Nest 3rd Generation old wall battery thermostat question

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WhooshDIY

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Sorry in advance long post plenty of questions

I managed, years ago to change my controller (kitchen) and thermostat (hall) and it all still works - I have heating and hot water tank, mid positon valve, hot water timed on kitchen controller, heating permanently on at controller and then programmed by the wall thermostat. The old one was just a twisty dial.

Quite familiar with the wiring in the airing cupboard junction box too as I've replace the mid valve more than once!

However
The wall thermostat is battery powered - Honeywell CM67 and all the instructions I've seen and googled refer to a wall thermostat with power.

I think I can cope with replacing the controller with the heat link and happy to have the nest on a stand with usb power - but, what do I do with the wall thermostat wiring?

And/Or can I leave the controller in situ and put the link elsewhere?
 
You could use the 2 wires behind thermostat to power the Nest thermostat, if you’re locating the heat link near the wiring center.
 
CBW said:
You could use the 2 wires behind thermostat to power the Nest thermostat, if you’re locating the heat link near the wiring center.
Click to expand...
There's no power to those wires behind the thermostat in the hall - the heat link could go where the controller inthe kitchen is.
 
ianmcd said:
just join COM and NO in a termonal strip and insulate and tuck away safely, or locate the two wires in the wiring centre , remove completely and replace with a permanent link
Click to expand...
Sounds easy enough, so then that's just on constant heat demand and conrtrolled by the heat link wired in at the controller? - and then I could just remove the Honeywell thermostat box and fix the hole or put a picture over it ;-)
 
WhooshDIY said:
There's no power to those wires behind the thermostat in the hall - the heat link could go where the controller inthe kitchen is.
Click to expand...

As CBW says you could locate the nest thermostat on the wall where the old thermostat was mounted.

If you can identify the two wires from the boiler that used to connect to the thermostat you can remove them and connect them to the Heatlink T1 and T2 terminals to provide low voltage power for the Nest.
 
CBW said:
So you have a wireless receiver?
Click to expand...
No, it's a Honeywell thermostat, connected to the wires where the old 26 year old twist dial themostat was, I think theres only calling wires and no power as the unit has batteries, the heating is on 24 hours on controller in kitchen
 
WhooshDIY said:
No, it's a Honeywell thermostat, connected to the wires where the old 26 year old twist dial themostat was, I think theres only calling wires and no power as the unit has batteries, the heating is on 24 hours on controller in kitchen
Click to expand...
Right so, you have a live in and a switched at possibly mains voltage (230/240vac), or even low voltage (24v) - Power.

If you were to connect these to T1 and T2 the heat link sends 12v down one wire
and back again completing the circuit, therefore having - power.
 
WhooshDIY said:
Sounds easy enough, so then that's just on constant heat demand and conrtrolled by the heat link wired in at the controller? - and then I could just remove the Honeywell thermostat box and fix the hole or put a picture over it ;)
Click to expand...
yes or as the others have said , if you want the nest there you can use the existing wires to power the stat from the heatlink
 
ianmcd said:
yes or as the others have said , if you want the nest there you can use the existing wires to power the stat from the heatlink
Click to expand...

well - that's just confused and amazed me no end - so, if the heatlink will be in the kitchen replacing the current controller Drayton Lifestile LP522, then I can get power from there to the Thermostat in the hall ? Bonus. Might get a stand for USB power in the living room too then . . .
Though I don't think there's a live in to the hall thermostat - confused am I.
Might just get a man in ;-)
 
you can power the nest from the two 12v connections from the heatlink, to the nest thermosta, DO NOT USE A LIVE, but you also need an earth, the nest is then permanently fixed where it is, if you want to use the usb to power the nest , then you can use the stand and move the nest around
 
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