Replace Lennox iComfort TouchscreenThermo 13H14 with Google Nest Learning Thermostat

[scworx]

How to replace existing Lennox iComfort TouchscreenThermo 13H14 with Google Nest Learning Thermostat 4th Gen.  This has six wires.

Lennox Thermostat backplate Wires: Y2 = Orange / C=Blue / G=Brown / W=White / Y1=Yellow / R=Red

Can I just match up the letr designations over to the Nest backplate-  

Where does Red wire go on Nest ?  Rc or Rh

FROM MANUAL -

LENNOX TERMINAL DESIGNATIONS Tc - Outdoor Temp. Sensor Connection 1 (Opt.) To - Outdoor Temp. Sensor Connection 2 (Opt.) H - Humidification relay (to Humidifier) D - Dehumidification relay (to DS terminal) W2 - Second-stage heating (non-heat pump) or 4th stage (heat pump) Y2 - Second-stage heating or cooling O - Cool active reversing valve B - Heat active reversing valve C - Common 24VAC G - Fan relay W1 - First-stage heating (non-heat pump or emergency heat) or third-stage heating (heat pump) Y1 - First-stage heating or cooling R - 24VAC power

[Patrick_Caezza]

@scworx 

Post a picture of the current thermostat's wiring here

[scworx]

[scworx]

Dont know how to tag @Patrick_Caezza

[scworx]

This is for the ComfortSense® 7500 (13H14)

https://www.lennox.com/lib/legacy-res/pdfs/manuals/cs7500_userguide.pdf

[Patrick_Caezza]

@scworx 

Thanks for the reply.

Give this wiring a try.

Orange - Y2 to Y2

Blue - C to C

Gray - G to G

White - W1 to W1

Yellow - Y1 to Y1

Red - R to Rc

[AustinWood]

In the Google Nest Community thread about replacing a Lennox iComfort Touchscreen Thermo 13H14 with a Google Nest Learning Thermostat (4th Gen), the original poster asked how to connect the six-wire Lennox thermostat to the Nest and specifically where to put the red wire (Rc or Rh), and a community expert asked them to post a photo of the existing wiring so they can guide the correct Nest terminal mapping but no full wiring solution was yet provided at the time of the latest replies.

[scworx]

@Patrick_Caezza 

Success!  After reading more about Red can use Rh or Rc, (Rh traditionally used) Orange wire used that for 2nd cooling, and I would not fry my board, I thought I'd give it a try.  I transferred over the letter/wire designations to the Nest backplate, matching the OLD Lennox back plate.  Turned the power back on the furnace and everything worked.   Sweet!!

Followed  Y2=Orange / C=Blue / G=Brown / W=White / Y1=Yellow / Rh=RedGoogle Nest Learning 4th gen Base Plate

Nest menu -Equipment

Nest menu-Equipment testing

Senses all equipment

[scworx]

Thank you all for your help- Thanks Patrick for your help!

Posted all pics for others to have success!!

Best Regards,

Micha

[carlbidwell]

Based on the wires you listed (R, C, G, Y1, Y2, W), this looks like a conventional 2H/2C system, so your Google Nest Learning Thermostat should connect as follows: Red → Rc (Nest internally bridges Rc/Rh), Blue → C, Brown → G, Yellow → Y1, Orange → Y2, and White → W1. Just make sure at the furnace control board the same labels match, since some Lennox iComfort systems are communicating and not directly compatible without rewiring. This related thread covers Lennox-to-Nest compatibility considerations: https://www.googlenestcommunity.com/t5/Nest-Thermostats/visit-Lennox-iComfort-thermostat-replacement-options/m-p/601234