Drilling sound when hot water is on

adocholiday

Hi all,

I just noticed this evening that I have a very loud drilling sound (best way I can describe it) when a hot water tap is turned on. The strangest thing is that I can't pinpoint where it's coming from.

The hot water cylinder is in a room directly below the tank in the attic. We have a grundfos 3 bar pump for all the hot water and for the bathroom cold water. The 2 bathrooms in the house are either side of the hot water cylinder and the pipes for those bathrooms run across the ceiling so there's not much enclosed pipework other than a single line under the floor to the kitchen. I initially thought it might be the pump but the noise doesn't happen when the pump is running for the cold water. Also turning on the shower which has a mixer doesn't cause the sound. It's only when a hot tap is turned on.

I've checked what I can and there's no obvious location or cause for it. Just wondering what it might be and whether or not I should turn off the hot water? Hoping it might be something simple that won't need a plumber to call out.

Worth noting that the cylinder is relatively new, we renovated the bathrooms about 4 years ago and upgraded it at the time.

machiavellianme

Sounds like water hammer. You've a loose pipe somewhere that vibrates. Very difficult to pinpoint and resolve.