I have a problem that has just sprung to light.
I have a traditional wet central heating system with a pumped rad circuit and a gravity hot water circuit. I am running a Honeywell ST699B controller and a thermostat in the lounge. The radiators have started operating even if the heating control on the ST699B is turned to 'off'. The only way to prevent them running is to turn the thermostat down. I think it is a 3 way valve problem? Any ideas?
I have a traditional wet central heating system with a pumped rad circuit and a gravity hot water circuit. I am running a Honeywell ST699B controller and a thermostat in the lounge. The radiators have started operating even if the heating control on the ST699B is turned to 'off'. The only way to prevent them running is to turn the thermostat down. I think it is a 3 way valve problem? Any ideas?