Gas boiler non-reacting to NEST after normal functionality

[CurrentlyCold]

Hi,

Our UK gas boiler (on/off; 24V system; nest thermostat E, UK) does suddenly/intermittently not react appropriately to the NEST input anymore, after having run without any issues for many months. 

It started after the heat system not having heated for several months during summer with the first heating episode. The first system turned on fine after temp fell. However, then the boiler didn't stop anymore despite NEST showing temp reached and not sending heat signal anymore. Even  when switching NEST heat to 'off' the boiler still fired. After restarting boiler multiple times this stopped. Following this there have been episodes when NEST triggered heating appropriately but also longer episodes when boiler has been non-reactive to when nest showed heating on display and on heat link. No error message ever on Nest unit.

Many thanks for help.

[AlexD]

Thanks for reaching out to us here @CurrentlyCold and sorry for the late reply. 

If the thermostat seems to be reacting correctly it is possible that this is an issue with the boiler itself.

You can do a click test. Stand with the Nest app next to the Heat Link, turn the heating off and back on from the app and listen for a clicking noise from the Heat Link. It should click when turning the temperature up past the ambient temperature and again when turning it down. 

If you hear a click both when turning the heating on and off, it would indicate the Heat Link is working as expected. 

In this case it would be best to get the assistance of a Nest Pro or your preferred installer to check the system. 

Best regards,

AlexD