topic Re: nest thermostat connections in Nest Thermostats

nest thermostat connections

wjulaxer13 — Sat, 30 Oct 2021 21:34:07 GMT

i am looking at my current thermostat wires to determine if they are compatible with my new nest thermostat. The original thermostat has connections for R, W, G, Y, and W2. No C wire. The nest connection choices are R, W, G, Y, C, and O/B. No W2 connection. If I understand correctly, the W2 is an auxilliary connection and the O/B connection is for a heat pump. Does this mean that I can connect the W2 somewhere like the O/B connection (which doesnt make sense), do I need it at all, or does this require me to add a C connection. It is not at all clear to me. Any help will be appreciated. Thank you

Re: nest thermostat connections

wjulaxer13 — Sat, 30 Oct 2021 21:47:55 GMT

as i look at my wiring the original thermostat I noticed that all the wires match the colors that are associated with their designation in the charts. The W2 wire is blue which I would guess would mean it is the B wire. Does this help me to determine it goes into the O/B connector?

Re: nest thermostat connections

Hug3kids — Sun, 31 Oct 2021 14:19:58 GMT

Which thermostat do you have ? I believe both Y2 and W2 are for 2 stage cooling and 2 stage heating.

I think only the learning thermostats support 2 stage. I have a 3rd gen learning that has these. You may still need a "C" wire.

Re: nest thermostat connections

wjulaxer13 — Sun, 31 Oct 2021 15:26:40 GMT

The thermostat i am replacing is a Lennox X4147. I have attached the photos of the current thermostat and the new thermostat. Thank you.

John

Re: nest thermostat connections

Hug3kids — Mon, 01 Nov 2021 15:24:43 GMT

What kind of heat do you have ? It looks like you have a 2 stage heat system from looking at the wiring on your old Lenox thermostat. You may need to check with Nest support to see if there is a way to make it work, but think you may need the more expense thermostat to replace this one.

Re: nest thermostat connections

wjulaxer13 — Thu, 04 Nov 2021 01:57:12 GMT

I think what confuses me is that my current thermostat is also a 'smart' thermostat and as such must have a common wire to provide constant power. The only wire I see that could work would be the blue wire connected to the Aux port. Blue is used in common port wiring as well but i didnt think using the aux port would provide continuous current to the thermostat.

Re: nest thermostat connections

Hug3kids — Thu, 04 Nov 2021 14:11:41 GMT

probably not. Do you know what the aux port was connected to on your old thermostat ? Do you have a humidfier, zone damper or other device that it could be controlling ?

Re: nest thermostat connections

wjulaxer13 — Thu, 04 Nov 2021 17:49:57 GMT

I hadn't thought of that but there is a humidifier on the furnace. Good catch. I was under the impression that smart thermostats used a common wire for its continuous current. Apparently not.

Re: nest thermostat connections

Jake — Thu, 13 Jan 2022 19:39:49 GMT

Hey all,

Sorry for the late reply. I wanted to follow up and ensure you are 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: nest thermostat connections

Jake — Tue, 18 Jan 2022 21:51:43 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: nest thermostat connections

Jake — Wed, 19 Jan 2022 18:19:30 GMT

Hey all,

It has been a few days since the last reply, and I am going to lock the thread at this time. If you have any questions, please feel free to create a new post.

Best regards,
Jake