Nest Wiring issues 3rd Generation

[Dan Bate]

Finally had the time to sit down and do this properly. I took all the wiring centre apart and tracked all the wires back. I then reinstalled and it now works. Thank you everyone for your support and help.

 

[Ariel Cohen]

Was your nest heat link faulty at the end or was it just your wiring that was wrong causing you to have perminant live from terminal 3?

Im having a similar issue and not sure if I've done my wiring wrong or if my heat link is faulty and needs to be replaced. No matter what I do I get live from terminal 3,even when no call for heat etc.

Thansk

 

[Deleted member 267285]

Ariel, do you have any testing equipment?

 

[Ariel Cohen]

I have a multimeter, neon screwdriver and voltage tester.
I havent used the multimeter yet but terminal 3 is calling for heat constantly.

I have a combi boiler with split floors, both nests are wired the same, one works and the othet doesn't.

Yesterday I noticed I can't seem to remove the screw from terminal two, either it's thread is gone or its melted shut.

Thanks for your help

 

[Deleted member 267285]

If you know it’s definitely calling for heat without testing, then I’d say faulty Heatlink. If you want to test it, leave Live and Neutral connected, disconnect terminal 3, and test Volts AC between Neutral and 3. Or disconnect everything and test continuity between 2 and 3.

 

[Ariel Cohen]

Did continuity test between 2 and 3 and coming up as connected.

I also did a reset of heat link twice and reconnected to thermostat and its same problem.

 

[Deleted member 267285]

Did continuity test between 2 and 3 and coming up as connected.

I also did a reset of heat link twice and reconnected to thermostat and its same problem.

Faulty heat link then.

 

[Ariel Cohen]

Yes and Nest won't send a replacement as warranty finished in October 2021

Surely these things are meant to last longer the a couple of years? They wouldn't even put me through to a manager. Point blank refused, saying I would be told the same thing. Shoddy Customer service from Google.

 

[Ariel Cohen]

I did here the click when the tempt goes up, so not sure what's wrong with the relay, have half a mind to try and unsolder the relay from the hot water and move it the heating side as I've got a combi boiler and the water water side isn't used.

 

[Deleted member 267285]

Depending on your boiler make and model, you could use T1 and T2?

 

[Ariel Cohen]

That's a really good idea, unfortunately my boiler is the worchester 4000 which doesn't support open therm.
Can I still get t1 and t2 to work even though my boiler doesn't support open therm?

Thank you

 

[Deleted member 267285]

No, sorry, it’s just opentherm that‘s supported. 2nd hand heat link or other option might be to purchase a relay, but it’s a bit past my understanding of it, sorry.

 

[Ariel Cohen]

If you have a second hand heat link please let me know?

Thanks for all your help

 

[Deleted member 267285]

Sorry, just re-read. OT1 and OT2 are the opentherm, T1 and T2 are to power the thermostat only, 12vdc outgoing.

No sorry, I don’t have a 2nd heat link.