"Kevin Rayner" wrote in message
...
How can I tell whether the motorised valve on the hot water circuit is
working correctly. I have been having a few problems with cold water and
noticed that the manual/auto lever on the valve has no action. Operating
the
lever on the central heating valve has some resistance and is working. The
lever on the HW valve has no resistance what so ever.
Do I need to replace the whole valve?

Hopefully not unless the whole thing is seized.
If it's a Honeywell-type valve it is possible that the motor has packed up.
I have had them go about once in three years on average. A new actuator --
just the top part -- from Screwfix costs 8 quid and they are not too
difficult to fit. I keep a spare one in the house because they always go at
weekends. If the problem is no HW flow try opening the valve manually with
the lever: make sure the system and thermostats are 'on', then if HW comes
through it's probable the actuator has failed, especially if the flow ceases
when you allow the lever to run back under the spring. You probably know
that these valves can be kept open manually -- there is a cut out that the
lever can be 'parked' in.
HTH
mutley