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Nest 3rd Gen Thermostat Battery?

lopiteaux
Community Member

‎03-09-2023 05:59 AM

Does the Nest 3rd Gen need to be plugged in via UBS/HVAC, or can it be used purely on battery?

 

@CoolingWizard - I saw you had discussed the battery on another (now closed) thread, so I was hoping to get your thoughts on this one...

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4 REPLIES 4

CoolingWizard
Platinum Product Expert
Platinum Product Expert

‎03-09-2023 04:39 PM

Lopiteaux,

It depends on how your air handler unit/furnace is configured.  If it has a modern Integrated Furnace Control Board, the changes are it will need a Common wire.  The way the Gen3 works is if you have wire attached to W and and a wire attached to Y, the thermostat can try to reach the COMMON side by traveling down the Y or W wire to the control relay coil.  The far side of that coil is where the COMMON is attached to.  Since the current draw of power to charge the Gen 3 thermostat is so low, it does not activate the Y (Cooling) or W (heat) relay.

I hope this helps you,

Ken, 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.
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lopiteaux
Community Member

‎03-13-2023 02:03 AM

Thanks Ken, appreciate it

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Jake
Community Specialist
Community Specialist
In response to lopiteaux

‎03-14-2023 11:23 AM

Hey there,

 

Thanks for the helpful reply Ken.

 

I wanted to follow up and see if I could be of any help. Please let me know if you have any questions from here, as I would be happy to take a closer look and assist you further. 

Best regards,
Jake

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lopiteaux
Community Member
In response to Jake

‎03-16-2023 12:33 PM - edited ‎03-16-2023 12:42 PM

Hi @Jake,

Please excuse my lack of knowledge on the subject.

I want to confirm whether the Nest 3rd Gen can be used without (a) wiring via wall (as my property does not have this option); or (b) plugged into mains via USB.

 

It's worth adding that I am connecting to a combi boiler (for hot water and heating), and that I have had the wireless receiver installed by a contractor/decorator. I have been using the thermostat plugged in to USB for about 2 weeks now, and I am not sure it is functioning correctly. The measured temperature does not move below 21.5 - 22.5 Celsius, even after the thermostat has been set to 28.0 Celsius for half a day, with the house becoming unbearably hot. I have tested it in every room, with no noticeable difference.

Is this user error, a result of the USB connection, or potentially a faulty device?

 

Cheers,

Carel.

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