Drayton LP241 and thermostat to Google Nest

[Edward Douthwaite]

Hi Guys,

I recently purchased a Google nest and am attempting to install it. The heating timer is a Drayton LP 241 and is wired as per the image.



The thermostat is wired as per this picture:



I understand that the wiring in the heat link supped by Google requires the wires to be moved to different locations, but do not know why I have 3 wires into the neutral at the timer.

I am unsure which wires would be required to connect at the thermostat side ( I need t1 and t2 to be connected - where does this supply originate?

Is there a way that I can configure the current wiring to power the thermostat, if so, how would I go about this please? I would like to keep the current thermostat location, if possible.

Any walk-throughs, advice would be massively appreciated.

Many thanks,

Ed

 

[stem]

First of all, which version of Nest do you have?

There is the 3rd generation Nest which has a Heat link as per the below which replaces the programmer and provides control of both heating and hot water

Or the Nest-e that only controls the central heating and just replaces the room thermostat. Its Heat link looks like this:

They are different products and are installed differently.

 

[Edward Douthwaite]

Ho Stem,

Thanks for the reply, I really appreciate this. I have the 3rd generation Nest, with the heat link.

I've seen the wiring diagram for the heat link and read a couple of older threads which explain which terminals are required to be utilised at the heat link.

I have a relatively new ideal logic boiler and a wired thermostat in the system. Is it possible to wire in the heat link and thermostat with the wiring i already have in situ, or will more work and extra wiring etc be required?

Thanks in advance,

Ed

 

[stem]

The Drayton connections as printed on the back of it are:

I usually site the Heat link where the programmer is currently located and just move the wires over.

All of the existing wires are transferred as they are connected now, from the Drayton to the terminals at the Heat link that have exactly the same function as shown below. [You may find it difficult to get three wires in the Heat link N terminal so you may need to use an additional screw connector and then just take one wire from that to the Nest N terminal. Same thing will apply for the earth connection]

So in your case:

1. CONNECT THE HEAT LINK

Wires in Drayton N, L, E.....> Nest N, L, E

Wire in 1 (HW off)....> Nest 4 (HW Satisfied)

Wire in 3 (HW on)....> Nest 6 (HW Call for heat)

Wire in 4 (CH on)....> Nest 3 (CH Call for heat)

Then both Nest 'Common' terminals 2 & 5 should be connected to Nest L terminal

2. CONNECT THE NEST THERMOSTAT
If you wish to power the Nest thermostat from the Heat link then connect T1 and T2 at the Heat link to T1 & t2 at the thermostat, or alternatively use a separate plug in power supply for the thermostat.

3. DECOMMISSION THE ORIGINAL THERMOSTAT
The old thermostat should be decommissioned to stop it interfering with the Nest. The easiest way if you don't mind leaving the old stat in place, is to move the yellow wire from terminal 3 and put it in the L terminal with the red wire. If you want to remove the old thermostat, you should trace the thermostat cable back to its origin. When you find its origin, note where the red and yellow wires are connected. Now remove the cable completely and insert a wire to link together the two terminals where you have just removed the red and yellow wires from.

Whether the now disconnected cable can be used to connect the Nest thermostat to the Heal link T1 & T2 will depend on how the original installer wired it in. You may find the other end of the cable is terminated somewhere else than where the Heat link is located. On the other hand, it could be exactly where you want it to be.

 

[Bash_Bash]

Sorted.