Banging when opening/closing faucet...

[hj]

You may not have to change the nipples but, rather, pop the heat traps out of them.

[LLigetfa]

You may not have to change the nipples but, rather, pop the heat traps out of them.

+1

I suspect new ones would make the same noise. Mine have been making that noise from day 1.

It's because now and then tank sediment gets up into them and they get sticky that I'm considering removing them. Laziness has prevented me cuz there are no unions so I would have to cut or unsweat the pipes to get at them.

[spinn]

Was this problem ever resolved? I have the exact same problem that no one can find a solution to. Banging / knocking noise directly behind the bath valve of new install at second floor bath. The noise occurs whenever any faucet in the house is turned on or off or when washer, dishwasher, toilet runs.

The sound is definitely behind the bath valve and it is not pipes banging as I can touch and see the pipes through the rough-in attic space behind the bathroom.

There are shock arrestors on both the hot and cold pipe and I have tried flushing the system in several different ways.

Also, the noise stops when the the supply to the new tankless hot water heater is turned off. THe noise started before the tankless was installed though.

I thought maybe it was a faulty bath valve but since you replaced your cartridges and the noise persisted....I don't know.

Any further suggestions?

[Jcvancouver]

I know it's an old thread but I had the exact same problem as OP and previous poster. I had banging noises coming from behind the bathtub faucets. Any tap turned on or off in the house would cause the banging, hot or cold. I have one handle faucets for the tubs in both bathrooms.

I narrowed the noise down to the bathtub faucets by removing the hardware and closing the feeder screws. Completely closing both feeder screws would eliminated the noises, varying degrees of open would stop the banging for a while but the noises would come back after a bit of use.

I removed the cartridge, disassembled, cleaned, and put it back in (seals and rings seemed fine). The noise Is now gone.

From what I can gather, my cartridge has a metal bearing in it that controls the hot and cold water. This metal bearing that moves left and right and is the source of the banging. The pipes amplified the banging quite a bit and you wouldn't assume the cartridge is the culprit. The way my cartridge works is the metal bearing moves left to cover the hot water opening and moves right to cover the cold. When the bearing is in the middle it mixes and you get warm (obviously). When other taps in the house are turned on and off the effect of water hammer causes this bearing to slam left and right.

By turning off the flow from the HWT, this bearing is constantly being pushed left as there is only pressure from the cold water so it would it would not move back and fourth anymore.

If you can isolate the noise with the feeder screws, it's the cartridge. I have read in other posts that faucets made in different years have different cartridges even though the hardware looks the same. That might explain why OP still encountered the banging after replacing the cartridges. If not, good luck hunting and keep us posted.