Nest thermostat wiring setup help!

[emmeth92]

Hi there,

After unsuccessful attempts to wire up a Hive thermostat, I am now trying to get a Google Nest to control heating in my home.

While the thermostat connects to my app and appears to be working on paper, turning the heating on and off do nothing - either the boiler will stay on if I have phgsically set it to that as usual, or it will stay off if I physically turn it off.

I am attaching pictures of my setup along with the wiring that was there from the previous inhabitants who also had a nest - any help would be greatly appreciated

 

[flameport]

What are the black and grey wires connected to in the boiler?

 

[emmeth92]

Alas, that I am not sure of ‍

 

[CBW]

Alas, that I am not sure of ‍

Can you check?

 

[CBW]

Boiler has low pressure and is set to hot water only on the selector switch.

 

[emmeth92]

Can you check?

I cant unfortunately, I amnt able to acces the area where they connect to.

Also the picture there with the low pressure gauge and on hot water only is dated, usually the dial is turned to the heating when on and the pressure is fine

 

[CBW]

What thermostat did you have prior to any work being carried out? Is the heating permanently on a new thing with the Nest?

 

[RandomGrinch]

What thermostat did you have prior to any work being carried out? Is the heating permanently on a new thing with the Nest?

We've been here before...

Thread 'Wiring switching from Nest to Hive' https://www.diynot.com/diy/threads/wiring-switching-from-nest-to-hive.618532/

 

[emmeth92]

We only moved into the house a few months ago and there was an old nest there, but we've only just replaced it.

We manually turn on the heating on and off using that knob on the left hand side of the picture above.

 

[CBW]

We've been here before...

Thread 'Wiring switching from Nest to Hive' https://www.diynot.com/diy/threads/wiring-switching-from-nest-to-hive.618532/

Good memory!

 

[CBW]

We only moved into the house a few months ago and there was an old nest there, but we've only just replaced it.

We manually turn on the heating on and off using that knob on the left hand side of the picture above.

I’d say there could be a link inside the boiler then that might need removing. Why can’t you access the wiring?

 

[emmeth92]

We've been here before...

Thread 'Wiring switching from Nest to Hive' https://www.diynot.com/diy/threads/wiring-switching-from-nest-to-hive.618532/

Yep, called that out in my original message here - can you help?

 

[RandomGrinch]

Yep, called that out in my original message here - can you help?

We concentrated last time on purely swapping the thermostats over from Nest to Hive - although I don't know if we ever asked the question...
Did the original Nest operate correctly, before you decided to swap it?

You seem unwilling to follow where the cable goes, but do you have any other controls, zone valves, or a wiring centre etc.?

 

[emmeth92]

I’d say there could be a link inside the boiler then that might need removing. Why can’t you access the wiring?

So the original Nest was missing the actual thermostat (presumably taken by the previous owners) so I have no idea if it worked or not, although the light on the heat link would blink so presumably it did.

On following the wires, I genuinely can't see how I can look without professional help (I am a truly clueless amateur here) as the boiler is attached to the wall and I cant access the area behind where the other end of the cable disappears up into. I can send a pic to explain if it helps!

 

[CBW]

No pic necessary. It’s quite easy, if you feel confident, and I don’t recommend this for just any boiler but yours is fine. Be careful as it’s mains voltage. You could turn power off to be safe.

There’s 2 screws on the front - if you look at the drop down panel there’s 2 magnets which align with the screws. Undo these slightly, lift off the outer cover. Then undo screws fully, being careful not to lose them.

Allow panel to drop down, follow cable on the left to a plastic housing, which I think is 1 screw, undo this, remove and you have access to the wiring.