Understanding Electrical Wiring Diagrams for HVAC

Electrical wiring diagrams are known as schematics.


Thermostat installation requires a knowledge of electrical wiring diagrams.
Schematics show what components are used in an electrical circuit and how they are connected. There are two types of objects shown on shematics: components and nets. Nets are wires that connect items. Component objects show a component name and type. .
Old homes are especially prone to electrical issues.

An understanding of electrical wiring diagrams is essential for HVAC system updates in older homes. Older homes especially are prone to electrical wiring problems. When these homes were originally built many appliances did not exist, like dishwashers, dryers and air-conditioners. The electrical wiring in older homes is hardly ever adequate to sustain the many modern appliances people use today.


Heating, vacuuming and air-conditioning systems (HVAC) are large systems that require plenty of energy to operate. In addition to understanding the load your electrical wiring can handle, schematics help you establish where to put thermostats, and which style of wiring you should use for your HVAC system.


There are two types of schematics. Some come in data sheets and technical documents. These schematics show only the circuit (or partial circuit) and perhaps a few notes. The other type is the actual drawing used to create a circuit board. These schematics represent a full system and include more information, like the author's name.

About the Author

Melissa Bajorek began writing professionally in 2001. Her work has appeared online, in daily newspapers and on websites owned by Gatehouse Media, in monthly periodicals and for local and regional radio. She writes about a variety of topics, from new technology to animal husbandry. Bajorek has an Associate of Arts in business management from the University of Phoenix and holds certifications in marketing and advertising.