Selecting the ideal furnace filter and changing it when it becomes dirty is as important to your HVAC system as changing the oil is to your car. Each plays a critical function in keeping its system running safely, efficiently and for a long time.

A dirty furnace filter loses its effectiveness, enabling potentially harmful particles to circulate through your home. It also restricts airflow, which can damage your furnace and decrease its life span.

Making sure your furnace uses a clean filter that is ideal for your needs is not merely about keeping your furnace operating efficiently. It’s also about providing excellent indoor air quality for your residence.

The health of your family is important to the heating professionals at Covington Air Systems. We've long been dedicated to enhancing indoor air quality in Covington. Here, we’ve answered frequent questions about HVAC filters, including that especially tricky question of what direction do you point a filter in your furnace or air conditioner?

When to Replace the Air Filter in Your Furnace

It is important to replace dirty air filters in a furnace or air conditioner regularly. Soiled filters cause the system to worker harder than it should because it takes extra work to force air through the plugged-up filter.

Officials recommend inspecting your furnace filter every 30 days and replacing it if it’s dirty. You’ll know if your filter needs changing because it will filled with dirt or dust. People who have pets that shed will probably want to replace their furnace air filter more often, because a quality air filter will trap pet hair circulating in a home.

Locating Your Furnace's Air Filter

In general, a furnace air filter is commonly installed in the return air duct or blower compartment before the return air reaches the furnace. This makes sure air flowing into the system is filtered before it goes through the furnace components and is heated.

Depending on the furnace model, the filter may be found on the right, left, bottom or in some cases, within the furnace. It's typically housed within a slot, frame or cabinet for easy access and replacement. Always refer to your furnace's owner manual for information regarding filter location of your furnace.

Is My Furnace Filter Just a Type of Air Filter?

The straightforward answer is, yes. In HVAC, a furnace filter and an air filter or air conditioning filter are effectively the same. While people may call them different things based on the current season— hot or cold—they are all filters that clean the air in your residence.

They each get rid of dust, allergens, bacteria and other contaminants from the air that is drawn into the furnace and air conditioning system, making sure the air distributed throughout your home is clean and safe.

What Is a MERV Rating and What Rating Is Best for Me?

Once you locate your old furnace filter and figure out when it should be substituted for a clean one, it’s time to select a replacement. That means picking the level of filtration that you need. One way to do that is by selecting an appropriate MERV rating for your needs.

MERV is an abbreviation for Minimum Efficiency Reporting Values. The MERV rating calculates the effectiveness of air filters at trapping airborne contaminants. The rating scale ranges from 1 to 20, with bigger numbers indicating enhanced capabilities to filter small particles.

Experts say a filter with a MERV rating between 8 and 13 offers an ideal balance between having good indoor air quality without overly restricting airflow. However, people with specific health conditions might need to purchase a filters with a higher MERV rating.

How to Place the Air Filter in a Furnace or Air Conditioning System

Installing an air filter in a furnace or air conditioner correctly is crucial for the efficient operation of the unit. Air filters are designed to be installed in a specific direction, indicated by an arrow written on the side of the filter frame. The filter should be installed with this arrow pointing toward the furnace or air conditioning unit, which is the direction of the airflow. If you're unsure about the airflow direction, it may be helpful to remember that air always moves from the return duct to the heat or cooling source. Therefore, be sure that the arrow points at the furnace or AC.

Many people have difficulty remembering which direction to install an air filter. To help remember, consider taking a quick picture with your cellular phone after the filter has been accurately installed by a professional. Or, you also could ask a technician to use a marker to write on the outside of your furnace which direction the filter should be installed. A handy time to inquire about this is during a scheduled furnace maintenance appointment.

How to Replace Your Furnace Air Filter

Replacing the filter on your furnace or AC is a simple process. Here is a step-by-step rundown of how to retreive a dirty air filter and exchange it for a new one:

  1. Turn off your furnace: Make a point to turn off your furnace before starting the process.
  2. Locate the furnace filter: Typically, the filter is found within the furnace or in the air return vent. Make a mental note or write down which direction the arrow points on the filter, because you’ll want the arrow on the clean filter to point in the same direction.
  3. Remove the old filter: Be careful not to knock out any dust or particles.
  4. Note the date: Write down the date of replacement on the new filter's frame. This will help you keep track of when it's time for another replacement.
  5. Put in new filter: Put in the new filter with the arrow pointing in the direction of the furnace, which is the direction of airflow and should be the same direction the arrow pointed on the old filter you are replacing.
  6. Secure the filter: Make sure the new filter fits correctly and close any latches or clips that hold it in the compartment.
  7. Turn on your furnace: Once the clean filter is completely in place, you can turn your furnace back on.

Will a Dirty Air Filter Cause a Furnace Not to Work?

The shortest answer is, yes, a dirty air filter can cause a furnace to cease working or limit its lifespan. Changing your furnace or air conditioning filter is one of the simplest things you can do to keep your system working efficiently.