topic Re: Is my wiring compatible with a nest thermostat? in Nest Thermostats

Is my wiring compatible with a nest thermostat?

aeisenberg — Sat, 23 Oct 2021 17:35:33 GMT

I have 4 wires going into my current thermostat: R, i+, i-, C. Is this compatible with a nest?

There is also a sticky note that says:

"Caution: 24 VAC Low Voltage Wiring only"

Is it possible to use this for a nest and what is the wiring configuration? Thanks.

Re: Is my wiring compatible with a nest thermostat?

Jimmyd — Sun, 14 Nov 2021 12:31:30 GMT

I have the same issue. Have you found a solution

Re: Is my wiring compatible with a nest thermostat?

aeisenberg — Sun, 14 Nov 2021 16:12:23 GMT

Yes. After a lot of research, and a consultation with an HVAC expert, I was able to rewire to install the nest.

The i+, i- wires are specific to lennox furnaces and iComfort thermostats. When an iComfort thermostat is used with a lennox furnace, there are more advanced features of the furnace that can be used, such as turning on at partial power and better timing of the power of the furnace. Moving to a nest, you lose those advanced features of the thermostat.

I hired an HVAC specialist to activate both the normal wires and the lennox-specific wires so that I could choose which kind of thermostat to use. In the end, I chose to go with a nest for several reasons:

The iComfort thermostats are something like $600 CAD and the nest is only $180 CAD
I wanted to add sensors to different rooms in the house to keep track of the heat in multiple locations
I trust Google's online security and safety more than I do lennox. I don't want anyone hacking into my wifi thermostat

That being said, I was on the edge of deciding to go with an iComfort because it does make better use of the furnace.

Here's a photo of my furnace's circuit board. Notice that there are two connection areas for wiring. One for the i+. i- and the other for "normal" wiring.

Oops...I don't seem to have access to upload images to this forum. You will have to use your imagination. 🙂

Re: Is my wiring compatible with a nest thermostat?

Jake — Wed, 08 Dec 2021 20:45:03 GMT

Hey all,

Sorry for the late reply. I wanted to follow up and ensure everyone is good to go. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

Best regards,
Jake

Re: Is my wiring compatible with a nest thermostat?

Jake — Fri, 10 Dec 2021 18:54:47 GMT

Hey all,

I want to ensure you are good to go, and everything is working properly. Please let me know if you are still having trouble, as I will be locking the thread in 24 hours due to inactivity.

Best regards,
Jake

Re: Is my wiring compatible with a nest thermostat?

rhammer — Sun, 12 Dec 2021 05:20:50 GMT

Do you know specifically how the HVAC unit was rewired? I have the same problem and would like to do it myself to use a Nest.

Re: Is my wiring compatible with a nest thermostat?

aeisenberg — Sun, 12 Dec 2021 06:06:11 GMT

Do you have a Lennox gas furnace with an iComfort thermostat? That's all I can speak to. This is how the wiring on the furnace side was hooked up. Notice that one side uses the i+/- and the other side uses the standard wiring. It's the standard wiring that the nest uses.

https://photos.app.goo.gl/J8A7MpfBh7o56wZs9

Re: Is my wiring compatible with a nest thermostat?

rhammer — Wed, 15 Dec 2021 00:28:15 GMT

Perfect! That's exactly what I was looking for! So, you're not using the 4 wires on the left side (i+/-) of the furnace motherboard at the Nest thermostat. just the 3 wires on the right, correct? They're just hanging disconnected?

Re: Is my wiring compatible with a nest thermostat?

aeisenberg — Wed, 15 Dec 2021 03:44:42 GMT

@rhammer wrote:
Perfect! That's exactly what I was looking for! So, you're not using the 4 wires on the left side (i+/-) of the furnace motherboard at the Nest thermostat. just the 3 wires on the right, correct? They're just hanging disconnected?

That's correct. I kept them available, but disconnected on my wall upstairs just in case I ever decided to go back to using an iComfort, but I doubt I will.

Re: Is my wiring compatible with a nest thermostat?

chewpr01 — Thu, 16 Dec 2021 18:35:12 GMT

When I turn on the nest it states heater. Does the nest also control AC compressor thru this 3-wire configuration?

Re: Is my wiring compatible with a nest thermostat?

aeisenberg — Thu, 16 Dec 2021 19:50:17 GMT

I would think that if you want to hook up AC to the nest, you will need to include additional wires. We don't have AC, so I can't help you more than this.

Re: Is my wiring compatible with a nest thermostat?

rhammer — Thu, 16 Dec 2021 20:32:54 GMT

Perfect. Thanks again!

Re: Is my wiring compatible with a nest thermostat?

chewpr01 — Thu, 16 Dec 2021 21:46:15 GMT

Simply connect Y1 to Y1 on the nest in addition to those 3-wires to the right. That gets the AC going. Nest test works and all is well.

Re: Is my wiring compatible with a nest thermostat?

Pass1277 — Fri, 01 Apr 2022 23:10:07 GMT

I can get my heater working but when I hook my y1 wire to my nest and to my panel on the unit the ac acts like it will run, in that the indoor blower motor comes on but my compressor outsidedoesn't.

Re: Is my wiring compatible with a nest thermostat?

aeisenberg — Sun, 03 Apr 2022 19:51:01 GMT

My system doesn't have any AC, so I can't help you. You might need to get a professional to take a look.

Re: Is my wiring compatible with a nest thermostat?

esp91 — Wed, 11 May 2022 11:49:58 GMT

Were you ever able to figure this out? I am having the same issue.

Re: Is my wiring compatible with a nest thermostat?

ktmailserv — Sun, 07 Aug 2022 04:04:22 GMT

Any update on how you solved this? Any pics of your wiring ?

Re: Is my wiring compatible with a nest thermostat?

PerryT — Thu, 08 Sep 2022 16:21:17 GMT

Could you be more specific about the advanced features on the Google Nest Learning Thermostat that will continue to function when installed on the Lennox iComfort, and which Google features won't?

Re: Is my wiring compatible with a nest thermostat?

PerryT — Thu, 08 Sep 2022 17:23:21 GMT

"Simply" means moving the two middle wires on the left (black and white) to the Y2 and Y1 stations on the right?

Re: Is my wiring compatible with a nest thermostat?

aeisenberg — Thu, 08 Sep 2022 18:40:56 GMT

I don't know the specifics, but I think the main features that iComfort has and Nest doesn't is the ability to turn the furnace on at a lower power. For the Nest, the furnace is either on or off. The iComfort can be on, but at a lower intensity. I can't be any more specific than that. Maybe someone else knows more.