How a furnace works

A furnace is an appliance that is permanently installed in your home to provide heat to an interior space through fluid movement (air or hot water). The most common fuel source for modern furnaces is natural gas or electricity.

Standard Gas Furnaces rely on natural gas or propane to provide energy used for generating heat. While the temperature in the home falls below the level set on the thermostat, an electric pilot light automatically ignites to heat a burner. The burner utilizes some form of gas to generate heat within a combustion chamber inside the furnace. The heat passes into a heat exchanger, which typically consists of a series of copper tubes/pipes. When a fan blows air onto the heat exchanger the air is heated. This heated air is then blown through a series of ducts to heat the home. Exhaust fumes from the combustion process exit the furnace through a gas flue or chimney.

High-Efficiency Furnaces feature a second combustion chamber, which captured exhaust gases and moisture before it exits into the chimney. This second chamber condenses the gaseous by-products to form a liquid and then extracts any remaining heat. This heat is then transferred into a second heat exchanger which supplements the primary heat exchanger and helps to heat the air. The small amount of remaining waste is exhausted from the home through a small chimney or even a simple pipe in the wall.

Furnace Filters were initially designed to protect the furnace and the fans of the indoor heating system. It is a detachable filter made of standard fiberglass and is placed between the air inlet and the furnace fan, motor and heating panel. Its main use is to protect these internal parts from dust particles which can reduce the efficiency of the furnace. Airborne particles accumulate on the furnace motor or fans, therefore increasing the workload and decreasing the efficiency. Furnace filters are being used to improve the quality of indoor air. Filters available today are redesigned to protect internal parts of the furnace along with enhancing the quality of the air. The standard fiberglass filters are now replaced with highly efficient filters capable of filtering very fine particles from the air. People suffering from asthma and other allergies can make use of high-efficiency filters to create a pollutant-free environment and reduce the incidence of their medical condition.