Furnace filters are designed to stop dust particles from entering the heating and cooling system. They reduce the stress on the fan motor and create a more energy efficient system.

Furnace filters also decrease the amount of dust and bacteria circulating within the home.

Changing the furnace filter every 30 days to 90 days can assure optimum performance and improved air quality throughout the year.

Step 1: Turn the furnace or air conditioner off before changing the furnace filter. If an on/off switch cannot be located near the furnace, turn the system off by switching the thermostat to the off position.

Step 2: Find the furnace filter and remove it. On most heating and cooling systems, the filter is located somewhere between the cold air return duct and the furnace blower. Hopefully, there is an access panel on the front or side of the furnace to facilitate filter changes.

Step 3: Make note of the size of the filter. If the size is not printed on the filter, measure the height, width and thickness of the filter and round each up to a whole number.

Step 4: Select the filter that is right for you.

Inexpensive fiberglass filters will need to be changed every 30 days and have a MERV (Minimum Efficiency Reporting Value) less than 5. This means they will only catch large particles of dirt and dust.

Pleated filters capture 99 percent more dust and dirt particles than their fiberglass counterparts. A MERV 8 filter will trap dust mites, mold spores, hair spray and pudding mix. Filters with a 13-16 MERV rating will capture all bacteria, tobacco smoke and most other household particulates.

Electrostatic filters, such as those made by 3M Company, change the static charge of the air as it passes through the filter. This decreases the amount of particles accumulating in the air and can effectively reduce symptoms in allergy suffers.

Step 5: Install the new filter into the furnace with the thicker, reinforced side of the filter material closest to the furnace blower. If there are air flow arrows printed on the filter housing, these arrows should be pointing toward the furnace, indicating the direction of the air as it flows through the filter medium and into the heating and cooling system.

Step 6: Once the filter is securely in place, replace the access panel and make note of the next filter change date on your calendar.