How Does a Warm-Air Furnace Work?

If you’ve got a furnace keeping your home warm, then you’re like most homeowners in the area. A furnace is a reliable, cost-effective whole-home heating system that most homes are already set up for. It typically (though, not always) runs on natural gas, a clean-burning fuel, and today’s units are very efficient.

So how does it work?

Here are some of the basics of a furnace’s operation.

  • The temperature in your home drops and the thermostat alerts the furnace.
  • The gas valve opens up and ignites when an ignitor, typically made of a material like silicon carbide that gets extremely hot when an electric current goes through, lights the burner.
  • The heat from the flame moves through the heat exchanger, heating it up as toxic byproducts (like carbon monoxide) escape to the other side and vent away through the flue.
  • Once the furnace heats up, air from around your home enters the unit, after it gets sucked through a filter.
  • The air blows back out through the ducts in your home.
  • The gas valve closes once temperatures are at an acceptable level, and the fan shuts off soon afterwards.

Other components

Of course, the parts we mentioned are not the only things within your furnace helping to keep you warm. It’s a complex piece of equipment with various controls and parts that keep things running smoothly and safely, including:

  • Limit switch
  • Fan switch
  • Air pressure switch
  • Flame rollout switch
  • Flame sensor
  • Spark ignitor
  • Draft inducer
  • Draft inducer motor
  • Blower motor
  • And much more!

Because of the intricacy of the inner workings of this system, and the fact that gas leaks and carbon monoxide leaks are always a possibility, you should only allow a professional to service your heater. And be sure to schedule maintenance so that you can avoid issues in the first place!

Call the Aurora, CO heating specialists at APC Plumbing & Heating. We have someone in your neighborhood today.


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