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I have a central heating system containing 16 radiators with the pipes running under the floor boards. For the passed 24 years I have experienced a constant continuous knocking in the pipes passing between and underneath two adjacent radiators when the central heating is on. The problem does not occur anywhere else in the system. I have had numerous plumbers to investigate the problem over the years but no one appears to be able to solve it. Can you help?

Hi there,

Are the pipes lagged and secured with clips?

AH

[quote="Selby Bailey"]I have a central heating system containing 16 radiators with the pipes running under the floor boards. For the passed 24 years I have experienced a constant continuous knocking in the pipes passing between and underneath two adjacent radiators when the central heating is on. The problem does not occur anywhere else in the system. I have had numerous plumbers to investigate the problem over the years but no one appears to be able to solve it. Can you help?[/quote]

Hi there,
I'm no expert, but I think this has something to do with the hot and cold pipes touching each other....have a look to see if they are touching and also if the cut-out is deep enough in the joist.
good luck

rose,
If you mean a continuous regular knocking sound the most likely cause is that the jumper on the valve on a radiator fed by the pipe is loose and is suddenly turning off the flow to the radiator. Check by opening the valves (both ends) on radiators fed by the noisy section of pipe.
end

clipped?

CkW

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