Can you help. I have a central heating system which seems to heat up ok, however, after about 1/2 an hour there is a noise (like air in the system) comming from the pipework above the boiler (boiler sited on the wall in the kitchen) When I turn the central heating pump from 2 to number 1 the noise stops but the hot water does not heat up. I have changed the pump but the problem is still there.
Thank you for responding.
It is a Glow Worm Ultimate, I think system boiler (has a water cylinder pump and diverter valve.) I am not able to get it to make the noise when the system is up and running and at room temperature, during the day. However, It seems to be happening when heating up first thing in the morning and after about 1/2 an hour the pipes above the boiler start making the noise.