Nest Thermostat for Oil System Boiler

[jharrison]

Hi Forum

Im wanting to replace my Drayton timer with a Nest Thermostat. I have wired a few of these before, but hadnt seen this wiring setup before (and yes I know the earths arent connected, I started taking them off before I noticed the wiring setup) There is an additional Neutral connection thats coming from the wiring thats controlling the valves. Any idea where that would wire into in a Nest Gen 3?

 

[CBW]

It’s unlikely the neutral will “control” the valves, as they’re usually controlled by a thermostat. The additional neutral is likely to be for a room thermostat.

 

[ianmcd]

yes into the Neutral

 

[ericmark]

The terminals in the heat link are small, so rather than replace the wiring centre likely better to mount heat link next to it and connect into it.

One you know which motorised valve is CH and which is DHW you can likely using the motorised valve colours work out which wires feed the existing thermostat, then to be sure test wires, before reusing them for the 12 volt DC supply to the display. It is the display which measures the temperature, and has the PIR to detect if the home is occupied, and is used to set the system, I would have called it the thermostat, but Nest call it the display.