Nest thermostat has stopped heating but hot water OK

[Jpwood1]

Overnight my Nest thermostat has stopped firing up the boiler for central heating but works fine for the hot water. I have checked the heat link and I can hear clicks when I turn on and off the heating but nothing happens to the boiler? Can anyone help with this ? 

[Frustratedddd]

Sounds like a motorised valve in your system, not the Nest if you have tested the Heat Link

[Jpwood1]

It was the motorised valve that had gone, that has been replaced and all is working fine again. 

[Frustratedddd]

Everyone thinks the thermostat is the guilty part, but never look at the obvious! 

[Jpwood1]

I tried looking at the whole system and had my own suspicions that it was the valve but wanted to check from others who know more about plumbing and you helped by confirming my suspicions.