tap-tap-tap central heating

[rhythmrikardo]

Since we had the builders in and they drained the system to fix a new radiator there is a tapping sound that begins when the boiler is firing. It starts fast and slows down over about 10 secs and is causing SO to get quite cross when she is attempting to get to sleep.

Originaly the pressure in the system was just over 1 and the builders left it at just over 2. I bled one radiator until the pressure was back down to 1 to see if the noise went away but it didn't.

I think the noise is coming from the pipe area where they exit the boiler but can't be too sure. I'm pretty sure that before the work all radiator valves were fully open.

What is the correct pressure for the system? Does anyone know how I can get rid of the tapping?

Thanks for any advice. Rich.

[.]

tension in the feed pipe would be my 1st guess. either re pipe it with copper or introduce a section of plastic pipe into the feed side of the system. FWIW I've had a similar problem recently after swapping 6 old rads for 6 new rads, plumber has introduced tension to the feed side of things and it's clicking on expansion and contraction.

obviously, I'm getting him back on the job to redo it properly.

[Roger Mills]

Unlikely to be anything to do with pressure.

More likely that the pipework has been disturbed and is undergoing a stick-slip action as it expands, at the point where it passes through holes in woodwork or over notches in joists. You simply need to wrap the pipes in felt wherever they are in contact with anything, so that they can slide smoothly when they expand.