Central Heating

I have problem with my CH whereby first thing in the morning when the heating comes on it doesn't switch off when the thermostat temp setting is reached and continues to heat the house.

Anonymous user 28/02/2024 - 2.46 PM

If I switch the heating off and then back on, either at the CH controller or the fuse box, it seems to start behaving itself. In that if I turn the thermostat down, I hear it click and the boiler stops. For the rest of the day it is usually intermittent and again and not switch itself off when the thermostat temp is reached. This means constantly regulating by switching the CH off & on again. When the heating continually runs, regardles of the thermostat temp, if I check the postion of the Honeywell valve unit, it is in the open position. When I switch the CH off this obviously closes and when I switch the CH back on it stays closed. When the CH is behaving itself and I turn the thermostat temp up and down, I can hear the valve opening & closing as required. But then later on in the day the problem re-surfaces. My untrained thoughts are that it could either be a problem with the CH controller or with the Honeywell 3 port valve unit and it would probably be a case of swapping one or the other to identify. Any trained thoughts would be welcome. Thanks in advance. Sovereign & Glenbury - thanks for the responses. Glenbury, when you say the valve head do you mean the cover ? The cover does have a bump at the back and inside the model is V4073A1039. I am fairly good at DIY - could I buy one of these and replace it myself ? I wouldn't consider it if it meant draining the system but a direct replacement I would tackle