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2 wire honeywell to Nest thermostat

Popster
Community Member

Hi I have an Honeywell thermostat I want to replace with a Nest. Is this compatible. Picture below. If so what are the best wire points. Please

image.jpg

 

 

1 Recommended Answer

great and thanks for your response and patience. Is this the best you are referring to. Google Nest Smart Programmable WiFi Thermostat - Snow White G4CVZ. I appreciate the help

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11 REPLIES 11

CoolingWizard
Platinum Product Expert
Platinum Product Expert

The Honeywell 900 series thermostats can operate between 24 to 230 V. So that thermostat can either be switching line voltage down to a furnace, or it can be simply operating at millivolts controlling a gas valve. It is not a conventional HVAC, where you would have 24 V AC coming in on our and being sent back on Y, W, G, O/B..  the only time I’ve ever seen these 900 series is over in Europe.

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner. If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

Hi thanks. This is a Honeywell CM907 thermostat. I should have mentioned it is for a gas boiler that runs my hydronic heating only no AC. Which is an Italian ‘Radiant’ brand. Im

located in Australia 

CoolingWizard
Platinum Product Expert
Platinum Product Expert

Here is a picture form the Honeywell Manual:

4BCF8205-FC56-4A6B-A6EC-3B02B7FB07FA.jpeg

Your hookup it probably Wiring a, above.

The AC Cooling Wizard 

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner. If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

Hi thanks I agree. It a simple on or off. Does  wiring  work with the Nest?, if yes what are the two letters I would wire them to on the nest?  Thanks 

CoolingWizard
Platinum Product Expert
Platinum Product Expert

You will need a basic Nest thermostat, the one that uses AA batteries.  The wire connections for your heating will be R and W.  

The AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner. If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

great and thanks for your response and patience. Is this the best you are referring to. Google Nest Smart Programmable WiFi Thermostat - Snow White G4CVZ. I appreciate the help

CoolingWizard
Platinum Product Expert
Platinum Product Expert

Yes indeed. The thermostat you have does not require a third wire for the power common.  

The AC Cooling Wizard

NestPro, Google Pro, Mechanical Engineer and HVAC service company owner. If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.

Patrick_Caezza
Platinum Product Expert
Platinum Product Expert

@Popster 

You didn't say what the thermostat is connected to, and there is a high probability that it is a 220-230Vac device that is incompatible with the none UK/Europe Nest thermostats.

Please verify the voltage at the A and B terminals.


To ensure that I see your reply, please tag me using @Patrick_Caezza

Hello there,

 

I wanted to ensure that everything was covered here.

 

Thanks for all your help with compatibility checking, @CoolingWizard and @Patrick_Caezza.

 

@Popster, I hope you've got the answer you're looking for. If you're still in need of assistance, feel free to let us know.

 

Best,

Mark

Jenelyn_O
Community Specialist
Community Specialist

Hi folks,

I wanted to follow up if you still need help. Please let me know if you’re still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

I appreciate your help, Mark.

Thanks,
Jenelyn

Jenelyn_O
Community Specialist
Community Specialist

Hi Popster,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.

Regards,
Jenelyn