Connect Nest Learning Thermostat: 3rd Gen with Lennox SLP98UH

This post covers the steps I took to setup my Nest 3rd Generation Thermostat with my Lennox SLP98UH or SLP98UHV furnace. My furnace was originally connect to the Lennox iComfort 1st Gen Thermostat.

Overview of Steps:

1.     Turn the AC & Furnace off at the circuit breaker.
2.     Take the furnace cover off.
3.     Unscrew the 2 screws holding the circuit cover on.
4.     Re-wire the wires from iComfort to standard R, Y1, W1, and G.
5.     Setup the Nest Thermostat.

Step 1-3 are simple so I'll start with details for Step 4

Step 4 Details

At my furnace the 4 wires connected to a special terminal designed for integration with the iComfort thermostat:

I took the Red, Green, Blue, and White wires and re-wired them to the appropriate terminals: Red -> R (Power), Blue -> Y1 (Cool), White -> W1 (Heat), Green ->  G (Fan) as shown below:

Step 5 Details
At my current thermostat I had the 4 wires: Red->R, Green->i+, Blue->i-, White->C:

To hook up those wires to the Nest, I used the stickers to mark the wires: Red wire -> Rh, White wire -> W1, Green wire -> G, Blue wire -> Y1. Then I hooked those wires up to the nest back bracket:

Then I put the thermostat on. After I turned the power back on at the breaker for Furnace and A/C, I entered my WiFi information (I chose my 2.4 GHz signal). The Nest downloaded a firmware update and then I completed the setup steps displayed on the Nest.

Here's the final picture of the thermostat installed!

I hope this post helps someone else setup their Nest thermostat quickly! !-- Scripts Start -->

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