Radiator 'tapping' noise All aspects of plumbing questions and answers, help, tips and information

[Lawrence]

I have recently started to get 'tapping' noise from my radiators. I've got TRV4s on (nearly) all radiators. The system is about 12 years old, open vented, with a regularly serviced boiler.

Any idea why it's just started to make the 'tapping' noise and is there a way to resolve this? Does it, for example, need a power flush?

thanks

[bjbiker]

Early TVRs had to be installed on the flow where as new ones are almost all flow or return.
If an older valve is fitted on the wrong side it could start tapping as it closes, test by turning heating on and see which pipe to rad gets hot first!

[Lawrence]

thanks bjbiker. I'll check the TRVs tonight. Something else you may be able to shed some light on..... should the water in the central heating F&E tank be warm? Mine is - and it is very dirty as well. I recently put in sludge remover and flushed the system a couple of times, then added corrosion inhibitor but it is still obviously circulating some very mucky / rusty looking water.

Is it worth getting the system power flushed?

[bjbiker]

Hi Lawrence,
Power flushing is the most effective way of cleaning the system as you turn off all rads and flush one at time, there is also a tool available that attaches to a drill and vibartes the bottom of the rads dislodging sludge.
Water in header tank may get warm, but make sure system isn't over pumping into feed and expantion tank! also check for correct level in F&E tank, when system is cold water should be below half full but above the feed (outlet pipe.)
Good luck
Bjbiker

[Lawrence]

Hi bjbiker

well, I've had the system powerflushed and I've been told the system isn't overpumping.

Something else I've noticed however, the feed pipe from the F&E tank is as warm as the flow pipe to the pump so presumably that's why the water in the F&E tank is warm? (the feed pipe joins the flow pipe before the vent pipe and approx 12" before the pump). Is that also why I am getting water (condensation) dripping out of the overflow pipe - I can't see any other reason for this as the water level in the tank is below the overflow level.

Is there anything I ca do to stop the water dripping from the overflow assuming it's condensation?

thanks