A gas furnace is a forced home air heating system that reacts when the indoor air temperature drops below the programmed setting on a thermostat. The heart of your home furnace is the burner controlled by a thermostat. When the temperature indoors falls below a certain point, the thermostat alerts the furnace which combines air and fuel and the mixture gets ignited by an electronic igniter. The combusted, hot gas begins to rise through the heat exchanger situated above the burner and heats the air which is circulated throughout the house. The remaining exhaust exits the gas furnace from a vent, which is let outside the house. The whole heating process starts at the heart of the system, which is the furnace controlled by the thermostat. Some furnaces come with two or more burners where huge volumes of air are heated for distribution. Meanwhile, an electric fan situated inside the furnace pulls in fresh air which comes through a flat, large grill located in the floor, wall or ceiling of the house. Before the fresh air reaches the furnace, it must filtered properly of dust and other particulate matter. If the cold air is not properly cleaned then it can have an adverse effect on its operation. You need to replace furnace filters every month and also keep the duct vents clean to provide maximum working efficiency and heat to your home. The filtered air passes into an enclosed space known as the plenum which is located opposite to the heat exchanger. The exchanger then heats the air very quickly which comes from the plenum as a result of high pressure. The hot air is passed out of the furnace and through the duct work into your home’s indoor spaces. The ignited gases that are used to create the heat are vented through a shaft in the wall or roof. However in some furnace installations, a humidifier is added near the place where the intake duct is located so that the drying out of heated air can be mitigated. Humidifiers are directly connected to the water line by a tiny copper pipe. Another pipe is also used to drain away the condensation created from the process. Till the temperature inside reaches a specific point, the process is repeated until the set temperature is reached.