Gas Furnace Functions

The process performed by a regular conventional gas furnace is quite simple in theory. The gas furnace is located in a large box and in order to control the temperature in your home or office the furnace takes in cold air, cleans this cold air by running it through an air filter, heats up the cold air by the use of a gas burner and a steel heat exchanger, then distributes the warm air through the ductwork in your home or office by using a blower. So as you can see the theory behind the heating and cooling cycle performed by a gas furnace is quite simple.

Gas Furnace Process

Once the gas furnace has completed the heating process and the warm air is inside your home, the air will begin to go through a natural cooling process. This cooling process makes it necessary to remove the cool air from you home and replace it warm air. This continual air heating and cooling exchange is performed by using return ducts which suck the cool air back to the gas furnace through return air grills and ductwork so it can run through the heating process again. Located on the return air grills and ductwork there is a device called a humidifier. This helps to control the humidity of the air inside your home so that the heated air is not too dry. This is an important process as the air can become very dry as is continues to go through the heating and cooling process performed by the gas furnace.

Gas Furnace Main Types

A conventional gas furnace is defined as anywhere up to 89% AFUE (annual fuel utilization efficiency) whereas anything above 90% is defined as a high efficiency condensing furnace. These high efficiency condensing furnaces are a little more complex than a conventional furnace. It uses slightly different technology to perform the heating and cooling function. The main differences lie in the method used to extract heat from the combustion process and the method used to exhaust the combustion gases. To put it simply, there is not a greater overall efficiency difference in the combustion process in a high efficiency condensing furnace compared to a conventional gas furnace. The difference in efficiency lies in the heat extraction process after combustion has occurred. Both the conventional gas furnace and the high efficiency condensing furnace use gas burners with electronic ignition systems.

The gas furnace heating system can sound a little complicated at first but it’s actually quite a simple theory. The engineering and design of a HVAC heating system is much more complicated to understand and implement. However, if you put in the effort to understand how a gas furnace works then performing simple maintenance and troubleshooting can be done yourself without hiring the services of a HVAC contractor.

This article has outlined a simplified version of the heating process performed by a gas furnace, and also what happens to the air once the cooling process begins. There are a number of other articles and videos on this Vancouver heating and cooling HVAC website that may also help further your knowledge on other HVAC aspects in addition to the function and process performed by a gas furnace.