I have just replaced a very old room stat which had 2 red, 2 black and an earth. Drayton technical told me the wires to use from the old stat which involved taping off two of the wires as only two are needed for the new stat which are common and on.
When set temp calls for heat, boiler fires up, 3 port valve moves to heating position and all fine. When room gets to right temp, boiler switches off. All OK. When heating turned off at main timer unit and HW is called for, boiler fires, 3 port valve moves to HW position and all OK.
The problem arises when both HW and heating are on on the main timer box. When room temp is up to correct temp, Digistat 3+ turns boiler off, but 3 port valve does not "park" at the HW position which means that if HW is being called for and pump is running, hot water is still being pumped to the rads. It is only if the heating is switched off at the main timer box that the 3 port valve returns to the HW park position.
I've called Drayton who say that as the room stat is causing the boiler to fire the wiring is OK and it could be either a faulty tank stat (I've turned this through the temp range and the relay clicks when calling for heat so that seems to be OK) or faulty room stat. Any suggestions please.
When set temp calls for heat, boiler fires up, 3 port valve moves to heating position and all fine. When room gets to right temp, boiler switches off. All OK. When heating turned off at main timer unit and HW is called for, boiler fires, 3 port valve moves to HW position and all OK.
The problem arises when both HW and heating are on on the main timer box. When room temp is up to correct temp, Digistat 3+ turns boiler off, but 3 port valve does not "park" at the HW position which means that if HW is being called for and pump is running, hot water is still being pumped to the rads. It is only if the heating is switched off at the main timer box that the 3 port valve returns to the HW park position.
I've called Drayton who say that as the room stat is causing the boiler to fire the wiring is OK and it could be either a faulty tank stat (I've turned this through the temp range and the relay clicks when calling for heat so that seems to be OK) or faulty room stat. Any suggestions please.