Lennox HVAC Wiring

Safety Precautions

• When you work on any electrical system, it's critical to make sure the power is turned off at the circuit breaker box. Circuit breakers control the flow of electricity from the utility provider to the various circuits in the home. By turning the switch marked "master" to the off position, you will ensure that you will not come in contact with "hot" electrical wiring. You should also switch off the individual circuit breakers for the unit you are working on, and shut off any switches at the unit itself. This will give you added protection in case someone comes along and flips the main switch back on. It's also best to leave a note at the breaker box to help prevent such an event.

Lennox HVAC Wiring Type

• Lennox HVAC units are approved only for use with copper wiring. To make sure the wiring you plan to use is copper, strip one end of it to look color of the wire. Copper wire is the color of a new penny. Wires that are gray or silver colored are probably aluminum or some other metal.

Power Requirements

• Because Lennox makes a wide range of types and sizes of HVAC units, the power requirements vary from model to model. Consult the wiring diagram for the required amperage and voltage ratings for your particular unit. Look at the label on the main breaker panel to make sure your circuit breaker can handle the load. For example, a Lennox unit that requires a 110-volt hookup is not compatible with a 220-volt breaker.

Lennox Wiring Color Codes

• Lennox wiring diagrams often use color codes. "Y" stands for yellow wiring, while "W" is for white wires. "G" stands for green wiring and "R" stands for red. Often in Lennox wiring diagrams you will see color codes with a number next to them, such as "W2." This refers to a second white wire within the system. Sometimes you will find two or more wires of the same color. When wires are duplicated, they will always connect different components. The first white wire may connect the compressor to the wall control, while the second white wire might connect the transformer to the junction box. Refer to the wiring diagram for your HVAC unit for the specific wiring paths.

Thermostat Control Wiring

• Thermostat controls connect to both the transformer and the HVAC component. Refer to your specific unit's wiring diagram for the proper wiring path. All Lennox control systems use 24-volt circuits between the home control and the heater or air conditioner. The voltage is regulated though a transformer inside the HVAC unit. Use a voltmeter to check that only 24 volts of electricity is being provided to the control system.