How to Install a Honeywell Multistage Thermostat for a Furnace

Mount the thermostat subbase to a vertical or horizontal outlet box (if your furnace uses one) or to the wall near the furnace. Simply pull the thermostat wires from your heating system through the subbase wire opening, and secure the subbase to the wall or outlet box using the screws provided and a screwdriver.

Wire the subbase. First, completely power down the heating system. Once the system is off, connect the system wires to the system wire terminals on the left and right sides of the subbase, and tighten the screw terminals with a screwdriver.

Connect the stop brackets. After removing the back of the Honeywell thermostat, push the provided brass insert in the space just below the LED, or light-emitting diode, window, and place the two provided stop brackets into position between the "Heat" and "Cool" levers. Loosen the mounting screw, and push the Heat and Cool levers to their minimum and maximum desired settings, slide the stop brackets against each lever and tighten the mounting screw.

Mount the thermostat by attaching the thermostat to the subbase via the provided attachment screws. Tighten the screws, but be careful not to over-tighten them to avoid damage to the thermostat.