Drayton LCW1 C Plan System? Google Nest 3rd Generation Help

[33-45-00]

Hello, I hope you are well, I’m planning on replacing the current CH/HW controls with a Google Nest.

I’m pretty sure I’ve got it figured out but just wanted to double check with somebody with more experience,

So the current setup is pretty similar to the attached diagram I think the only time its beeen touched since new 1996 is when the boiler was replaced and cylinder stat was.


So from the attached diagram and the nest instructions I think I need to

Remove 2+3 from the wiring centre as these go to the current thermostat which I shall reuse and supply with 12V to put the thermostat in the same place.

Terminal 3 on the nest to terminal 4 on the wiring centre for the call for heat, terminal 4 on the nest to terminal 8 on the wiring centre for the heating N/C, then 6 on the nest to 10 on the wiring centre for the hot water call for heat.

Commons linked out L - 2 - 5

Then just a general tidying up

The systems has a programmer

Drayton LP522 which will be removed

Drayton Thermostat

Cylinder Stat

Circulating pump for the central heating

2 Port mid position valve for hot water

 

[CBW]

You have some right, and some wrong. You don’t have a C plan, nor a 2 port mid position valve. You have a Y plan and it’s a 3 port mid position valve.

Your links on heat link are correct, and you can re-use the wires for the thermostat from the heat link. Everything else is copy over from the twin channel programmer, and you use the hot water off not heating off.

So L to L
N to N
Heating on which is terminal 4 (wiring center) but via the thermostat and what looks like terminal 9
Hot water on is terminal 6 (wc) but also what appears to come from programmer terminal 12
Hot water off is the grey, which is 7 via 8

 

[33-45-00]

Thanks yeah I was being a bit daft, I went for the easy option in the end and put the heat link where the programmer is and joined the thermostat wires through, capped of the neutral at the thermostat, as the wiring centre access is quite poor (hard to see from pictures but the pipe work for the shower pump are very close to the lid) then just used a constant voltage led driver to supply the thermostat from a lighting circuit

 

[CBW]

just used a constant voltage led driver to supply the thermostat from a lighting circuit

Not sure what this means.

 

[RandomGrinch]

Not sure what this means.

It sounds as if the OP has supplied the Nest thermostat with power from a 12V DC power supply, instead of using T1 and T2 from the Heat Link.
It should work ok, although there are some benefits to using T1 and T2, as the Nest can use these cables for signalling, rather than relying on wireless.

 

[CBW]

It sounds as if the OP has supplied the Nest thermostat with power from a 12V DC power supply, instead of using T1 and T2 from the Heat Link.
It should work ok, although there are some benefits to using T1 and T2, as the Nest can use these cables for signalling, rather than relying on wireless.

Ahh, wasn’t sure, as op referenced a lighting circuit

 

[RandomGrinch]

Ahh, wasn’t sure, as op referenced a lighting circuit

It's one way of doing it, I 'spose!

 

[33-45-00]

Don’t seen an issue, fitted a double pole fused spur for isolation purposes didn’t realise that the T1+T2 terminals also did communication

 

[RandomGrinch]

Don’t seen an issue,

Yup, no issues if it's done properly - it's just a bit unusual to see.
Most use T1 and T2, or the stand and a USB power supply.

didn’t realise that the T1+T2 terminals also did communication

Learn about Heat Link for Nest thermostats in Europe - Google Nest Help

Heat Link is a device that comes with your Google Nest thermostat in Europe. It connects to your heating system in order to start and stop your heating and is controlled by the Nest thermostat.

support.google.com