How to Wire a Reznor Heater

Turn off the circuit breaker that controls the Reznor heater's electric supply. The heater should have its own circuit breaker and the wire should equal or exceed 14-gauge in thickness. The identification tag on the unit identifies the wire's minimum requirements.

Remove about 3 inches of the plastic sheathing that covers the high-voltage wire that leads to the unit. The two-strand wire with ground will have two insulated wires, with black and white colored insulation, and an uninsulated copper ground wire. The three wire strands will have a protective plastic sheathing covering them.

Strip 1/2 inch of insulation from each wire. Separate the wire ends and place the wire in a safe place where the ends do not touch anything.

Turn on the circuit breaker to the heater.

Place one lead of a voltmeter on the copper ground wire. Touch the black wire with the other voltmeter lead. If the voltmeter reads 115 volts, consider the black wire to be hot. If the voltmeter reads zero, then test the white wire to verify the white wire contains 115 volts.

Turn the heater's circuit breaker to the off position. Label the hot wire with masking tape.

Open the heater's electrical panel, located on the left-hand side, with a 1/4-inch nut driver. Place the screws in a safe place.

Push the high-voltage wire into the "Line-voltage entrance" hole, as marked. The hole, located on the back of the heater near the top of the unit, has a black rubber grommet that the wire slides through.

Feed the high-voltage wire to the high-voltage control box, which mounts inside of the electrical panel.

Twist the hot wire (with the masking tape) to the wire with an "L1" tag and secure them with a wire nut.

Twist the second insulated wire to the wire with a "Neutral" tag and secure them with a wire nut.

Connect the copper ground wire to the green ground screw with a flathead screwdriver. The ground screw connects to the unit's electrical connection box.

Replace the electrical cover and secure it with the saved screws.

Loosen the thermostat screws, found on the back of the unit near the bottom.

Extend the thermostat's wire to the heater.

Twist the thermostat's red wire around the "R" terminal and the white wire around the "W" terminal. If the thermostat has three wires, twist the third wire, usually green, around the "G" terminal. Tighten all of the thermostat terminal screws.