By: Patricia Cermignano

A furnace is a major appliance that creates heat to maintain comfort throughout an occupied space and can run on either gas or oil. New high efficiency furnaces can save up to 50% in operating costs over a ten-year-old furnace.

A gas furnace has four main components: gas control valve, burners, heat exchanger and blower motor. 

  • Gas Control Valve- The furnace's fuel source, gas, is connected to the furnace through the gas control valve. When the thermostat initiates a call for heat, the gas valve opens, releasing gas which then flows to the burners.
  • Burners- The gas is ignited at the burners. The flames from the burners travel through the heat exchanger which then begins to warm.
  • Heat Exchanger- The heat exchanger is where the heat is created. When it warms and heat is generated, the blower motor is activated.
  • Blower Motor- The blower motor pushes the warm air from the heat exchanger through the ducts, circulating it throughout your home. As air is being pushed by the blower motor to a room, the blower motor creates negative pressure through the duct's return system and draws the air being circulated around the room. The warming cycle then repeats.

There are two types of gas furnaces- single stage and multi variable stage. Standard gas furnaces are commonly known as single stage furnaces. High demands for energy efficiency appliances have spurred advances in technology in gas furnaces. These new and improved gas furnaces are multi stage variable speed furnaces. Multi stage variable speed refers to the speed of the furnace's blower motor. The blower motor on a single stage furnace runs at only one speed: high. Whereas, the blower motor on a multi stage variable speed furnace can run at multiple speeds.

How does a gas furnace work? On milder winter days, it is not necessary for the furnace to run at maximum speed. Unlike single stage furnaces, multi stage furnaces have the ability to run at a lower speed, thus reducing energy consumption and increasing indoor comfort. On colder winter days, the furnace will run at the high stage only until your space has reached the desired temperature. Once your space has reached the thermostat's set temperature, the furnace will slowly decrease to the low stage. This will result in your space maintaining comfort, having increased air quality with constant air circulation and reducing energy consumption.

The benefits of gas furnaces include, but are not limited to:

  • Energy Efficiency- The blower motor, which mostly runs at the lowest speed, uses less electricity. This significantly reduces electric bills.
  • Improved Comfort- The blower motor runs at a lower speed for a long time, improving air flow. This keeps the temperature of your space more consistent, and keeps you more comfortable.
  • Increased Air Quality- The blower motor is constantly circulating air through your space and through your furnace's air filter at a higher rate than a single stage furnace. This removes more pollutants and improves air quality.
  • Noise Reduction- The blower motor's speed starts slowly, then gradually increases, which creates less noise.

Bob Cermignano Air Conditioning & Heating, Inc. is in the business of keeping you warm and comfortable in the cold winter months. For additional information on gas furnaces or to ask any questions, please call our office at 610-642-6323 or visit our website.