Because electric heat is one of the most expensive ways to heat your home, you can cut your heating bills significantly by installing a programmable thermostat, like this one, which automatically turns down the heat when it isn't needed. Make sure you buy a high-voltage thermostat designed for electric baseboard heat. Thermostats for electric-baseboard heaters operate at the same voltage as the heater -- usually 240 volts. Low-voltage thermostats designed for gas, oil, or heat pumps won't work and are extremely dangerous on a high-voltage system.
Line-voltage thermostats operate at either 120 or 240 volts and control gable vent fans, electric baseboard heaters, and similar appliances. Replacing them is different but no harder than replacing a furnace thermostat. There is one important -- and potentially dangerous -- difference between the two, however. A conventional low-voltage thermostat operates at 24 volts. An electric baseboard heater may operate at 240 volts. Always make sure the power is off when working on either type of thermostat, but be doubly cautious with a line-voltage thermostat.
What You Need
- Multimeter or circuit tester and continuity tester
- Line-voltage thermostat
- Wire nuts
Step 1: Remove Thermostat
Warning: Before you begin, turn off power to the circuit.
Take the cover off the thermostat and remove the screws that attach it to the junction box. Without touching any of the wires, lift the thermostat away from the box.
Step 2: Test Circuit
Make sure power is off. Place a circuit tester or multimeter across the ground wire and each of the other wires in turn to make sure there is no voltage flowing in the lines. If the ground wire is attached to a metal junction box, you can substitute the box for the ground wire when testing.
Step 3: Label and Disconnect Wires
Label the wires as you disconnect them. Mark which wires go to the terminals labeled "line" and which go to the ones labeled "load."
Step 4: Test the Thermostat
Attach one lead of a continuity tester to one "line" wire and the other lead to the "load" wire on the same side. Turn the dial from high to low. If the thermostat is good, the tester remains lit in both positions. Repeat on the other set. If the light goes out, replace the thermostat.
Step 5: Connect Wires
Connect the wires you labeled "line" to the load wires on the thermostat.
Connect the wires you labeled "load" to the load wires on the thermostat.
Step 6: Return Thermostat
Fold the wires into the box, attach the thermostat to the junction box, and reposition the cover.