Honeywell 2 port motorised valve screeches when shutting off

[Del9110]

Hi all, I have a 2 port motorised valve that screeches when CH shuts off, this has been ok for 6 months. System is a combo boiler operating 2 zones CH & underfloor heating with a safety PR valve. Both valves plumbed correct flow direction, is this classic water hammer from a defective ball/plate or head? All help appreciated. Thanks

 

[PETE 123]

new motor or change head

 

[king of pipes]

Any pictures please ? Is there a auto bypass fitted before the zone valves it sounds like it will need replacing. Kop

 

[Del9110]

Any pictures please ? Is there a auto bypass fitted before the zone valves it sounds like it will need replacing. Kop

Thanks for the replies, the motor was changed as a cheap first fix that didn’t solve, going to change the head. Pic will hopefully be attached.

 

[king of pipes]

Looks ok there check the operation of the small spindle where the power head connects it should move freely by hand and try firing the boiler with the power head removed to check it opens and closes . Kop

 

[SRafiq]

Anything more on this. I have similar problem.