Add a C Wire Adapter

Installing your new WiFi thermostat can be a challenge if you don't have enough wires in your wall and can't run new ones from your system. In such cases, adding a C-Wire Adapter can be the best solution.

[@TrishHolmes-l8w]

This is a great tutorial. I followed it and was able to get my wifi thermostat working without a C wire even after our honeywell tech and electrician could not do so. Thank you!

[@marvellstarks2434]

You should of explained the k wire a little better when you hooked up the adapter. You gonna confuse some people.

[@horacioacosta6232]

Can this adapter be use for non-honeywell thermostats? Nest?
My ac unit looks like a rats nest with 4 to 6 wires of each color. I just want to use the thermostat without having to replace the batteries every few days.

[@ResideoSupport]

Hi Horacio, thank you for reaching out to us. This C-Wire adapter has not been tested with other brands. We recommend you reaching out to the manufacturer of your thermostat for recommendations. -Maria

[@jontorr2860]

Great video!

[@pricedout]

Does this prevent the use of the fan alone?

[@Steve_Edberg]

I was kind of hoping it ENABLES, not prevents the use of fan alone mode.

[@Steve_Edberg]

How does the K wire perform both the fan and the cool function?? I can understand how you could get three functions (fan, cool and heat) using two wires (K and W) with Boolean logic, but two functions on one wire like you say is a mystery. Do the thermostat change the voltage or frequency to the C-wire adapter to signal which output wire (Y or G) to turn on?? I'm just trying to wrap my head around how this works. Thank you.

[@ResideoSupport]

Hi Steve, we thank you for reaching out and sharing your concerns with us. The C-Wire adapter handles the internal connection to provide both energy and system control. If further questions arise, feel free to communicate with us via Facebook Honeywell Home or at 1-800-468-1502. -Charlie

[@Steve_Edberg]

@@ResideoSupport so does the one wire support both the fan and cool function independently?? I don't want any trade secrets from you on how the device operates, I'm just looking for assurance that this device can perform the task of two wires using just one wire. As long as I have the ability to control my furnace fan alone without having to turn the A/C on then I don't care how it does it.

[@ResideoSupport]

Hello Steve! Thank you for contacting us. Yes, the K label in the C Wire Adapter can control the Fan and the compressor independently. It will provide you two independent wires that you can connect to fan and compressor separately. -Alex

[@Steve_Edberg]

@@ResideoSupport excellent. Thank you Alex. That is all I needed to know. Hope you have a great afternoon. 😊

[@ResideoSupport]

Glad to help, Steve! Have a great day! -Alex

[@Mctoasty302]

I just bought one of these online just to realize they are not compatible with heat only systems (according to the packaging). 😢

[@ResideoSupport]

Hi, thank you for reaching out. If the heating system has only 2 wires (R-W) and there is no C terminal at the board the only way to supply the Common/C wire would be to use an external 24V transformer wires to the RC and C terminals of the thermostat. -Cesar

[@hvacworkshop4791]

Only good for some Honeywell