Smart Thermostat Brain Teaser

beaker

Hi all,

The more research I do (and I've done loads), the more I think our setup is unusual - a combi gas boiler with 3 zones. I found the attached wiring diagram (on the system) and I took a photo of the thermostat wiring. The boiler is an Immergas Victrex and there is a Honeywell CMT907A thermostat in each zone.

I would really appreciate some advice on how I could replace these thermostats with something like Nest or Hive. Thanks.

DGOBS

A picture of your time clock would be helpful.

beaker

Thanks for your help.

Is it possible that there is no time clock or that it has been removed? (Even though I see "T/C" in the wiring diagram)

The box of wires (see photo) has two wires exiting at the bottom left that are labelled "Time Clock 1" and "Time Clock 2". Those wires disappear behind a wall that has a fuse panel and a blank panel (see photo). I can't find a time clock anywhere.

Could there have been a time clock in the original system (perhaps with dumb thermostats) that was then removed when the programmable thermostats were put in? (We have just moved in so I don't know the history)

DGOBS

Ok, your system would have to have some re-wiring done, to revert from programmable room stats back to a standard s-plan controlling the 3 zones, and if for example you want Hive, you would hen require 3x receivers and 3xthermostats to control all your zones.

beaker

Thanks.

So for Hive, would that be one Heating Thermostat and two Additional Thermostats?

Is the only difference that the Heating Thermostat includes the hub?

Would 3 Nests with 3 heat links also be an option?

Would you recommend Hive or Nest?

DGOBS

I'm a Hive guy, so you'd have to ask elsewhere for nest mate.

Yes for heating thermostat (two additional Thermostats, with single channel receivers)