Knocking pipes.....driving me out of my tiny mind

[Will__]

Knocking pipes

I have a fairly new (a year or two) central heating system. I noticed this first last year but it was a lot less noisy.....it disappeared over the summer which leads me to think it�s only a problem with the enclosed water/radiator central heating system (ie not to do with hot or cold water supply to the shower/sink)

They knock in our bathroom, regularly, all night, (like chinese water torture......every couple of minutes, they knock about 10 times every 4/5 seconds). what causes this? How can I stop it? I�ve tried bleeding all rads, which improves things a little, but not much. And I swear the next time it happens and I can�t sleep I will take an axe to the buger (sic). The pipes are in the false roof space since that was easier to use as a pipe run than digging up the floor.....but now they�re all sealed in, and we can�t get at them without making big holes in the ceiling.....any other way?

What can I do? Many thanks all.

 

[inicholson]

I had a similar problem. It sounds like mine, which was water hammer. You can get this in the water system and it is caused often by water pressure. In the heating system it is often caused by pipes which do not have enough clips on them, allowing them to vibrate.

One thing I would try before punching holes is to check the thermostats on each radiator, if you have fitted them. My problem was actually caused by a faulty/loose thermostat. I managed to track it down, removed it, and the system is now fine. Remove one at a time and by the process of elimination you may find one that is causing the water hammer.

If this fails the one final thing you can try is temporarily tying the ball valve in your heating header tank to make sure it is not the ball valve that is causing the vibration.

Hope this helps

[Dedicated]

I think you may be a bit stuck there. It seems apparent that the pipe work is to blame for the problem. The only thing I can suggest is that you reduce the heating pump setting down a notch if at all possible. There is usually some sort of variable pump control on the pump itself. At the end of the day however you may well have to access the pipe work in order to secure it more firmly.
Another thing is that the centrally heated water may be becoming too hot. It may be getting near boiling point, the culprit being a boiler thermostat, or such. The worst scenario is that due to this constant banging over time the pipe joints may become loose causing them to leak.