Smart Thermostat Permanently calling for heat
This is slightly different from everyone else's fault regarding calling for heat when not required, so thought I better to start a new thread.
Like a lot of you, I have heating coming on all night, even though every Radiator Thermostat and the Smart Thermostat are well below the temperature.
I checked and found the heating valve off the boiler was permanently open. I replaced it with a new one and had the same result. I bought a new heating controller and still have the same result.
Because I have wired my heating/hot water system with a 13 amp socket for ease of working on it, I turned it off and the heating valve closed correctly.
Turned the power back on and the valve opened.
I have now removed the Smart Thermostat and the valve closes. On the back of the Smart Thermostat you can see the pins that are for Common, NO - Normally Open and NC - Normally Closed. You get this information off the back plate still on the wall.
When no heat is required the NO should be open.
I found with every Radiator Thermostat turned to it's lowest temperature and off, along with the Smart Thermostat, there was still continuity across the NO pins. This should only happen when a thermostat calls for heat, which in turn will change the valve to open and start the boiler.
This means that it is very likely the Smart Thermostat which is at fault.
I have been in communication with Tado, but to be honest I am at a loss to describe just how bad some - but not all - of their support staff are. The one I am currently dealing with kept asking the same question. "Tell us the time and date the heating came" Even though I kept explaining that it was happening all night and turning on for 30 - 60 seconds every 2 - 3 minutes. To be more accurate than that we would need to synchronise our clocks!
I have fed this information to them and explained that as an electronics engineer, this was straightforward and as I had explained from the beginning, almost certainly a Smart Thermostat fault.
Annoyingly, I threw away my old thermostat recently!
Unless I have missed something, what I need from Tado is a replacement Smart Thermostat!