Choose a location with no drafts, hot or cold air from ducts, radiant heat from sun or appliances, or unheated areas like an outside wall behind the thermostat. Install the sub-base about 5 feet above the floor in an area with good air circulation at room temperature.
If you are replacing an existing thermostat, turn off the power at the furnace. Remove existing sub-base from the wall and label each wire color with the letter or number on the wiring terminal to avoid miswiring.
For a new installation, run cable to a hole where you plan to install the thermostat. Pull approximately 3 inches of wire through the opening. Color-coded 18-gauge thermostat cable is recommended. The cable should have one conductor for each wiring terminal.
Remove the thermostat from the sub-base. Mount the sub-base onto the wall. Screws and anchors are provided. With a pencil, mark the two mounting screw positions using the sub-base as a template. Drill the holes for the anchors using a 3/16 inch drill bit. Tap the anchors into the holes. Use plastic anchors if you are mounting to drywall. Thread wires through the opening of the sub-base and mount the sub-base with screws.
Disconnect power before wiring. Straight or conventional wraparound wiring connections are permitted and either is acceptable. Push extra wire back into the hole and seal the hole to prevent extra draft from affecting the thermostat.
Program the time and desired temperature into the thermostat. Install three AAA alkaline batteries into the thermostat to prevent program loss in the event of a power outage.