Learn All the Parts of Your Furnace

Learn All the Parts of Your FurnaceLong Island winters are often brutal, and even one night without heat can be a real problem. Knowing a little about how your furnace works can help you troubleshoot problems and communicate more effectively with HVAC technicians in the event you need service.

Although a furnace has few moving parts, it’s a complex piece of machinery with a number of important components.


When the temperature in your home dips below the thermostat setting, the thermostat sends a signal to the furnace. A valve opens, and gas enters the burners. The pilot light ignites the gas.


The blower turns on and draws in air from the cold air return, the duct that sits upwind from the filter. The air moves through the filter and into the unit. As it passes over the heat exchanger, it’s warmed.

Heat Exchanger

The heat exchanger is the fluid-filled metal chamber that heats up the air coming into the system.


The large metal box on top of the unit is the plenum, which holds warm air before it’s sent through the ducts and into your home.


The flue exhausts the combustion gases the furnace produces through the roof or walls.

Why Maintenance is Critical

Without regular maintenance, a furnace will lose about five percent of its efficiency each year. This raises your energy bill and causes more wear on the system as lubricants dry up and dust builds up on essential components. In turn, this leads to increasing problems as one defective component affects the performance of all the others.

Annual maintenance is inexpensive and includes tasks like:

  • Tightening gas and electrical connections.
  • Measuring airflow.
  • Lubricating moving parts.
  • Testing the controls for proper cycling.
  • Checking for carbon monoxide leaks.
  • Testing the thermostat for accuracy.

In addition to a yearly checkup, checking the air filter each month and replacing it when it’s dirty will extend the life of your system and help prevent operating problems.

For more information on how your heating system works, or to schedule a preventive maintenance visit, please contact us at Cool Power, proudly serving the Long Island area.

Our goal is to help educate our customers in Hauppauge, New York and the Long Island area about energy and home comfort issues (specific to HVAC systems). For more information about furnace components and other HVAC topics, download our free Home Comfort Guide or call us at 631-292-0629.

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