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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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What connections on my Lennox SLP98UHV do I use on my Nest

Customer Question

what connections on my Lennox SLP98UHV do I use on my Nest Thermostat
Submitted: 2 months ago.
Category: HVAC
Expert:  BillyHvac replied 2 months ago.

This depends on accessories or add ons.

What wires/terminals are utilized on the current thermostat?

Customer: replied 2 months ago.
I ran seven wires- origignal threo had 4 wires, The lennox unit has a four wire coneccention, then a panel with eight connection, is there a dip switch that needs to be flipped for the larger board to work
Expert:  BillyHvac replied 2 months ago.

was the previous thermostat a Icomfort with number terminals instead of letters?

Customer: replied 2 months ago.
R +1 -1 C
Expert:  BillyHvac replied 2 months ago.

Ok your furnace came as a package to operate at the highest efficiency possible.

Before we proceed, are you aware the changing to the Nest will lower your efficiency?

Customer: replied 2 months ago.
how is that possible
Expert:  BillyHvac replied 2 months ago.

Because the I Comfort is a communicating system that talks back and forth to a 1/10th of a degree.

It automatically adjust run times, blower speeds and uses an algorithm to make the furnace run as efficient as possible.

Basically this I Comfort is a package to talk continously as to what is going on, how fast the unit is heating/cooling and when it should shift gears.

The Nest is a simple on/off thermostat. It can run schedules and run times but does not "converse" with the system as the I Comfort.

I do not talk folks out of this change..I just warn you in case increased efficiency was your goal.