Possible water hammering?? first home buyer

[jeremyj]

Hi there,

I'm about to purchase a home and during the inspection I was informed that when the hot water is turned on in the bathroom sinks, there is a hammering noise until the water is shut off. I researched water hammering and this happens while the water is on and not once it's shut off and it's only in the 2 bathrooms. My inspector said that the water pressure in the house appeared to be normal even though he could not find a water regulator valve.

According to the current home owner, this just started to happen after the bathrooms were remodeled. Does anybody know what is causing this and how I can fix it?

thanks in advance!
Jeremy

[plumber1]

It may not be a water hammer.

There could be a shutoff valve to those bathrooms that has a loose or badly worn washer and the noise shows up when hot water is used in those rooms.

[Mikey]

Did you actually hear the noise yourself? I've got a similar problem in my kitchen, but I know what it is. When the hot water flows in the [new] pipes, there is a more-of-a-tapping-than-hammering sound as the pipe expands and (I think) rubs against the structure it's fastened to. Could be that during the remodel, they fastened the hot-water pipe down or covered it with something so that it creates a similar sound.

[jeremyj]

It may not be a water hammer.

There could be a shutoff valve to those bathrooms that has a loose or badly worn washer and the noise shows up when hot water is used in those rooms.

I'll check that out once I move in.
Thank you very much

[jeremyj]

Did you actually hear the noise yourself? I've got a similar problem in my kitchen, but I know what it is. When the hot water flows in the [new] pipes, there is a more-of-a-tapping-than-hammering sound as the pipe expands and (I think) rubs against the structure it's fastened to. Could be that during the remodel, they fastened the hot-water pipe down or covered it with something so that it creates a similar sound.

Yes I did hear the sound and it was a loud hammering noise only with the hot water. I will do more investigating once I move in to the house.

Thank you

[Mikey]

Reading your initial post again, I noticed you said the hammering stops when the (hot) water is turned off. That's definitely not my thermal-expansion problem, since the creaking noise continues when the water is shut off. I also have CPVC pipes, which may make a difference -- it expands about an inch in 50' for a 50 degree temperature rise; don't know what copper's characteristics are.