Boiler wont stop despite thermostat

[JCollis]

My thermostat is set at 14 C overnight but the boiler keeps pumping out heat so it was 24 C at 5am. The only way to stop the heating is to turn off power to the boiler . 
I installed Nest a month ago and so far my gas consumption is double what it was with the previous system. 

[JCollis · Accepted solution]

seems loads of people have the same problem and Google provides no sensible answers.

[Frustratedddd]

My first question would be who installed the thermostat? Are you UK?

Are you saying that the thermostat display shows the reading as 14C, and has a black colour display not orange, but the heating is still running? Can you hear the pump running even when the thermostat is set to off? Check this at the display not the app.

[JCollis · Accepted solution]

Yes I’m in the uk so thermostat communicates with the Link which controls the heating/ hot water pumps. 

[JCollis]

yes I can see the boiler is running and the radiators are hot . I have rebooted the Hub but that doesn't change anything. The thermostat says the heating is off but it isn't.

[JCollis · Accepted solution]

seems loads of people have the same problem and Google provides no sensible answers.

[Frustratedddd]

Yes I agree, and who installed your thermostat?

You say reset the hub, do you mean the Heat Link?

[JCollis]

Yes the Heat link. I power it off. I’ve made some progress moving the thermostat closer to the Link (10ft) . It seems to turn off the heating now but now the hot water doesn’t go on when the heating is off despite the schedule. If I hit ‘Boost’ on the HW the heating goes on as well even if the temp is well above the thermostat setting. 

[JCollis]

Yes. Turned power off. Have now moved thermostat closer to the Link and reconnected. Thermostat is set to 17 says temp is 18.5 , green leaf shows but boiler still going strong.