Understand Your Furnace- Learn All Its Important Parts!

Web StaffHome Tips, HVAC

These days, Houston, all we can think about is getting back to our warm homes and beds, put on our pj’s and kick back with a glass of whatever it is that makes us feel warm inside, all to forget the freezing cold and rain that has taken over our city. Sure, we recall wanting a “real winter” sometime in the last couple of months, too, but we probably aren’t the only ones who are going to be careful with what we wish for next time around, are we?

Thus, we now realize that having a warm and cozy home during the winter is a true blessing – thanks to your heater. Without it, you’d be living in an icicle and resort to sleeping next to the fireplace with every article of clothing you own on your body. But with a working furnace, staying warm and comfortable in your home doesn’t have to become a distant dream. Even more than that, a homeowner who knows the parts of his or her heater and how each works is a responsible one, and always reaps the benefits. It’s about knowledge, and that’s what every good homeowner should have when it comes to the complex (and expensive!) systems in the home.

With the help of Lewis Yancey, an HVAC coach at John Moore Services, we want to shed some light on identifying the most important parts, what their purposes are, and why it’s so important to take good care of them. Read on!

Parts of a Furnace


The gas burners are ignited by a pilot flame or electronic ignition that is incorporated in most modern gas heaters. The main function of the gas burners is to heat up cold air using heat exchangers that are made of stainless steel. After, the warm air is distributed through the ducts by a blower motor.


Run by the blower motor, this is one of the crucial parts of the entire system, and it helps set up the air draft that is required for the operation of the heater itself. The blower’s main purpose is to allow for easier intake of cold air and then channel it through to the heat exchanger chamber.

Heat Exchanger

The heat exchanger is made of heavy gauge metal mixed with alloys that resist temperatures above 2000° F to accommodate the extremely high temperatures that are reached inside the combustion chamber. That’s why it is so important to perform annual inspections and examine the state of the heat exchanger on a regular basis. If not, there could be dangerous consequences.

“The heat exchanger, which is talked about the most, is the part that takes the carbon monoxide out of the house and is usually visible, so it needs to be regularly inspected for cracks or rusting over time- anything that can allow even the possibility of carbon monoxide leaking into your home.”


Capacitors store electricity and help compressors and blower motors actually start and operate. Specifically, start capacitors provide motors with a boost in starting torque. Faulty capacitors lead to overheating, intermittent motor operation, humming noises or even outright blower motor failure.


Yancey says that the vents are usually one of the only parts that are directly visible to the homeowner. Vents are usually made of stainless steel or PVC, with PVC being used most often due to its durability. The vent pipe works by carrying the exhaust gasses that are formed due to combustion out of the home, which is a very good thing.


This is one of the key components designed for safety. The flame sensors, pilot, electronic or hot surface igniters monitor the presence of the flame in the combustion chamber. If the flame in the combustion chamber goes out, then these sensors stop the flow of gas into the chamber using their link up with the gas control valve.

Control Board

“The control board is the brain of the entire operation; it controls the ac and the heat,” Yancey said. “It’s the communicating part.”

Modern ones use integrated circuit boards to monitor the its operations. It works because of light emitting diodes that show failure codes if the gas furnace is malfunctioning in any way.

Keep Your Ears Open

Most of the parts of it are usually behind a door. According to Yancey, a person can actually hear certain parts of it working.

“The furnace is made up of the blower motor, the heat exchanger, the blowers, and the control board, among a few others,” Yancey said. “Those are the main components of it, and none of those can be seen to the naked eye. Usually the only thing you see is the venting coming out of it through the roof, so being able to hear the things you can’t see helps when examining the state of your unit.”

Listening for the parts really helps. If you listen, you should hear a small motor come on, hear the lighting of the burners, and you should hear the fan come on in the heating stage.

“Unless you know what you are looking for, it’s hard to see the parts right then and there,” Yancey said. “It just helps in terms of identifying any potential issues. If things don’t sound right or you don’t hear an expected sound, chances are it’s a problem.”

Be Smart: Consult a Pro

We recommend always calling an experienced John Moore HVAC technician to come to your home and check everything out for you. We aren’t just saying that, either. There are fragile and expensive parts that need to be removed or moved, and only professionals have the hands-on experience to get things done correctly and safely.

For example, the blower motor should be checked regularly for dust and debris trapped deep inside, the capacitor should be checked to make sure it is within range of its proper functions, and the control board should be checked for any pitting, darkening, rusting, or burning. These, among other things, should be looked at annually.

“Homeowners need to be very careful when it comes to checking these things and furnace repair,” Yancey said. “That’s why I suggest bringing in a professional- it’s just so much safer. You have high voltage and low voltage in that same area, and there is a possibility for major damage to not only the equipment but to the person as well.”