The differences between a high efficiency and regular furnace

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.