Is anybody here a Gas heating engineer?


New Member
Our central heating is banging away like crazy. Knock, knock, knock...and is driving me nuts. It happens when th eheating comes on in the early hours and wakes me up. It sounds like two pipes knocking together and goes on for about two hours, knockinging every second or so.

We called Brit Gas but they say it isnt covered on th epolicy and would cost us £250 +vat to fix assuming it can be fixed I suppose. They reckon it is something they call 'kettleing', however they havent been round to look at all.

Our house is only 8 years old. The problem is only in one room, not throughout the entire house/system. Does the 'diagnosis' of kettleing sound right? Is there a better/cheaper way to fix it?

Any help/suggestions most helpful and appreciated.

P.s I understand that any advice I take here is at my own risk:biggrin:
Have you 'bled' the radiator(s)
Its likely to be the noise created when an expanding pipe creeps over a joist. Best practice is to lay a piece felt in the notch before the pipe is installed. We had the same problem in our bathroom and as a temporary fix I sprayed WD40 into the wood surrounding the pipe. That was five years ago and it hasn't uttered a squeek since.


Taking the biscuit
It does sound like you need to 'bleed' the offending radiator to clear an air lock.
Any good hardware shop will sell you a 'radiator bleed key', and all you need to do is loosen the square stud at the top end of the rad(the opposite end to the temprature control), only a quater to a half turn, you should hear a rush of air followed by some water. When the water appears turn the stud back in quickly to close the radiator.

Depending on how old your heating system is, have a check of all rads, while the heating is running, and make sure the rads are heating up consistantly from the bottom to the top. If any radiator is hot at the bottom and still cool at the top it is likely that the radiator needs to be flushed or unblocked. All good fun!

Hope this is of some help,

T x


we had this with our system,it was trapped air,the banging was aparently caused by the air pockets coming through one after the other according to the plumber,sounded like someone was hitting the floor with a hammer.The system was drainded at its main drain tap,then filled again,and all radiators bled,not had a problem since.When you bleed the radiators,do it with the system off,or air can be pulled back in,and you might have to do it a couple of times,as air works its way round.Hopefully thats all it will be.

Van Nick

New Member
As others have said, it is most probably a sign that the system needs bleeding but if that fails then you may well require a power flush to remove any sludge which may be going round the system, in the radiators or even in the heat exchanger.


New Member
Many thanks all...see i knew it wasn't 'kettleing'!

Its likely to be the noise created when an expanding pipe creeps over a joist.

This sounds like it could well be the problem as the noise does seem to come from low down in the corner of the bedroom, and given it is only a problem in this one room this seems logical to me captain.

Ok so the next question would there an easy way of ascertaining if this is indeed the problem without having to completly demolish and re build my house?
Top Bottom