How to Install an Electric Heater with Thermostat: The big picture
Does your home have a room or two that just don’t stay warm in cold weather? If you can’t adjust the central heating system to warm the room, consider adding an electric heater. You can conveniently mount electric heaters in walls, in floors (between joists), or along the baseboard.
While electric heat is more expensive than gas, the heaters and materials for installation are much less expensive. Keep in mind that these are for auxiliary heat, not the main source. We recommend that you put the heater on a separate setback thermostat that automatically turns it on when you’re home and using the room.
DIY Wall Mounted Electric Heater with Thermostat
In this article, we’ll show you how to hard-wire a heater, which means you have to run a separate circuit to the main panel. This is safer than using a plug-in portable heater, which can overload an existing circuit. We’ll show you how to size the heater, run a new, safe 240-volt circuit and install a programmable thermostat. We won’t show you how to hook the circuit into the main electrical panel. Hire a licensed electrician for that step.
Most homes have sufficient capacity for the new circuit in the service panel for an electric heater with thermostat. If you have circuit breakers, you’ll need two empty breaker spaces. A fuse box can be more difficult to read. Have the electrician you hire check your panel before you start the project and confirm the planned hookup. Be sure to apply for a local electrical permit so an inspector will check your work.
Electric heaters are sized by wattage. See “Sizing Your Heater,” to determine the right one for your space. For a heater up to 2,880 watts, run a cable with two 14-gauge wires and one ground wire (called 14-2 with ground); run 12-2 cable with ground to handle up to 3,840 watts.
Figure A: Typical Wiring Plan
This is a standard, simple plan for wiring an electric heater.
Find the easiest cable route: Locate the heater
Find a location for the heater and thermostat on the wall. Push about 12 in. of wire, such as a coat hanger, through the ceiling drywall directly above the heater and thermostat locations.