). Had not effect on pounding, however, I learned that I think hammering is the wrong term for what is happening. While the toilet was running and a faucet opened, the noise continued but in listening closely to the noise; the pipes are not moving or banging, the noise is actually just water movement in the pipe which matched the fluctuating gauge bouncing from 25 to 40 psi. The noise is more of a rushing water sound then hammering. I suppose if pipes were loose or against something hammering would result. The noise is loud enough that we hear it in the kitchen which is on the other side of the water heater closet. it cannot be heard throughout the house. Sounds to me like there must still be air trapped in the pipes somewhere that draining and refilling did not fix.
 

Diehard

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Yes, I was thinking it may be a pulsating sound or maybe even a vibrating type noise and not necessarily the sharp banging noise of a worse case water hammer.
In Post #25 you mention, "the PRV since it is the only component proven to not be working properly." The PRV may have something to do with the problem but I don't think its been proven not to be working properly, yet.
Has it?
 

GaryAK

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Yes, I was thinking it may be a pulsating sound or maybe even a vibrating type noise and not necessarily the sharp banging noise of a worse case water hammer.
In Post #25 you mention, "the PRV since it is the only component proven to not be working properly." The PRV may have something to do with the problem but I don't think its been proven not to be working properly, yet.
Has it?[/QUO
Yes, I believe it has been proven not to be working. In post #15 I mentioned that I had cranked the PRV adjustment from min to max and it did not effect the pressure (it remained at 80 psi). I did also open a valve to drop the pressure just to make sure and the pressure returned to the 80 psi even with the PRV valve at its lowest pressure setting (should have been at 50 psi.
 

Diehard

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Okay thanks.
I did not see a confirmation that it was tested properly and could only assume it may not have been.
Just making sure.:D
 

GaryAK

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What type of pipe is used for the main from the street to the house?
Sorry for the delay, in answering, did not get an email. I am not sure about the pipe from the street the house is 20 years old. Not sure what Georgia code was at that time. The only exposed pipe I can see is at the main value and it is only about an inch long under the PRV housing. Looks like 3/4 inch and guessing galvanized. I still fighting this thing. My son just ask a question I had not thought of; are all the toilets on a separate line? Is is possible that their was a code at the time the house was built that required a separate line with a backflow valve?
 

Jeff Handy

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Sounds like the PRV is toasted, water pressure is see-sawing from too high to too low.
Don’t you feel this same kind of pressure changing while showering?
 

GaryAK

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I am still fighting this thing. My son just ask a question I had not thought of; are all the toilets on a separate line? Is is possible that their was a code at the time the house was built that required a separate line with a backflow valve? No way to see the piping without tearing out drywall.
 

Diehard

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I doubt very much if there was ever a code requirement for a separate line for the toilets.
I kind of mention that common line thing briefly in an earlier post but disregarded it since it was very unlikely to have 3 toilets fed by a common line. If they where fed by a common line and had a shutoff valve on that line, then that would be another suspect. As valves, such as globe valves, in particular, have been known to cause that type of noise when the valves washer gets loose.
 

Rickyman

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Change one of the fill valves in a toilet and see if the sound goes away when that toilet is filling.
 

Jeff Handy

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The PRV valve itself is possibly emitting this annoying noise.

Similar to running an old sink faucet at only a weak trickle setting, sometimes the valve starts to screech and moan loudly.

Because the fill valves on his toilets are only putting out a slow stream of water while refilling, that could be triggering the noise in the valve.

There also might be another isolation valve midway somewhere in the house, used to shut off the cold water during repairs to just the upstairs, or just half the house somewhere, for example.

These old valves rarely get used and get forgotten about.

It might even be drywalled over now, or up above a ceiling panel in the basement.
Might need servicing, replacing, or maybe it is partially closed and needs to be fully open.
 

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