Winter is almost upon us and now is a great time to get a basic understanding of how your gas furnace works. Even if you don’t plan on doing repairs or maintenance yourself, grasping these basics will improve communications with your HVAC technician and allow for quicker repairs.

The components of your furnace are the control system (thermostat and electrical controls), gas valve, burners, heat exchanger, blower, and duct and ventilation system. The combustion gas is expelled from your home via a flue pipe.

Your furnace will switch on when it receives a signal from your home’s thermostat. When it sends its electronic message to the furnace, gas valve opens and ignites the burner below the combustion chamber. This valve works in conjunction with the thermostat to regulate the amount of gas that enters your furnace.

The flames from the burner heat a metal component called a heat exchanger. The generated heat circulates through looped tubes of a heat exchanger, transferring the heat to the air. It’s important to note that a damaged heat exchanger not only has a direct effect on furnace efficiency; it also is a health hazard. (read our article about the dangers of a cracked heat exchanger here).

As heat circulates through the heat exchanger, a blower motor and fan move it through a plenum. From there, it flows through the ductwork in your home. The ductwork leads to vents that allow heat to enter individual rooms.

While all of this is going on, exhaust from the combustion process exits your home via a flue pipe.

Maintaining your gas furnace

Proper maintenance is critical for the efficient function of your furnace. And now is a great time to schedule an inspection and tune-up with a qualified HVAC technician before temperatures drop further.

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