Just checking in to say thanks for your input - we were almost due a (heating) service and the engineer was able to call earlier than expected; the valve was indeed the culprit (as you said). He charged an extra £60 for the valve.
Well that little test produced no heat; I guess that means its NOT the thermostat and the problem is ???? Any advice on whats the next logical thing to test would be greatly appreciated.
Not for the heating no; there are settings in there (Daikan system) but its all water temperature etc.
We havent activated the heating for many months - I guess a lot of people are similar; turning it on before the colder months hit us...
We have underfloor heating downstairs and thats working fine; with zonal thermostats; its only upstairs that is failing - hence looking at the thermostat first. Am I right to assume joining these wires should bypass the thermostat and call for heat ?
Looking for confirmation that joining the 2 wires (COM and N/O) should bypass the thermostat and trigger my heating.
Im trying to isolate the problem.
Pics attached.
This is a Danfoss TP4000
TIA.