Replacing High Voltage Thermostat with Nest

[BrennaBoy]

Hi All,

Hope I am posting this in the correct area.

I currently have a fixed wired Honeywell T6360B thermostat which I am looking to replace with the Nest.

The Honeywell thermostat is a high voltage 240V thermostat, but the nest is a 12V thermostat.

I just have a few wonderings at the moment...

1). Can I put something in the wall before redecorating and replacing thermostat to step the voltage down from 240V to 12V to then connect to the back of the nest.

2). I am assuming that as long as the voltage is step down, the new thermostat can be easily fitted as it would simply use the call for heat function providing the boiler is in "Always On" mode?

3). How does the call to heat function work with a fixed wired thermostat - is it just a signal wire to tell the boiler to switch on and off?

Any help and guidance would be very much appreciated.

Many thanks,

BrennaBoy.

 

[ban-all-sheds]

I currently have a fixed wired Honeywell T6360B thermostat which I am looking to replace with the Nest.

All that advertising is paying off.

The Honeywell thermostat is a high voltage 240V thermostat, but the nest is a 12V thermostat.

I thought it was 24V.

1). Can I put something in the wall before redecorating and replacing thermostat to step the voltage down from 240V to 12V to then connect to the back of the nest.

You'll need a 24V transformer. It may not be possible to bury it in the wall.

3). How does the call to heat function work with a fixed wired thermostat - is it just a signal wire to tell the boiler to switch on and off?

It varies - some boilers want volt-free contacts in the thermostat, some don't. How is yours wired? How many conductors run between the thermostat and the boiler?

But it's irrelevant, surely if you're having a Nest. You can wire it to the receiver by the boiler if you have wiring available, or use wireless.

Any help and guidance would be very much appreciated.

https://community.nest.com/welcome

//search.diynot.com/forum_sear...tbytime=0&author=&search=Search+Forum&stype=0

 

[Taylortwocities]

All of this has already been discussed in detail, on the plumbing forum. Helpfully it includes extracts from the NEST installation manual.
//www.diynot.com/forums/plumbing/nest-install-2-wire-replacing-existing-stat.398926/

NEST comes in two bits . The HEATLINK at the boiler end (230v) and the thermostat bit (24v). The HEATLINK has the capability to supply the 24v to the thermostat.

If you can't understand it then you'll need a NEST installer.

 

[winston1]

According to the above link the nest is 12 volt as the OP said.

 

[Taylortwocities]

Correct!

 

[AndyPRK]

I think the US ones are 24V ?

 

[ban-all-sheds]

I think that must be it. Isn't 24V signalling the norm for HVAC systems there?

 

[Alex123-4]

Hi BrennaBoy,
The UK version of the NEST comes with a HEATLINK which the Thermostat connects to via terminals T1 and T2. DONT WIRE ANY 110/240V to this Thermostat otherwise youll have an expensive paper weight to deal with.
My advice is if you are uncertain or do not understand the electrics then pay for a Professional to fit it for you then youll be 100% safe.

 

[Taylortwocities]

Alex, that topic was from nearly a year ago.
I would guess that he already knows, if he has wired it wrong

 

[Alex123-4]

Taylor duhhhhhhhhhhhhhhhhhhhhhhhhhhhh, haha never noticed the date!!!!