Vibrating noise in hot water pipe

So here's the problem. This only happens at one sink in the house, nowhere else.

When the hot water at this sink (and only the hot) is turned to about 25% or more there is a loud banging sort of vibration in the pipes (and it makes our dog very unhappy.)

It's a two handle sink with separate H & C lines. When both hot and cold are turned on there is no vibration. Turn the cold off and it's there.

It does not happen when the valve is turned off and it does not happen at less than ~25%. There's generally a delay before it happens of a few seconds.

This only happens at the one sink.

We opened up the wall on the other side of the sink and braced the pipe with a couple of those copper clips, but that didn't help.

We've drained the entire system, twice, hoping it was an air problem, but no joy there either. I turned off the water and then opened all the faucets, top to bottom.

We do have a pressure regulator, but I don't know what it's set for. I can't imagine that it's too high since water doesn't come blasting out of any faucet/valve?

This only started happening in the fall (of '14) so I assume something worked loose?

I think the relevant pipes come up from the floor to the bathroom shower, continue horizontally through the ceiling, and then drop down to the sink. (That drop is where we put the brace.) This in on the lower floor. The upstairs has no such issues. The H line ends there, the C line heads to an exterior faucet.

I'm starting to think that we'll have to open up the ceiling to see what's going on? I sounds like that's where it's coming from.

Thanks for any help you can offer.

The vibration could also be coming from inside the stop valve under the sink for the hot water. Rubber washers, when damaged or loose, can create the noise you hear. Before ripping anything else apart start there. If you have a flexible supply line from the valve to the faucet the same thing could be true for the rubber seal inside the nut of the connector. Next would be to check to see if debris or damage is inside the valve body by removing the handle and stem/cartridge.

Thanks for the quickly reply! I'll check into that and let you know either way.

Caduceus said:

The vibration could also be coming from inside the stop valve under the sink ...

Click to expand...

I think you nailed it.

I pulled the faucet unit, but there was nothing obviously wrong. We replaced the faucet with a new unit and the banging/vibration is gone! Yes!

Thanks for your help!!