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C wire adapter

Surfermike
Community Member

Want to add a c wire adapter to my nest thermostat. Currently have a 2 wire heating system. One goes to W and the other to R. Where do the two adapter wires go ? I assume one in the C slot, but where does the second wire go?

 

 Thanks 

11 REPLIES 11

Houptee
Silver Product Expert
Silver Product Expert

Make sure you have a 24V AC adapter (Not 24V DC)  Look on the adapter to confirm the output voltage is AC.

Adapter wires go to Rc and C.

Existing Heating system existing wires go to Rh and W


Houptee -- NJ Master HVAC Licensed Contractor

I don’t have Rc and Rh only one R   . Can I put two wires into this one connection?

Cip54
Community Member

He's referring to the contacts in the Nest. So your R goes to Rh, W to W, One of your adapter wires on Rc the other on C (it doesn't matter which).

If you don't want to have an adapter wire running externally you should check out Fast stat common maker. Easy to wire if you have access to your furnace.

Houptee
Silver Product Expert
Silver Product Expert

The C wire adapter transformer wires go to Rc and C.

If the wires are not labeled it doesn't matter which one goes to Rc and C because there is actually no + and - in AC power, it is a sine wave that alternates, hence Alternating current AC.

Your old R wire goes to the Rh and the old W goes to W1


Houptee -- NJ Master HVAC Licensed Contractor

EdwardT
Community Specialist
Community Specialist

Hi folks,

 

@Houptee and Cip54, thanks for the help!

 

@Surfermike, how's it going with your Nest Thermostat? Still need our help?

 

Thanks,

Edward

Yes I do. I have the best with only 6 connection options on the thermostat. My C wire adapter has two wires, I understand that once goes into the C connection, but where does the second wire go? I only have one R connection that is currently being used for my heating unit. Thanks for your help 

Houptee
Silver Product Expert
Silver Product Expert

Put both your original Red wire, and one wire from the AC adapter together into the R on the Nest.

Here is a video how to do it.

https://www.youtube.com/watch?v=yi5kfn3bmEk&ab_channel=OneHourSmartHome


Houptee -- NJ Master HVAC Licensed Contractor

Cip54
Community Member

I just installed a "common maker" from fast-stat. Easy to install if you can access your furnace:

 

https://smile.amazon.com/Fast-STAT-Common-Maker-Popular-Thermostats/dp/B07G2NGFKH/ref=sr_1_1?crid=1Y...

Uses your 2 wires and doesn't need an external wall wart and unsightly wires...

EdwardT
Community Specialist
Community Specialist

Hi folks,

 

@Cip54 and Houptee, thanks for the help!

 

@Surfermike, how's it going with your Nest Thermostat? Were you able to check the links that Houptee and Cip54 provided? Let us know if you have other questions and we'd be glad to assist.

 

Thanks,

Edward

EdwardT
Community Specialist
Community Specialist

Hi Surfermike,

 

It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do. 

 

Thanks,

Edward

aatienza
Community Specialist
Community Specialist

Hi there,

 

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.
 

Thanks,

Archie