Replaceing BGWR1 with Nest 3rd Gen

[Bd250]

Hi All,

I thought my query had been answered before, but when I took the cover off the BG WR1 (Drayton Digistat RF) the wiring configuration wasn’t quite as I expected. My system is a Worcester Greenstar 30si Combi for both water and heat.

The mains power comes through an MCB and into the WR1, (L, N, Earth) [Grey 3 core]
The cable from the boiler comes into L, N, 3 and Earth [white 5 core]
The cable to the programmer goes from L, N, 1 and earth. [grey, painted 5 core]

I had planned to wire L, N and earth as they were for the mains and boiler, channel 3 on the WR 1 to channel 3 in the Nest (call for heat) but unsure what would then go in terminal 1 (common)?

 

[stem]

The Drayton Digistat receiver wiring is:

It's just a matter of moving the wires from the Digistat to the Nest Heat link terminals that have exactly the same function. So:

Wires in Digistat N = Heat link N

Wires in Digistat L = Heat link L

Wire in Digistat 1 'Common' = Heat link 2 'Common'

Wire in Digistat 3 'Call for Heat' = Heat link 3 'Call for Heat'.

You may have to terminate the Neutrals and Lives in separate terminals before taking a single wire for each to the Heat link, it will be difficult to get 3 wires in one Heat link terminal.