How to install a room thermostat

Updated February 21, 2017

Installing a new room thermostat can make a heating system more efficient. New thermostats can be programmable or non-programmable. A programmable thermostat allows you to adjust the temperature throughout the day, keeping it lower when a room is empty. Replacing an old thermostat with a programmable one is an easy do-it-yourself project.

Remove the existing thermostat from the wall. Pull the cover plate off of the thermostat, exposing the wires and the mounting screws. Loosen the wire-clamping screws with the Phillips screwdriver. Wrap the wires around a pencil and secure them with electrical tape. Remove the mounting screws from the base plate of the thermostat.

Hold the new programmable thermostat's base plate against the wall. Line up the wire hole on the base plate with the wire hole on the wall. Level the mounting plate using the carpenter's level. Mark the screw-mounting holes with the pencil. Remove the base plate from the wall.

Drill a 5/16-inch hole at each mounting location that you marked with the pencil. Insert a wall anchor (included with the hardware) into each hole. Feed the pencil and wires through the mounting base plate. Thread the screws into the wall anchors to secure the mounting base plate to the wall.

Remove the electrical tape from the pencil to release the low-voltage wires. If the ends of the wires are damaged, cut them and strip the plastic from the ends with wire cutters. Follow the low-voltage wiring diagram supplied with the thermostat. Insert the proper wire into the proper connector. Tighten the clamping screw to secure each wire in place. Make sure that the copper inner wires do not touch each other. This will cause the thermostat to short out, which could damage the unit.

Attach the cover to the mounting plate after all of the wires are secure. Snap the cover plate securely into place. Turn on the programmable thermostat and install the backup battery. Run the thermostat through the heating cycle to ensure that the unit is wired correctly.

Program the thermostat. Periodically check the unit to make sure that it is operating properly.

Things You'll Need

  • Programmable thermostat
  • Phillips screwdriver
  • Electrical tape
  • Drill
  • 5/16-inch drill bit
  • Wire cutters
  • Wire stripper
  • Carpenter's level
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