Pipe banging

[AnonymousImport]

My radiators are fed from pipes dropping down from supply and return pipes running above the ceiling. Bathroom and hall radiators are fed from a single pair of downpipes. When either radiator thermostatic valve (Drayton TRV 4) shuts down, the supply pipes (or maybe the valve itself) bang until the valve is fully closed. All other radiatord are OK. Ideas please?

 

[AnonymousImport]

As far as I know, only more recent TRV4s are reverse flow capable, so check that the valves are installed the right way around. Also possibility of air in the system, or pump speed too high? Apologies if you've eliminated these already. Good Luck.

 

[AnonymousImport]

Thanks. Both TRV4s are later type, ie. reverse flow capable. Pump speed is lowest of the 3 available.

As the problem only affects this particular pair of downpipes (which are the ones nearest the pump/boiler, where do you think the air might be - and how would you remove it?

 

[AnonymousImport]

Did you try closing down the lockshield valves a bit? If these two rads are closest to the boiler, then they should be at least partially closed.

 

[AnonymousImport]

Thanks. Yes - both lockshield valves only open 1.5 turns.