Things You'll Need
With a little care and preparation, it is easy to replace your old thermostat with a new digital Robertshaw thermostat. The Robertshaw non-programmable thermostat can work with gas or oil-fired boilers, gas or oil-forced air furnaces, single-stage heat pumps with no auxiliary heat, electric furnaces and single-stage air conditioners. This thermostat will not control multistage heat pumps or 110/220V baseboard electric heating systems. Installing the Robertshaw thermostat will take about 20 minutes and a minimum of tools and skill.
Remove the Old Thermostat
Turn off the power to the thermostat by shutting off the furnace, either at the breaker box or the power switch by the furnace.
Remove the front cover of the thermostat. Unscrew the front part of the thermostat from the wall plate.
Write down which colored wires go to which lettered terminals on the old thermostat.
Unscrew the wall plate from the wall and clip the colored wires with wire cutters. Bend the wires over the hole in the wall so that they do not fall down into the wall.
Installing the New Thermostat
Remove the front cover of the new Robertshaw thermostat by pushing on the spring clip on the bottom of the thermostat; this releases the wall plate from the front. Set aside the front of the thermostat.
Mount the wall plate so that the thermostat will cover the hole in the wall. Pull the wire through the back of the thermostat. Use a level on the top of the wall plate and install two screws through the screw holes in the wall plate.
Strip the insulation off the end of the wires by pinching the last 1/2 inch of the wire with your needle nose pliers and pulling. Separate the wires and line them up with the correct terminals. Refer to the note you made for the old thermostat. Wrap each wire around the screw on the correct terminal and tighten.
Set the selector switch on the inside of the front part of the thermostat to match your system. Set the switches to either a standard or a heat-pump system and the heat to either electric or gas. Consult your heating system's owner's manual if you are unsure of which type of system you have.
Line up the front of the thermostat with the wall plate and snap it in place. Restore power to the furnace and test the thermostat by pushing the up arrow on the thermostat until the temperature is higher than the temperature currently displayed on the thermostat and verifying that the heat comes on.