If you're one of those people who only change their furnace filter once a year, you may well be shortening the life of your furnace, as well as breathing in some really dirty air.
Check the documentation that came with your furnace.
Recommendations vary based on a number of factors: the type of filter you use, how many pets you have, whether anyone in your home has allergies, etc. If you don't have your owner's manual, check your furnace filter monthly (especially throughout the winter heating season) and replace or clean it as needed, depending on the type of filter you use and how dirty it looks. To determine if it needs replacing or cleaning, remove the filter and hold it up to the light. If you can no longer clearly see light, change the filter! Many costly repairs can be avoided with regular filter changing. If you don't change the filter, lack of airflow through the furnace can cause it to overheat and shut down.
Filters are relatively inexpensive and easy to change, so there is little reason to wait. If you don't change or clean your filter often enough, the filter can get clogged with dust and other airborne particles, forcing your furnace to work harder to maintain airflow. This will reduce your furnace's efficiency and can cause damage. Filters are designed to protect the blower motor from dirt. Filters come in a variety of sizes and styles, from very basic models to those that are able to remove allergens and dust from the air. If you have a smoker in your home or pets who shed their coats, it's a good idea to clean or replace your filters more frequently. Be sure you know which size filter your furnace needs and how to reinstall it correctly, since putting it in backward will decrease the filter's efficiency.
In general, the frequency with which you replace or clean your air filter depends on the type of filter you are using:
Disposable Filters: Simple, disposable air filters should be replaced every 4 to 8 weeks.
Washable Filters: Washable filters should be removed and washed every 4 to 8 weeks. If you keep your furnace fan running continuously, it is better to clean the filter every 3 to 4 weeks.
Metal Filters: The filter media used in these metal frames is very thick and dense. Every 8 to 10 weeks, you should replace the filter media in the metal frame.
Electrostatic Filters: Reusable electrostatic air filters should be thoroughly washed every month. As the electrostatic filters get older, they should be cleaned more often.
Electronic Filters: If you are using an electronic filter in your furnace, it should be cleaned every month. These should be cleaned very carefully. If any internal wires are broken during cleaning, the filter will cease to work.
These are very general guidelines to follow when deciding how often to replace your furnace filters. In addition to considering the type of filter you are using, you also should factor in the quality of the air being filtered in your home.
For more information, contact Elisa at the CSU Moffat County Extension Office, 539 Barclay, 824-9180.