Adding an electric baseboard or wall heater can be a cost-effective way to bring heat to a cold spot or an area that gets only occasional use.
Plan 10 watts of heater capacity per square foot of room area. Check local codes for circuit requirements; some municipalities require a dedicated circuit protected by a 20-amp double breaker. In some cases, you can add heaters to existing 120-volt circuits. Confirm that the circuit voltage matches the heater voltage.
Place heaters on outside walls below windows. Never locate a heater beneath a receptacle. Follow the manufacturer's recommendations for placing furniture and draperies near the unit. In general, baseboard units are best for supplemental heat; blower-heaters are best for intense heat of short duration.
About 3 hours to run cable and install a baseboard heater and thermostat; about 2-1/2 hours to run cable and install a blower-heater
Voltage tester, drill, 1/2-inch bit, drywall saw, fish tape, screwdriver, stripper, long-nose pliers, lineman's pliers
Cutting into walls; stripping, splicing, and connecting wires to terminals; installing boxes; running cable into boxes
Heater, box for thermostat, 12/2 cable, electrician's tape, wire nuts
A blower-heater unit fits between wall studs and is somewhat simpler to wire because it has a self-contained thermostat. Many units run on 240 volts. Check local codes for requirements.
A blower-heater must be a safe distance from nearby walls and furnishings. When choosing a location for the heater, maintain 12 inches from any adjacent walls. For safe and effective operation, locate the box 12 inches above the floor and keep the area 3 feet in front of the box clear. Check the manufacturer's recommendations before locating the unit.
Before cutting an opening for the unit, drill a finder hole and use a wire to check that the wall cavity is clear of pipes and wires. Use a drywall saw to cut the opening. Run the recommended cable to the opening.