Gas furnaces are also often known as domestic or home furnaces. They are used by people in their homes to maintain warm air. Unlike other furnaces that are used to melt metals or other substances, the domestic furnace produces a relatively smaller amount of heat, which is utilized to make the surroundings warm.
In the initial stages of the development of domestic heating furnaces, the fuel utilized was wood, oil, or coal. Later on, to cut the costs of operations, and also due to environmental issues, furnaces that used natural gas started being widely used by households. In US, the gas furnace is universally accepted by home owners, and most of these devices use LPG (liquefied petroleum gas) for operations. Some variants of this furnace have also evolved, which use methane or biogas.
Working of a Gas Furnace
Before we understand how does a gas furnace work, one needs to know the parts of this device. The furnace is principally divided into three sections. The first section is the made up of the burners, heat exchangers, draft inducer, and venting. The second section is made up of the controls and safety devices, and the third section is made up of the blower and air movement. All these parts work in cohesion to make the device work.
The furnace combines air and fuel (in this case gas), and the mixture is ignited. The resultant flame is then used to heat the air, which is circulated throughout the house. This process starts in the furnace burner, which is controlled by a thermostat. Sometimes, there are two burners if a huge volume of air is to be heated. When the temperature of the house drops down, the thermostat alerts the furnace.
A mixture of gas and air slowly starts entering the burner, and is ignited as a result of an electronic igniter. The air in the burner gets drastically heated, and starts rising through the heat exchanger, which is situated above the burner. It spreads inside the house and warms it up, while the exhausts are pumped out of the furnace from a vent, and is let outside the house.
In the meantime, fresh air is pulled into the furnace with the help of an electric fan. The air comes in through a large flat grill in the furnace, and passes into an enclosure known as the plenum. This enclosure is located opposite the heat exchanger, which heats the air coming in the plenum gets heated very quickly as a result of the high pressure. The heated air is then passed out of the furnace, into the house. This process is repeated till the temperature of the house reaches a specific level, after which the thermostat stops the heating process.
Nowadays, electric furnaces have slowly started replacing gas furnaces, though the latter are still preferred in US because of their low expensive.