DIY Doctor UK DIY Forums

We are having a problem after the central heating has warmed up we get abanging/chattering in the pipes, upon ajusting one or other of the vales it stops or if we turn down the boiler themostat. Should all the lock vales be fully open when you have thermostatic vales ? or should they be part open. When the banging starts should I go round and ajust the lock valve to restrict the flow. Any idea's Thanks in advance.

With all TRV's fully open there should be 10 to 15 degrees drop across each radiator adjusted with lock shield valves. Some TRV's need to have flow in one direction and reverse flow makes them bang. I also found out the hard way and had to reverse three valves. Some valves it doesn't matter with.

When the system starts up, check to see which end of the radiator gets warm first. If the opposite end to TRV the flow is the wrong way. Depending on the make of valve you might be able to just reverse them, otherwise you'll have to move the things.

Thanks for advice.I have turned down the pump speed from high to medium and it has solved some what the problem, they don't chatter as much. All the valves are two way flow so next job is when they start is to decrease or increase the flow by closing or opening the lock valve to see what effect that has. Will let you know how I get on.