Water piper knocking - is this 'water hammer'

Most likely not water hammer. WH shows usually when a tap or ball valve shuts down. Your heating should not be drawing any water. More likely some pipework to your central heating is in the loft and is rubbing against a joist or other object and the expansion is making the knocking noise. Cure? trace the pipes and place lagging around the pipes where they rub against anything.

My CH pipes are rubbing on the joists under my floorboards in the bedroom. One hell of a racket when the system warms up in the morning.

Trace where the noise is loudest and secure the pie that's loose.

Beware of securing long runs of heating pipe. The expansion/contraction can create infurriating noise as the pipe periodically 'jolts' through the fixing. Like to know the best compromise for this myself, the previous owner thought that strategically placed socks were the answer.

-- Mike W

I wrapped mine with the 'carpet felt' type pipe insulation where they pass through joists etc. to forestall this problem. Fastening heating pipes down may make it worse if they haven't room to expand.

On Sat, 15 Apr 2006 17:32:44 GMT wrote in news:4E180F4EE4% snipped-for-privacy@lycos.co.uk:

Cheers all. Will get on it.

One about every foot?