Lennox iComfort to Nest

[KDezIII]

Trying to understand if I can use the Nest Thermostat. From what I can see, I can but I jus want to make sure that I'm correct.

I am slightly confused with that jumper, ACC2 wire, that Orange wire which seems to not be connected to anything and the Black wire being cut... Not sure what to think of that.

I have 2 thermostats, 1 in the living room and 1 in the Master Bedroom, I assume the connections are the exact same. These images are from the Living Room thermostat (if that matters).

But anywho, just trying to figure out it if this would be compatible with the Nest? How would the connections be as well?

[EdwardT]

Hi KDezIII,

Thanks for reaching out. The ACC2 wire and the jumper is possibly proprietary to your current thermostat. Could you tell us the make and model of your current thermostat so we could further investigate?

Looking forward to your response.

Thanks,

Edward

[KDezIII]

Hello Edward, 

Yes, the Make and Model of my thermostat is the Lennox iComfort M30. Thermostat Control Model Number is 105144-01.

I have also noticed that the "wire" connection is not the same for my Master Bedroom Thermostat. It's using the same type of Thermostat, but the wiring is indeed different. Meaning some of the wires connected for the Living Room Thermostat, aren't used/connected for the Master Bedroom Thermostat.

Also, to note. I personally hate this Thermostat and its entire UI. I'm planning/thinking about purchasing the Nest 3rd Gen Thermostats and installing those to replace the Lennox Thermostat.

[kewalarun]

Hi, did you get a response on this or figured out how to connect these wires?

I have the exact same issue, I have one unit which is controlled by two Lennox M30 thermostats. The one in my Bed Room has 5 wires only i.e. R, Y1, W1, G and C, the living room thermostat has all these wires with additional Orange wire connected to ACC2. I have two questions:

1. Where shall I connect the R wire on M30 to Nest, as the Nest thermostat has Rh and Rc?

2. Where shall I connect the Orange wire which is connected to the ACC2 on M30 thermostat?

Any help would be greatly appreciated.

[KDezIII]

Hey! I have not gotten any additional help yet. 
I'm planning on getting an electrician to come to the house and check to see if the switch is doable. If so, will just have him do the conversion. 

[kewalarun · Accepted solution]

So, I got some help and they suggested 

The wiring should be like W1 to W1, Y1 to Y1, G to G, C to C and R to RH for both the thermostats.

We should cap the Orange wire ACC2 while installing the Nest Thermostat.

I installed two Nest Gen3 thermostats and replaced my iComfort. This is working well right, I have not tested the heating yet as the temperature is over 90 these days in Dallas. But the cooling works just fine. 

[KDezIII]

Appreciate the response! 

Could you elaborate on the Orange Wire? Are you saying disconnect it, cap it and push it in the back of the wall?

My master has the same wires connected but has a Jumper from ACC1 to R2.

My living room has all the above wires and jumper. But also has a brown wire connected to ACC2.

Ironically, I'm also in Dallas hah. Small world!

[kewalarun]

My living room thermostat had Orange wire connected to the ACC2, I just capped and pushed it back to the wall.

I have exact same setup as of yours, i guess the only difference is the orange and brown wire, which anyways connects to the same ACC2. I guess just cap the brown wire and push it out into the wall, and connect all other wires as mentioned and you would be good.

Where in Dallas, I am in the Little Elm area near Frisco?

[KDezIII]

Will try this out and see how it goes! Thanks.

I'm in McKinney.

[kewalarun]

Try that and let me know if you face any problems.

[KDezIII]

So I had an electrician come to the house today to rewire the thermostat! This was the way he wired it. Basically the same way you said but I see that the only difference is that he wired R to Rc.

[kewalarun]

I exactly did the same way as your electrician, not sure if forgot to mention that in my earlier replies.

Nest support team asked me to do connect R to Rh , but I connected R to Rc based on my understanding of Rc and Rh. I hope it is working for you now.

[MelbaDT]

Hey folks, 

Sorry for the delay here but thanks for keeping the thread updated on what you've both done to have your devices working with your HVAC system. Hats off to both of you for a job well done. 

Cheers, 

Melba

[MelbaDT]

Hey there, 

We haven't heard from you in a while so we'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the Community.

Best, 

Melba