How to Hook Up a Lennox Thermostat

Ensure the circuit breaker for the furnace is in the "Off" position. It should likely still be off from when the previous thermostat was removed.

Separate and inspect the thermostat wires protruding from the wall. Each one should have approximately 1/4-inch of insulation removed from the end. If not, use your wire stripper to remove 1/4-inch of insulation from each wire in question.

Pull the wires through the slot on the thermostat's base. Place a level on the base and attach the base to the wall with screws. If screwing into drywall, utilize plastic anchors to prevent the screws from pulling out.

Insert the red wire into the "R" terminal and tighten the screw. Insert the green wire into the "G" terminal, yellow wire into the "Y" terminal, white wire into the "W" terminal and tighten all their corresponding screws. Push the excess wire back into the wall cavity.

Push the thermostat on to its base and it will snap into place.

Turn on the circuit breaker to the furnace. Familiarize yourself with your specific thermostat model's operation instructions.

Test the thermostat. Set the thermostat to "Heat" mode and raise the temperature to a set point higher than the room's temperature. The furnace should fire up and begin to heat your home. If it's summertime, test out cooling by setting it in "Cool" mode and set the temperature set point lower than the room's temperature.

Adjust the thermostat to your desired comfort level.