What Are The Symptoms of Faulty Motorised 3-way Valve?

[kaithavallapil]

My central heating has worked fine for years, but recently became troublesome because the heating never seemed to switch off when the room stat went off. When the HW stat is calling for heat, the rads also get hot. I changed the room stat and the HW tank stat (both were very old). This improved things, but now the heating problem is intermittent and I suspect the motorised valve.

The problem seems to happen on really cold days when the heating has been running for a long time and I suspect that the motorised valve gets hot and this messes with the internal electrics.

Does heat affect a motorised valve actuator?

Things seem fine when not much heating is required, but on the really cold days when the demand is high and the boiler is working flat out for many hours, the rads stay hot with boiler working and the pump still circulating even after the stat has switched off. I have to switch the programmer off to get stop this happening. On warmer days, everything seems fine.

I have a Potterton 3-way motorised valve and can change just the actuator.

Any suggestions?

 

[Burnerman]

It depends whether the valve is sticking, or the powerhead is getting grumpy....I've got exactly the same problem with a Honeywell V4044F, which is nearly £150!
John

 

[seco services]

the rads stay hot with boiler working and the pump still circulating even after the stat has switched off. I have to switch the programmer off to get stop this happening. On warmer days, everything seems fine.

sounds like your still getting power on the white wire to the 3 port valve.