HOW DO GAS FURNACES OPERATE?
In simple words, a central gas heating system operates by increasing the temperature of cold air through a cyclic process. Here’s a simplified explanation:
- Propane or natural gas combustion in the furnace’s burner generates heat.
- The generated heat passes through a heat exchanger, heating it.
- Air from the home’s ductwork is propelled over the heat exchanger, warming the air.
- The furnace’s blower then pushes the heated air into the supply ductwork, dispersing it throughout the home.
Components of a Central Gas Furnace
Various components within the central heating system collaborate to ensure your comfort.
- Temperature Control: Regulated by the furnace control board, this component initiates the heating process upon receiving a signal from the thermostat or control system.
- Draft-Induced Fan: Draws air into the burner assembly, thereby facilitating the combustion process. It also helps in warming the heat exchanger before the exhaust is directed outside the home.
- Gas Burners: When heat is required, the gas burner valves open, allowing gas to flow and ignite, initiating the combustion process.
- Ignition Switch: Gas flows over the igniter to create a flame, which is then directed through the burners to heat the heat exchanger.
- Heat Exchanger: This component adds heat to the indoor air. Gas combustion occurs within the heat exchanger, generating heat that warms the passing air. An efficient heat exchanger design enhances the energy efficiency of the gas furnace.
- Blower Fan: Utilizes the return venting to blow air over the heated heat exchanger. The conditioned air is subsequently distributed throughout the home via ductwork. Some furnace models feature a multi-speed blower fan for improved efficiency.
- Flue: Acts as an exhaust for gaseous by-products of combustion, ensuring safe expulsion outside the home.
Gas Furnace Types
Gas furnaces are available in various configurations to suit different spaces. They can also be classified into the following categories:
- Non-condensing Furnaces: These furnaces vent exhaust gases outside the home, usually through the roof.
- Condensing Furnaces: Utilizing a second heat exchanger, these furnaces heat the air by condensing exhaust gases, leading to higher efficiency.
- Modulating Gas Furnaces: These furnaces continuously adjust the amount of fuel burned to maintain the desired thermostat temperature. This modulating feature helps minimize indoor temperature fluctuations.