Westherm RV hammering

[AndyDB]

Can you help please?
I have two Westherm Radiator valves which 'hammer' as they reach the preset temperature. All the other radiator valves are fine.
The hammering appears to be in the right-angled pipe joint, not the head unit. Looks like I'll have to renew the joint, but I want to avoid a drain down. Or is it system pressure or something else?
All advice welcome!

 

[kevplumb]

the flow is going through the valves the wrong way

drain down or not depends on your system and abilities

 

[D_Hailsham]

Is there a single arrow or a double headed L-shaped arrow on the valve body?

If it's just a single arrow this must be in the direction of flow (towards rad on the hotter pipe, away from rad on the colder pipe. If it's an angle valve the head will be vertical when connect one end and horizontal when connected the other

Valves with double arrow can be installed either end with the head vertical or horizontal.

If the valve is the correct way round, the problem may be too high a pressure in the system. The bypass valve needs to be adjusted. This will either be in the boiler or near the pump.

 

[AndyDB]

Thanks guy's; I'll check this out. Andy.

 

[AndyDB]

Thanks for advice, the flow is going through the valves the wrong way!

 

[kevplumb]

----------------------------------------------------------------------------------------^