Loud vibration using hot water

Question

Cast iron sink with wall mounted faucet. The house is 75 years old, the plumbing may be that old too. The pipes are galvanized. The faucet has no identifying marks. There has been no trouble or changes in the plumbing until this started about 3 weeks ago.

When I turn on the hot water faucet about 1/4 turn, a medium flow for doing dishes, there is a loud groaning sound and vibration. If I open the faucet more about 1/2 turn, a high flow for filling a pot, the vibration and sound goes away. I can turn the water on just a little bit to allow a tiny drip without any sound or vibration.

Is this water hammer? Can water hammer just start happening one day and can it occur when a faucet is partially opened and then stop when the faucet is open all the way?

What could be causing this and how can I stop this vibration and groaning?

Answer 1

The faucet washer is loose or worn out. The rush of water causes it to flip back and forth, causing the hammering. Close the water shutoff valves for the faucet, take off the handle and replace the washer (you may have to bring it to a hardware store to get the exact right one).

Answer 2

This sounds like water hammer, possibly caused by trapped air in the pipe. If you have a tank hot water system (i.e. not a combi boiler) then you might be able to fix it by running cold water back through the hot system to clear the air. This is easiest if you have a mixer tap, just cover then end and turn on both taps - otherwise you'll need to secure a hose between the hot and cold taps.

Answer 3

I saw this issue in my old house when the shut-off valve was open only part way. I assumed as it heated up and expanded, the valve started to close. then open, then close. (hammer). Opening the valve all the way fixed the issue.