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Connect your blue C wire from the thermostat to where the white wire from the A/C joins in with the dark wire from the furnace There's a simple logic you can follow here, since you have an air conditioner. In just about all cases, the air conditioner's control wires must be connected to the Y and C wires in order for your air conditioner to work. As a ...


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For traditional Heat + Fan + AC systems, you need 4 for the system to work at all, and 5 if you want to support the C wire for smart 'stats. However when you get into heat pump and multistage systems, just throw an 8 in there - it's readily available and not that much more expensive. You're not going to get very many latté's with the cost savings from ...


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Add your C wire to the junction of the thin white wire and the fat blue wire We can follow a rather easy logic here, since you have air conditioning. We know for a fact that the cable going off to the air conditioner compressor must connect to the Y and C wires in order to work. Thus, since the yellow Y wire from the thermostat connects to the red wire ...


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If you're building a new building and having new HVAC installed, I would simply put 1/2" conduit in the wall and be done. That way, you let the installer run the wire they need. I don't know that I would do this without at least consulting an HVAC installer to see where they would put the unit and the air return (typically the thermostat is as near the ...


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I'd use 20/8 which is pretty standard today. That will cover anything up to a 2-stage heat pump system. I'm not sure how WiFi factors in here. An smart/electronic thermostat like a Nest does support WiFi but not between the HVAC unit and the thermostat.


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Based off the first picture, it looks like the blue wire fell out from the wirenut next to it with the black and white wires going into it. That should be the common side of the 24 volt transformer used for the AC, which is what you probably want to be using for C. Test to see if that all makes sense first rather than just connecting it. I'd rather not ...


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Attach it to the junction of the fat blue wire and the skinny red wire Since it appears like you have air conditioning, as the yellow wire from what looks to be your thermostat cable goes off to what looks like a connection to a white wire in a two-wire cable, likely running to the outdoor unit (compressor). Because of this, we can make a good guess that ...


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It's the grey wire in the thermostat wire bundle According to the wiring diagram posted for your furnace, the C wire should be the grey wire in the thermostat wiring area of your furnace. So, you should just be able to connect to that.


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Your setup is "upside down" Normally, 24VAC HVAC thermostats are set up to switch on the high side, connected between the ungrounded secondary terminal (R terminal) on the transformer and the actuator (gas valve, furnace control, zone valve, compressor contactor, fan relay, ...), with the other side of the actuator connected to the grounded secondary ...


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I also have the Lenox G12Q4-110 furnace (heating and cooling) system with a four conductor thermostat wire. I found the instructions posted here of tremendous value in confirming that I could update the thermostat to an ecobee3 lite using their five wire to four wire adapter that was included in the box. I was able to make all of the wiring connections, ...


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