If your home operates on a low voltage heating system, you should be able to locate the C-wire behind your current thermostat. You should be able to pop the cover off of your thermostat with ease.

How do you know if you have C wire?

Quote from the video:
Quote from Youtube video: Likely there is gonna be a fifth wire tucked into the wall I'm thinking that's going to be our C wire most likely because as you can see we have a green a yellow a white in a red.

How do I know if I have a blue wire or C wire?





Take your existing thermostat off the wall — it’s usually easy to do — and turn it over. You’ll see wires of many colors, and one of those might be blue. If so, look at the terminal to which it’s attached, and you should see the letter C. The blue wire, or C-wire, is known as the common wire.

What color is C wire?

Blue wires

Blue wires are also called “C” wires because they are the Common wire. C wires are necessary for any “smart” thermostat that needs to be connected to a power source 24/7, regardless of your heat pump type.

Do all thermostats have C wire?

A common wire (C-Wire) provides Wi-Fi thermostats continuous power by connecting it to a heating and cooling system (e.g. furnace). C-Wires are required on most Honeywell Wi-Fi thermostats, with the exception of the Smart Round Thermostat (formerly known as the Lyric Round).

Does Nest Thermostat E work without C wire?





Nest claims that you can use the Nest Thermostat without a C-wire. While this is true, it would be advisable to have a C-wire. A lot of Nest users have had problems when they use the thermostat without a C-wire. In the absence of a C wire, your thermostat battery charges itself by using the power from your HVAC system.

Where is the C wire on an old furnace?

Quote from the video:
Quote from Youtube video: The wire coming from outside from the condenser unit is only going to have two wires a red and a white looking like this. And those two are going to go to y. And c common on that terminal strip.

How do I know if my C wire is connected to my furnace?

If there is a wire connected to the C terminal at the HVAC control board:

  1. Note its color.
  2. Check if there are any wires tucked behind the back of the thermostat with the same color.
  3. If there is a matching wire, that should be your C wire.


Do older thermostats have a C wire?



As previously mentioned, older thermostats don’t necessarily need a C-wire to function. Yet, an unused C-wire may still be included in the bundle of thermostat wires tucked away in the wall. To check, simply turn off your system’s power and open the front plate of the thermostat to see the current wire connections.

How do I bypass the C wire on my thermostat?

Quote from the video:
Quote from Youtube video: Add a jumper wire between the Y and G. Terminals. If there's already wires attached just leave them be go ahead and push all the wires in. And close the backplate.

Can I use G wire for C wire?

Option #3: Use a G-Wire as a C-Wire



If there is no hidden C-wire, you can use a G-wire instead. However, you will not be able to use your fan independently when the heating or cooling isn’t running. Also, many HVAC systems are incompatible with this solution, including: HVAC systems using electric heat.

Can I install ecobee without C wire?



If you’re lacking a C wire and have at least four wires at your thermostat to work with (refer to this article if you only have two wires), you’ll want to install the Power Extender Kit (PEK).

Where does C wire go on Nest thermostat?

Quote from the video:
Quote from Youtube video: So here in my old wiring you can see that i have the y1. Gw1 rh and the c-space is missing that c wire. So here i definitely could use the c wire now that we have determined we need to add the c wire.

How do you wire a Nest thermostat without C wire?

Quote from the video:
Quote from Youtube video: For the common wire. So what you would do is go to your nest thermostat. Take off the G wire. Usually. It's going to be the green wire going to G. So you press on it you pull it out and before.

Do all smart thermostats require a C wire?

The good news is, some of the best smart thermostats do not require the power from the C wire to work. In fact, some of the best smart thermostats like the Google Nest Thermostat have no requirement for the C wire as they contain rechargeable batteries or other technology that removes the need for one.

How do I install nest power connector without C terminal?



Quote from the video:
Quote from Youtube video: So first i took the r cable on the power connector. Put it into a wire connector. And then i'm taking the r from the circuit board. And putting it in the wire.

Can I use a Nest Thermostat with only 2 wires?

Both the Nest E and Nest Gen 3 Thermostats can be installed with 2 wires. The procedure to install the Nest thermostat with 2 wires is the same for both thermostats.