If you live in a northern climate, you probably don't have central air or a system that combines both heating and cooling in the same unit. It is common in northern climates to run a furnace for heating in the winter and window air conditioning units and fans for cooling the home in the summer. You might be surprised to learn that your furnace can be used to cool your home even if you don't have an air conditioner.
How the Furnace Works
The burner on your furnace heats the air with a flame. The hot air is then forced through the ducts via a fan that comes on once the air is heated. This forces warmed air to all areas of your home. A cold air return sucks in fresh air to continue the process as your furnace kicks on and off as dictated by the thermostat. Once the burner turns off, the fan continues to blow until the unit cools and all the warm air is extinguished. The fan typically has three settings, on, off and automatic. You probably run your fan on automatic so that it comes on when the air is warm and shuts off when the air is cool. But, you can take advantage of the blower to circulate air even when you aren't running the furnace.
Circulating Cool Air
In the summer time, you can set the fan to the on position to circulate cool air in the home. The furnace unit draws air into the unit and circulates it through the duct work to all areas of the home. The air is not chilled by air conditioning, but it creates a breeze that works by the windchill principle to cool you off. This works best if the cold air return of your furnace is located in a cool basement or other cool area. Pulling the air back to the basement where the cement slab remains cool actually cools the air off as the cement absorbs some of the heat.
For furnaces located in rooms with a window, you can take advantage of the window to create more airflow. When the fan is turned on it will draw fresh air from the outside and circulate it through the home. Turning the fan on in the evening after a hot day and opening the window to let in cool air will cool the home off quickly. Circulating air with the blower fan on your furnace also evens out the air temperature throughout your home cooling rooms on upper levels.
Effects on the Motor
Some worry that running the fan continuously puts too much work on the motor and will wear out the blower fan. Because the most wear and tear is experienced with stopping and starting of the fan, Bronson Shavitz from Shavitz Heating and Air Conditioning claims the running the fan continuously may actually extend the life of the fan motor.
Running the blower on your furnace takes electricity and will increase your electric bill. How expensive the fan is to run depends on the age and efficiency of the blower on your furnace. Running the blower on your furnace to circulate the air in your home may reduce the need for air conditioning or reliance on window and room fans. The costs associated with running the furnace fan may be less than the cost of running supplemental fans for a few hours or air conditioning.
When hot weather strikes and your home begins to heat up to uncomfortable levels, try switching on the blower fan to your furnace to circulate air and make your home feel more comfortable. The blower on your furnace can also be used in conjunction with a window air conditioning unit to assist in circulating the cooled air throughout the house. If you would like to purchase a window air conditioning unit, check out a company like Aggressive Mechanical Contractors.