Central Heating / Water not switching off

[CSutton]

Hi all,

I live in an 18 month old house and have a central heating system which has a heating circuit on the ground floor with a thermostat and another for both floors 1 and 2 combined. I also believe I have a separate circuit to 4 bathroom radiators which when we moved in I was told operated in both summer and winter time regardless of whether the heating was on and heated when the water was on.

I have 3 x electric powered Danfoss 2 port valves in my airing cupboard. The problem I have is that for some reason (possibly the pump) and water tank don't switch off and seem to keep calling for heat when both heat thermostats are off and not calling for heat and the water is not timed to be on i.e. all switched off.

The only way I can get it to switch off is if I move all of the Danfoss valves to manual and then back to auto which seems to work in switching off the tank pump/call for heat - but this doesn't always seem to work!

I suspect one of my Danfoss valves are faulty. Is this the likely cause of my problem or is it something else? How easy are they to change and how do I ensure this is the root cause?

Thanks guys in advance,

Cheers,
Chris

 

[PrenticeBoyofDerry]

If the levers on the port valves are not seized, but not responding to controls then it could be the Acuartor that has failed.

 

[CSutton]

To confirm the levers do sometimes respond when the heating goes off.

 

[Tibbot]

The only way you can trace the fault accurately is with electricity testing equipment. If working 24/7 you will have live at the orange wire of the offending zone valve with all other controls off but power on from fused spur. If all other controls are dead leading to it, you have a fault on the powerhead of the danfoss. You may wish to download a schematic wiring diagram to help.