Everything You Need To Know About Furnace Wiring Diagrams

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Goodman Gas Furnace Wiring Diagram Goodman Furnace Wiring Diagram

A wiring diagram for a furnace is an essential tool for anyone installing or replacing a furnace. Having a wiring diagram handy allows an experienced technician or novice do-it-yourselfer to quickly locate the appropriate wires, identify the circuit breakers, and ensure the electrical connections are properly made. In this article, we’ll explain the basics of a furnace wiring diagram and cover some of the most common wiring diagrams.

Types of Furnace Wiring Diagrams

Furnace wiring diagrams come in two basic varieties: residential and commercial. Residential wiring diagrams are used for furnaces installed in homes, while commercial wiring diagrams are used for furnaces installed in businesses and industrial settings. Both types of wiring diagrams are similar in terms of the layout of the circuits, but the commercial diagrams have more detailed information about the components and their connections.

Components of a Furnace Wiring Diagram

Furnace wiring diagrams typically include the following components: a power source, furnace control board, furnace limit switch, blower motor, and thermostat. The power source is typically a circuit breaker or fuse box, while the furnace control board is the central hub of the furnace’s electrical system. The limit switch is used to turn the furnace on and off and regulate the temperature, while the blower motor is responsible for circulating air throughout the home. Finally, the thermostat is used to regulate the temperature of the home and to turn the furnace on and off.

Reading a Furnace Wiring Diagram

Reading a furnace wiring diagram can be daunting for the novice do-it-yourselfer. Fortunately, there are several helpful resources available that provide detailed instructions and diagrams. Many of these resources are available for free online, and some are even available in print form. Additionally, many heating and air conditioning companies offer in-depth training courses on furnace wiring.


Understanding how to read a furnace wiring diagram is an important skill for anyone who is installing or replacing a furnace. With the right information and resources, anyone can safely and confidently complete the job. Knowing the components of a furnace wiring diagram, as well as how to read them, will help ensure the job is done correctly and safely.