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pipes making knocking noise

(5 Posts)
mckenzie Tue 14-Dec-10 21:05:03

Please can anyone tell me why the pipes make a knocking noise when the heating/hotwater first comes on in the morning?

It doesn't last for long - maybe about 8-10 knocks. It's enough to wake me up though.


dreamingofsun Tue 14-Dec-10 21:29:25

it might be air in your system. we have a small sort of tap thing thats on the pipe in the airingcupboard. you have to turn it so it adds water to the system and gets rid of air - until the pressure on the gas boiler reaches about 3 i think - it needs doing now as only 1 and making banging noises. don't overfill as i think the plumber said it can explode. are the radiators cold at the top because they've got no water - this is another sign

mckenzie Wed 15-Dec-10 08:38:27

thanks very much dreamingofsun - I'll go take a look at the level. the little tap only goes one way I seem to remember so how do I know whether I am adding or taking water away?

dreamingofsun Wed 15-Dec-10 09:04:06

the dial on your boiler will move up as the water pressure increases. it can happen quite quickly - so one person needs to watch the boiler whilst the other fiddles with the tap. if its like our tap - which only goes one way - it will only add water. hope its the same as ours - difficult to tell without seeing it. just be careful you don't put too much water in - i think this can cause big problems and i've no idea what to do if this happens

Poledra Wed 15-Dec-10 09:06:38

My pipes creak when the hot water comes through them first thing in the morning - it's just the metal expanding as the hot water goes into cold pipes.

Knocking noises can be air in the system though. I refer you to the previous poster's advice on that, as I don't know anything about it (other than how to bleed a radiator that's got cold spots).

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