Nest Heatlink CH not working

[BrianMcC]

Hi All

I would appreciate some advice. I have a 3 circuit conventional heating system (downstairs radiators, upstairs radiators and hot water, hot water tank upstairs) controlled by nest app and 2 heat links ( one for upstairs and one for downstairs + hot water). Standard system Worcester boiler. Downstairs/ hot water heat link was replaced by Nest last year and all worked fine till a few weeks ago. 

Now the downstairs radiators do not heat on their own - even though the app indicates heating is on , I hear a click at the heat link and the motorised valve opens.  The boiler does not come on.

But the downstairs heating works fine if also run with either the hot water or upstairs radiators. It also works in manual mode (this turns on HW and downstairs radiators). App is running latest software and WiFi / pairing is fine. I have returned the app to factory settings and reset the heat link to no avail. 
It doesn’t seem to be a stuck valve as it powers up appropriately, I can hear it open and it works in manual mode as well as with the HW and/ or upstairs radiators on.

Reading here there is mention of a possible contact problem in the heat link? Should I call Google/nest or my heating engineer?

 Thanks 

[Frustratedddd]

You can test the contacts easily if you have a simple neon screwdriver or a tester. Open the Heat Link cover and test them there, that proves the Heat Link is switching.

[LarisaL]

Hi there, thanks for reaching out! I'm so sorry to hear about this issue. Please go near your Heat Link and activate the boost for hot water from the app and let me know if you hear a click. You should hear a click when you boost the hot water and another click when you stop boosting it. Just to make sure that the relay is working properly, please try that 5 or 6 times and let me know if you hear a click at every command. Also could you please tell me if you have a separate valve for the heating and hot water, or you have just one handling both? 

[Vladut]

Hi there, just checking in with you. Did you manage to check the last message?