Anatomy of a Furnace

Solid fuel boiler 3D rendered image in white

Furnaces keep you warm, and cleanse the air that you breathe. They’re a big part of your life, whether you know it or not. But, have you ever been itching to know, “How does my furnace work?” Well, lucky for you, here’s what happens when your furnace is on:


Similar to a car, the furnace must be ignited. For older furnaces, the ignitor is a pilot light. Newer models typically use electronic ignition.

The pilot light

(A concept you may already be familiar with) is a tiny gas flame that stays on all the time. It’s used to ignite a larger flame when the furnace gets switched on.

Electronic ignition

This uses a chain reaction that’s somewhat like a filament light bulb. This ignites the gas burner. When triggered by the thermostat, a current of electricity runs through the filament, creating enough heat to light the gas on fire.


The combustion chamber is where natural gas and air are combined. As you may know, oxygen is required to create fire. The furnace ventilates this chamber, feeding the fire enough oxygen to burn smoothly and efficiently. The ventilation also extracts the byproducts of the combustion.
As a furnace owner, be sure to keep your combustion chamber clean. You’ll have better quality air and higher efficiency if you’re diligent.


The warm air from your furnace is produced in the heat exchanger. The heat exchanger is located right above the combustion chamber. It collects the chamber’s heat waves. When the temperature inside the exchanger gets warm enough, the motor turns on, and distributes the hot air through the ducts of the house. This process repeats until the desired temperature is met.

Alkota Plumbing and Heating hopes we helped you learn a thing or two about your furnace. We want our valued customers in Anchorage, AK to be informed buyers. Call us today at 907-332-5325 to schedule a maintenance visit, repair, or installation.