by dwedmunds »
Fri Mar 08, 2013 5:08 pm
When the central heating boiler stops there is a rumbling sound from the pipes, sometimes accompanied by a sharp knock sound. I can eliminate this by turning down the two gate valves on the pipes leading to the hot water tank in the airing cupboard but only if the valves are turned about 75% off. What causes this & how can I overcome the problem without having to turn the valves down so low? Apart from this the CH system works OK.
