When and how often to change your furnace filter | Dayton Ohio weather

Knowing when to change the filter to your heating and air system in your home is important. We have many customers ask us when should they change the air filter, and our answer is, “it depends.”

Several factors determine when your filters need to be changed, but the main rule of thumb is if it looks dirty, change it! You shouldn’t wait until the filter is completely filthy though, because that means your heating and cooling system is not running at its full potential.


If you’re thinking that you only have to change your filter once a year, you may be shortening the life of your furnace. You should check your filter monthly and change if it is dirty. To determine if it’s too dirty, 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 could cause it to overheat and shut down. Similarly, a dirty filter can cause an air conditioner to shut down because the coils freeze up when airflow is inadequate. Both events stress the system.

Do you or anyone else in the home have allergies? Another main factor in how often you should change the filter is the occupants in the home.

If you have anyone who suffers from allergies, you should be changing the filters more often than recommended. This will help remove more of the allergens from the air in your home. If the filter is full and dirty, it won’t be able to trap them.


Filters are designed to protect the blower motor from dirt and remove particals from the aire. When buying filters for this task, buy a filter based on your needs. There are inexpensive glass fiber filters that will do the job, but if you want to reduce airborne dust in your home, you could start with the best of the inexpensive 1-in. disposable filters. A standard pleated filter costs a bit more than a fiber glass filter or better yet, to remove even more small particles, install an inexpensive, electrostatically charged fiber filter. Make sure to check the filter monthly and change it when it’s dirty (not just every three months as recommended).

Finally, whatever filter you use, make sure you reinstall it correctly, with the arrow on the filter edge pointing toward the blower motor. Putting it in backward decreases the filter’s efficiency. Need more help? Give Cowboys Heating and Air a call and we will send someone out to check your filter, replace it for you and show you what to look for in order to keep your furnace running in top condition!