I'm trying to install(replace) a wall fan forced electric heater. There are three wires coming out my wall: black, white and bare copper. However, there are four wires coming out of the heater: two black and one blue connected to the motor and one green connected to the wall box. Out of the four wires coming from the heater, one black and the blue are tied together with a "L1" sign. The heater itself doesn't contain a thermostat. A separate thermostat was previously installed. Voltage used is 240V/208V. Can you help explain how I can connect the wires? Thanks!

wires from the wall

new heater with wall box


Well the fan is going to need 240 volts. If the existing wiring has not been wired for a 240 volt fan then it needs to be changed. This would involve opening the main breaker panel. I would recommend an experienced electrician for this. If it is already set up for 240 then that part is good.

The owner's manual for the fan should explain the wiring but my guess would be since the fan is rated for 240 or 208 then one of the wires labeled L1 (possibly the blue) would not be used for 240. The other black wire should be labeled L2. The two blacks would then be connected to the black and white of the cable, and the green is your ground wire that gets connected to the bare wire of the NM cable.

If this is your first project with electrical work I would recommend getting the assistance of an experienced electrician to guide you.

Good luck! 😊

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