Questions tagged [nest]

The Nest is a programmable, internet-enabled thermostat

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Why are the white and orange wires both connected to my thermostat's W terminal?

I wanted to get a programmable thermostat, but when I look at the wiring of the existing thermostat I’m not sure why the white and orange wires are both going to the W terminal. Other thermostat ...
anthonyjhd's user avatar
3 votes
3 answers
16k views

Do I have one or two 24V transformers in HVAC control circuit

I have two old thermostats (one for heating, the other for cooling) that I would like to replace with a single Nest E unit. I have central air and gas heating. Cooling thermostat has the following ...
John's user avatar
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Why is Thermostat Y wire connected to C terminal on furnace?

I have a Nest E thermostat, and like many others have lost wifi and getting low battery because I have no common wire connected. After looking at my old Lennnox 78ugf3-75-1 furnace, I noticed that my ...
DJ2904's user avatar
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Connecting Common Wire from thermostat to Air Handler

My apartment has a central heating/cooling HVAC system consisting of a gas-fired hot water heater which feeds hot water to a First Co air handler for heating, and a rooftop compressor which feeds ...
SSilk's user avatar
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1 answer
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No power coming from c terminal on furnace

I am trying to set up a nest. My system was a simple heat only R/W wire set up. I attached the green wire to the c terminal on my furnace, but no power is being fed from it, or at least the Nest is ...
AdamG's user avatar
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13k views

Adding a C Wire using a 24V AC Transformer to a 2 Wire Heating System for Nest

Continuation from Can I use any of my existing oil control terminals (TTFFAA) for a C wire? EDIT: Wanted to finally say this is SOLVED with help from @JPhi1618 (see conversation below). If you have a ...
Teuszie's user avatar
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Can I use this unused blue wire as my C wire for my new Nest thermostat?

I am a bit confused with my furnace wires. I did some research and watched a bunch of YouTube videos on how to install the Nest thermostat. I currently have a normal digital Honeywell thermostat. I ...
Sharikh Khan's user avatar
1 vote
1 answer
2k views

Add-A-Wire - COMMON / C Wire to a 3 Wire Thermostat

I am battling a Nest and losing at every turn. I have a 2 zone system and was able to install a Nest on the 1st floor by repurposing a wire as a COMMON wire. Unfortunately, the 2nd floor only has 3 ...
sagosto's user avatar
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1 vote
3 answers
14k views

Separate boiler and AC, to which does C wire connect for Nest thermostat

I have installed a Nest thermostat into a system with hot water heat and separate a/c system each with its own transformer. To run a C wire to gain constant power, does the wire connect to the boiler,...
mvwc1's user avatar
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1 vote
1 answer
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Is it possible to wire an electric radiant floor as a heat pump in my Nest thermostat?

I have a standard gas furnace, but recently installed an electric radiant floor in one room. I have a transformer at the electric floor and a regular low voltage thermostat wire to my Nest thermostat. ...
Sealander's user avatar
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Where to connect C wire if no C terminal

Hi wanting to connect Nest and want to install a C wire. HVAC only appears to have G,W,R so not sure where to connect C.
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Nest snow thermostat with a McLain PEG-45 boiler

I have a problem similar to the one in this question. My R wire from the thermostat to the G terminal on boiler and the W wire from the thermostat to the Y terminal on the boiler. The picture is a bit ...
Frank Weber's user avatar