Banging pipes when hot water is on

alonso

I've got rattling pipes, when ever i turn the hot water on the pipes start hammering,banging etc it takes around 10 mins to calm back down, the worst thing is I've had the floor done and new carpet layed so can't afford to lift floorboards up, any advise?

mattogier

It sounds like the pipe (copper) expanding and the resultant creaking is using your (new) floor as a resonating board - is it a particularly long straight run?

a&akay

It's likely to be water hammer. If it's hot water then turn off the tap and it will stop immediately. If it's your central heating then the hammer can be caused by any valve. If you have thermostatic radiator valves (trvs) then go the room where the noise is loudest and turn the trv up or down a bit. The hammer should stop straight away, mine does. If you don't have trvs then try turning the normal radiator valves on or off slightly.

BobProperty

Sounds like water hammer in the cold feed to the hot water header tank could be a possibility. Otherwise, if you have a combi boiler, it's hammer in the cold to boiler / hot out of boiler.
I'm suspicious that it has occurred after the floorboards have been up and suspect that some of the pipes have been loosened or some packing has been lost. The solution is to get the floorboards back up and fix the pipes, there isn't another easy answer.

plumb1_2

Check the water leval in your header tank if you have a gravity system.
Your system my need topping up.

a&akay

BobProperty's reply has triggered a long lost physics memory - sorry! Water hammer is caused I seem to remember by a standing wave operating on a partially opened/closed valve. If you have an indirect system where you have a cold tank feeding your hot water copper cylinder then the time the noise lasts would make sense, ie the time it takes to replenish the hot water you have drawn off. If you have this type of system then push the ball valve down by hand in your cold tank. This will increase the flow. If the noise disappears then you have water hammer from your ball valve. Try turning your house cold water stopcock down, ie more off, if so.

alonso

Thanks for all the advise,

I made a fatal error

The noise has been going on for a while, it's just the water in basin and bath that cause the noise, it's the expansion of the pipes that is causing the problem. I knew about this when I did the floor , I clipped some pipes every meter or so onto the joists thinking that would solve it with no luck.

pjomara

I've a different issue I was hoping someone could diagnose.
Whenever I turn the gas on to heat the water, there's a slight knocking noise coming from the hot press. I can't trace exactly where in the hot press the noise is, but it's definitely isolated to just there.
There's no noise when I turn the gas on for the central heating (independently of heating the water). It's a brand new house and has been there since day one. I bled the rads. After that I'm stuck for ideas.