Nest Link not starting CH after 6 years good running.

[damastes]

Hi, hoping I can get a little assistance here before I call out an engineer.  We had our Nest set to eco over the summer, as per usual.  This year, when turning the heating on there was no response from the boiler.  We called an engineer out from Vaillant thinking it was a boiler fault, however when he arrived and we turned the heating on to show him the issue it fired up without a problem.  Since then the heating has worked, until this morning.  Yet again, no response from the boiler.

So far I have tried/confirmed;

• Manual switching on of the CH from the boiler control panel works fine, so we can get heat into the house we just have to turn it on/off manually.
• Turning on heating from the Nest Link does not start the CH, but there is a click from the relay in the box.
• Turning on heating from the Nest Thermostat does not start the CH, but there is a click from the relay in the Nest Link box.
• Power cycling the boiler and Nest Link does not fix the issue.

All this, in my mind, would point to an issue with the heat signal wiring between the Link and boiler.  I'm wondering if there is a bad or loose connection?  Hoping there is a fix that I can carry out without having to call someone out 🙂

[AlexD]

Thanks for reaching out here @damastes and for the extensive details. I am sorry to hear you are facing difficulties with your device and I would be happy to try and assist. 

Just to check, how long has the thermostat been installed for before you first noticed this behaviour occurred? Also do you only control heating from the thermostat or does it also control the hot water? 

[damastes]

Nest was installed around Jan '17 so coming up on 7 years now.  The first time this happened was a few weeks ago when we first turned the CH on again after summer.  Since this post it started firing up again, however today there is barely any click from the Nest Link when the CH should turn on, so I am fairly certain it is the relay that has given up the ghost.

[damastes]

Oh, and to answer all of your questions, it's a combi-boiler so hot water is on demand.  The Nest controls central heating only.

[damastes]

Resolution to this, I have Boxt coming out in 2 days to replace the Nest Link.

[Vladut]

That's great. I'm really happy that everything is sorted. Let me know if you need anything else.

[Vladut]

Hi there, just checking in with you. Do you still need help?

[damastes]

All good now thanks 😄

[Vladut]

Great. Let us know if you need anything else. We're one message away!