How to Rewire a Lennox Electric Central Heating Unit

Shut off power to the thermostat by turning off the breaker on your home's circuit panel. If you have a fuse panel, remove the fuse for the thermostat.

Pull the cover off the thermostat that is mounted to the wall in the living area of your home. Note the color of the wires on the screw terminals by labeling each one with masking tape and a felt tip marker.

Loosen the screw terminals for each electrical wire with the Phillips screwdriver. Remove each of the wires.

Locate the screws that are used to secure the thermostat mounting plate on the wall. Loosen the screws and then pull the mounting plate off the wall. Ensure that the electrical wires do not retract into the wall or you will need to fish them out.

Position the mounting plate for the new thermostat on the wall. Mark the location of the screw holes on the wall with a pencil. Drill the screw holes into the wall using the power drill.

Insert a plastic screw anchor into each hole. Press on the anchors until they are flush with the wall. Run the electrical wires through the rear of the mounting plate.

Position the new thermostat mounting plate on the wall and align the screw holes. Insert screws into each of the mounting holes and then tighten them with the screwdriver.

Attach the electrical wires to the screw terminals. Use the location on the masking tape to put the wires on the correct screw terminals. Tighten the screws to secure the wires.

Insert a battery into the thermostat and then place the cover on the mounting plate. Turn on the breaker. Program the day and time into the thermostat. Turn on the thermostat and set the temperature.