Noisy Motorised Valve

6 Nov 2007
Reaction score
United Kingdom
I have recently replaced a faulty 2 port MV ( ACL Drayton ) on the CH zone with a Horstmann 2 port MV. Everything appears to work OK but there is a brief but very loud clanging noise from the pipework around the MV when the system calls for CH and the valve opens - whether this call be from the programmer or from the room thermostat. There is also a slight clunk when the valve closes.
The valve appears to open and close properly, all rads are working efficiently and without air locks, and the system works quietly other than at the open/close phase of the valve.
The MV supplier suggested it must be a faulty actuator and replaced under warranty. Having firstly replaced the actuator and then the valve too the problem is still there. Wiring seems to be OK as the system, incl the HW supply and MV, all works properly as per program.
Is this a valve compatibilty problem and should I simply replace with a new ACL valve ?[/list][/quote]
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Are you sure the valve is fitted in the correct direction for the pump flow?

Which setting is the pump on?

Do you have an auto bypass valve?

Thanks Tony

Yes the flow is in the right direction and can feel the flow through the valve and pipes. The pump is on No 2 setting. Tried 1 But didnt seem to make any difference.

Not sure what an auto bypass valve is !
You have fitted the valve wrong way round, port b needs to go to flow.
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OK, thanks. Will refit and try altho hot water flow does seem to go A to B as shown on MV fitting instructions.

The pump has isolation taps and easy therefore to remove. Can this be reversed temporarily to test the solution ?


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