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Hi just bought a nest e thermostat . Ive included a picture of the wiring for the old thermostat and the connections for the new nest thermostat. I just want to make sure it’s compatible before I get someone to install it. Which wire goes to which connector for want of a better question ?

AB705A6B-6730-4222-BD70-1A4E80A77B2A.jpeg

3AA56283-AF5F-40BA-A776-7DBF5C57EFBD.jpeg

F36F5F7D-E355-4D82-B45B-682297E41ED9.jpeg
 

Midwest

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Arms Access
Does seem unusual not to have a neutral at an old existing room stat. Someone moved the existing stat in the past?
 

telectrix

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Arms Access
you need a 3core/E cable instead of the T/E.
 

James the Spark1976

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Arms Access
Esteemed Member
The nest thermostat is a combination of time clock and thermostat.
The base “receiver” unit can be fitted next to the boiler where there will be all the cables that you require.
The control or thermostat unit would normally be placed wherever the old thermostat is mounted and only needs 2 cores. This is to supply power from the base unit to the stat unit, as per the instructions.
All the control signals are sent wirelessly from the stat to the base unit.

Although this could be done by someone good diy skills and electrical knowledge, I would recommend getting a professional in to do it.

A mistake in the wiring could do any of the following.
1. Write off the boiler control board
2. Write off the nest thermostat
3. Cause a shock or other injury
4. All of the above at the same time.

As long as you have a wire with at least 2 cores going from the boiler to the old stat, a professional should have you up and running within the hour.

P.s. for the techs reading this, the only function of the link wire from base unit to stat is to supply 12v dc to the stat for its own power.
 
  • Thread Starter Thread Starter
  • #9
Hi again, can I just clarify that this is a nest thermostat E that uses the heat link at the thermostat with nothing fitted to the combi boiler itself (obviously the thermostat connects to the boiler at that point). I’ve just spoken to nest tech support and told her that I only have a 2 wire system and she seemed very confident that they will connect to the C and NO and that the system will work.
 

telectrix

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Arms Access
Is N neutral?

Gas was only installed about ten years ago
N is indeed neutral.
Post automatically merged:

The nest thermostat is a combination of time clock and thermostat.
The base “receiver” unit can be fitted next to the boiler where there will be all the cables that you require.
The control or thermostat unit would normally be placed wherever the old thermostat is mounted and only needs 2 cores. This is to supply power from the base unit to the stat unit, as per the instructions.
All the control signals are sent wirelessly from the stat to the base unit.

Although this could be done by someone good diy skills and electrical knowledge, I would recommend getting a professional in to do it.

A mistake in the wiring could do any of the following.
1. Write off the boiler control board
2. Write off the nest thermostat
3. Cause a shock or other injury
4. All of the above at the same time.

As long as you have a wire with at least 2 cores going from the boiler to the old stat, a professional should have you up and running within the hour.

P.s. for the techs reading this, the only function of the link wire from base unit to stat is to supply 12v dc to the stat for its own power.
so, if i read your right. ( bear in mind i have no knowlege of nest), he needs a 3core/E (or 4 core flex) from boiler to receiver, and just a pair to the actual stat., which mus be RF to the base unit?
 
  • Thread Starter Thread Starter
  • #12
I’ve just found this installation video. Is this not exactly my combination of wires brown, blue and yellow/green

5mins 50 in..

 

telectrix

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Arms Access
with your existing stat, brown is L, blue is switched L. Gn/Y is earth.there is no neutral.
 
  • Thread Starter Thread Starter
  • #14
Oh , now my head is hurting, I won’t even pretend I understand and now beginning to think I’ve wasted my money , thought this was going to be an easy swap over
 
  • Thread Starter Thread Starter
  • #16
Yeah I’m going to get a professional to do it for me, he’s doing it as a favour so I really wanted it to be as simple as possible and that’s why I bought the E . It’s also a housing association property so if it’s going to require a neutral wire installed then I’m probably going to require permission and other red tape before I can go ahead which will probably lead me to just not doing it.

I’m curious to know why telectrix knows it’s a switched live and not a neutral as every website I’ve looked at says neutral is a blue wire. Is it to do with the wiring diagram I uploaded?
 

westward10

Moderator
Staff member
TA
Arms Access
You need to ignore the fact it is blue the installer should have put brown sleeve over it.
 
  • Thread Starter Thread Starter
  • #19
No that’s why I said it would hold things up. I’ve been told if I fit a nest they won’t maintain it and would only replace it with basically what’s in now .
 

buzzlightyear

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Arms Access
most housing associations dont like people playing with their boilers or other things just in case their is a mishap .
 

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