Nest Thermostat Installation

[Ian Tait]

Hello all

New to this forum but hoping to get some great advise. I have purchased a nest version 3 thermostat with a heat link. My boiler is a potterton suprima 40, and has what seems to be a simple 3 wire programmer. There are only 3 connections for this programmer labeled CH out, DHW on, DWH off.
On the nest heat link there is 3 wire connection for the central heating and 3 wire connection for the hot water, Can any one out there let me know how to wire this up

Many thanks

Ian

 

[Darkwood]

Welcome to the forum Ian

 

[Octopus]

Welcome.

What instructions came in the box? Have you contacted the supplier?

 

[davesparks]

Are you an electrician?

 

[Samsparks]

Link permanent live to 2 and 5, ch to 3, dhw on to 6 and dhw off to 4.

 

[davesparks]

Link permanent live to 2 and 5, ch to 3, dhw on to 6 and dhw off to 4.

That won't work very well!

 

[Samsparks]

That won't work very well!

Why is that then? All depends how the programmer is wired at the minute 1 is heating satisfied, 2 common, 3 heating on, 4 hw satisfied, 5 common, 6 hot water on. Am i wrong? All depends if he knows how to adjust connections at 3 port valve to remove original thermostat assuming its a y plan.

 

[davesparks]

Why is that then?

Because by following your instructions he will be putting the best CH channel in series with the existing thermostat, which won't work as desired!

 

[Samsparks]

Because by following your instructions he will be putting the best CH channel in series with the existing thermostat, which won't work as desired!

My bad I should have pointed that out In the first place

 

[MFR]

Hi Ian,

I'm new too - in fact this is my first post, but I've installed quite a few nests.

First thing that you'll need to do is remove the existing room thermostat cable (usually a 3 core), as the nest is now working as the programmer & room stat in one.

Depending on your type of system it will effect your wiring, I'll assume you have a Y plan considering the fact that you have a 'hot water off'.

Your three wire connections for heat / DHW are as follows

1 - CH Normally Closed
2 - CH Common
3 - CH Normally Open
4 - DHW Normally Closed
5 - DHW Common
6 - DHW Normally open

As such you'll need to link a live feed across from your L terminal to 2 & 5.

CH ON Will need to be connected to 3
DHW OFF Will need to be connected to 4
DHW ON Will need to be connected to 6

These connections should return to your mid-position valve, make sure you leave the cylinder stat in circuit, and there isn't too far you can go wrong from there.

Cheers.