The Heart of Warmth: Unveiling the Essential Components of a Furnace HVAC System

June 12, 2023
The Heart of Warmth: Unveiling the Essential Components of a Furnace HVAC System

There’s a funny smell, a rattling noise in the night, or maybe your house just isn’t warming up.

And... You know nothing about the parts of a furnace.

While understanding the anatomy of your gas furnace won’t guarantee you can fix the issue at hand, it’s a start. So, let’s dive into what you need to know about the parts of a furnace.

Components of a Furnace

Return Register

The return register is the part of a furnace from which air returns to your furnace after being heated. It’s right below where hot air leaves, and it’s usually next to an outside vent or hole in the wall that brings cold air into your home.

Return Duct

The return duct is the part that brings air back into your furnace from its final destination. In a house, this would be any vents or rooms where hot air is being pushed out of the home – usually through an HVAC vent cover on each floor.

Air Filter

An air filter is a part that catches dust and other particles in the air before they get blown into your home. It’s important to regularly change the air filter as it gets dirty over time—especially if you have pets or live near a busy street.


The blower is the part that blows air through your components and into your home. They can work with either electricity or be powered by a belt, so if you hear a loud noise coming from this area – it might need to be replaced.

Blower Motor

The blower motor is the part that powers your furnace’s components. The belt turns this, which then heats the air and blows it into your home. If there are loud noises when you turn up or down the heat, this might need to be replaced too.

Blower Chamber

The blower chamber is the part that houses your components. It’s usually located within a metal casing to keep it protected, which can get hot when components are running, so be careful!


The burners are the components of your furnace that actually heat up air and make it usable. It usually consists of a gas valve, igniter, flame sensor (to keep you safe), and vent ports to let out carbon monoxide, which is poisonous if not released properly.

Flame Sensor

The flame sensor is the component that stops components from working if it doesn’t detect a gas burner lit. It’s important to make sure this area works properly, as your furnace can shut down or malfunction without one in place!

Pilot Light or Electronic Ignition

The pilot light is the little flame that lights up components and keeps them working. Without this, your furnace would be useless – so make sure to take care of it!

Burner Cover

The burner cover is the component that surrounds your burners.

Combustion Chamber

The combustion chamber is the component that surrounds your burners. It’s usually made up of a heat exchanger, tube sheet, and blower housing, all to keep components working properly!

Heat Exchanger

The heat exchanger is the component that heats the air. It’s usually located next to your burners, and it needs to be cleaned regularly for optimal performance – especially if you have pets!

Supply Plenum

The supply plenum is the component that sits above your furnace and delivers air to components. It’s usually covered in insulation, as it can get super hot; you definitely don’t want anything touching this area!


The damper is the component that controls how much air gets into your home. It’s usually located in a metal casing atop components, and it can have manual or automatic components, depending on your specific furnace model!

Supply Duct

The supply duct is the component that delivers air from your plenum to components.

Supply Register

The supply register is the component that delivers air from your plenum to components.

That’s a lot to remember, but luckily, you don’t have to. We can help you with our heating services, give us a call at (210) 446-0105 or click the link below.

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