I had my 1940's home completely re-plumbed 23 years ago and have had relatively few problems until now. I recently had a failed water pressure regulator/valve replaced, ( I live in the hills and water pressure is very high, so the valve needs replacing every few years). Since then my water pipes are rattling up a storm when I turn on the hot water to my upstairs sink or shower, but not the tub or anywhere else, (other bathroom or kitchen). Is this as simple as a strapping breaking away or could it be much more complicated? Unfortunately there are no access panels for the shower or sink. Yeah, I know I'm going to have to open up some walls. Thanks!

To me that sounds more like a loose washer or something caught in a valve.

Open the sink or shower hot water to create the noise. Feel along the pipe to try to determine where the vibration is the strongest. If there is a valve between the hot water heater and the bath it may at that valve. Otherwise it may be at the cold water input valve to the water heater.

Because you just had PRV valve replace also check there, not logical but check anyway.

Probably the cold water input valve to water heater. Different flow volumes create different vibrations. You could open sink, create noise, then open tub faucet to see if noise changes. If it does that reinforces the idea of a loose washer in cold water input.

Could be a piece of solder inside the pipe from changing PRV, migrated to the water input valve.

Thank you very much hkstroud.

I remembered one other thing. When I turn on the hot water (and the rattling begins) only a fraction of usual amount of water comes through either of the two faucets until I move the handle, (which is now suddenly tight) beyond that point.

What kind of valves, single handle or two. Sink, shower or both? Assume low flow does not occur on cold side.

Quote:

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(which is now suddenly tight)

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Don't know what to make of that except that possibly solder migrated to valves. Turn off water, remove valve stems, turn on water briefly to flush valves.