# Convert Carrier thermostats to Nest



## flyerii (Aug 15, 2014)

I have a Carrier system in my home, with 2 remote sensors. 1 of these is the "main thermostat" and the other is a remote sensor. These go to a central Carrier control panel, which goes to the HVAC system, with traditional wiring (Y, C, G, Rh, W, etc.).

The sensors have the following:
- V+
- VG
- RS-
- RS+

From reading forums, it appears as if this is the configuration:
- V+: power
- VG: common
- RS-: remote sensor negative
- RS+: remote sensor positive

I know that Carrier uses a proprietary protocol, but am trying to figure out whether I can get a traditionally wired thermostat to work with this Carrier configuration. 

I am tempted to try the following:
- V+ --> Rh
- VG --> C 
- RS- --> Y
- RS+ --> W

Not sure if this will work or is prudent. 

Also, my current configuration allows me to turn the fan on & off, but in this 4 wire system, I don't have anything that will go to "G". I'm fine losing this functionality, but not sure if this will cause other issues.

Can someone please advise?


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## gregzoll (Dec 25, 2006)

Stick with the Carrier. You will not be able to use the Nest, due to having the remote sensor for your current unit. There are other thermostats that will work with your setup.

What is the model of the Carrier thermostat that you have?


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## flyerii (Aug 15, 2014)

I have a Comfort Zone (ZoneCC 2)and a Smart Sensor II.


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## HVACTECH96 (Oct 16, 2012)

The zone system you have is not compatable with any other type of aftermarket t- stats.The interface(main stat) and sensors are a comunicating type system.It does not use 24vac to control equipment.The system uses DC signals between interface and zone board.


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## flyerii (Aug 15, 2014)

Having done more homework, it looks like I would need to switch out my control board if I want to get WiFi capabilities, which I'm willing to do. Any recommendations? 

Here is a picture of my current board:


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## gregzoll (Dec 25, 2006)

Contact your local Carrier dealer. Carrier carries Wifi Thermostats. http://www.carrier.com/homecomfort/en/us/products/controls-and-thermostats/


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## flyerii (Aug 15, 2014)

I did. They claimed that the ComfortZone II is not compatible with anything Wifi & that they need to swap out the control board.


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## gregzoll (Dec 25, 2006)

flyerii said:


> I did. They claimed that the ComfortZone II is not compatible with anything Wifi & that they need to swap out the control board.


That is correct. You have no other choice with your setup.


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## flyerii (Aug 15, 2014)

Does anyone have a recommendation for a different board for me? I'm trying to shift from Carrier's ComfortZone II with a user interface + 1 smart sensor to a standard wired thermostat. So, what I think I need is a board which has the following characteristics:

- Support for 2 zones
- Support for 2 dampeners (with wiring for open, close, common)
- Leaving Air Temp sensor


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## HVACTECH96 (Oct 16, 2012)

any zone first (formally trol a temp) will work.zone board can use any brand of stat


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## flyerii (Aug 15, 2014)

I just ordered a MMZ3 (control panel) and a ZPS (sensor) from zonefirst.com. They were very helpful going through everything on the phone. Will update this thread on whether this works out or not.


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## jcg17 (Oct 16, 2017)

How did this turn out? I'm in a similar predicament so I'm curious if you changed out the control panel. Thanks!


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