Plumbing – How to fix loud foghorn noise from shower when going from hot to cold water

noisepipeplumbingshower

A new housemate likes to end her warm showers with a run of cold water. We've noticed there is a very loud whining/foghorn noise after she switches from hot to cold water, for the duration of running the cold water.
I've read online about banging/pulsating noises when using hot water, but I don't think this situation is the same.

More detail: The housemate switches the shower settings from hot/warm to cold (the coldest setting) instantly, and our shower manages to change temperature with about a one second delay. The noise usually begins after that second's delay (i.e. as soon as the very cold water comes on), and lasts the duration of the cold water usage. It stops as soon as she turns the shower off completely. The noise does not seem to come from the shower head but from the pipes system itself. There is only a temperature knob for the shower, and no power setting.

Can anyone figure out what is going on and I'd be extremely grateful for quick fixes if there are any (aside from making her change her shower habit!). Thank you!

Best Answer

With the flow on the cold being the issue it sounds like water hammer. I have seen extreme water hammer with very tiny flows but it is much more common with high flows.

The 2 solutions I know of for water hammer are. Strapping the pipes that are chattering, if you have access a couple of straps to keep the pipes from chattering will quiet it down. Add a water hammer arrester these are devices you install on the water line that have a chamber spring loaded or air chamber that cushion the flow issue. For best results they need to be on the line that is chattering but I have seen one installed at the toilet fix a shower & sink issue. These devices cost between 10-20$ in the US and since most plumbing is not accessible would be my first thing to try.