Picking out the proper furnace filter and changing it when it is dirty is as important to your HVAC system as changing the oil is to your car. Each plays a vital role in keeping its system running safely, efficiently and for a long time.

An overused furnace filter loses its effectiveness, allowing potentially harmful particles to circulate through your home. It also slows airflow, which can damage your furnace and shorten its life span.

Making sure your furnace uses a clean filter that is appropriate for your needs is not merely about keeping your furnace running efficiently. It’s also about delivering healthy indoor air quality for your household.

Your health is important to the heating professionals at Dearing's Service & Solutions. We've long focused on enhancing indoor air quality in Huntingburg. Here, we’ve answered frequent questions about HVAC filters, including that very 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 vital to replace dirty air filters in a furnace or air conditioner routinely. Dirt-clogged filters cause the system to worker harder than it should because it takes extra work to pull 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 be gray or black from dirt or dust. Those who have pets will likely need to replace their furnace air filter more often, because a good air filter will trap pet hair circulating in a home.

Locating Your Furnace's Air Filter

In general, a furnace air filter is normally found in the return air duct or blower compartment before the return air gets to the furnace. This is so air entering 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 usually housed in a slot, frame or cabinet for simple access and replacement. Always refer to your furnace's owner manual for facts regarding filter location of your furnace.

Are Air Filters and Furnace Filters the Same Thing?

The simple answer is, yes. In HVAC, a furnace filter and an air filter or air conditioner filter are essentially the same thing. While people may call them different things based on the current season— summer or winter—they are all filters that clean the air in your HVAC system.

They each remove dust, allergens, bacteria and other airborne debris from the air that is drawn into the furnace and air conditioning system, making certain the air distributed throughout your home is clean and safe.

What Are MERV Ratings and What MERV Rating Do I Need?

Once you find your old furnace filter and figure out when it should be substituted for a clean one, it’s time to choose a replacement. That means deciding on the level of filtration that you need. One approach to this is by selecting an appropriate MERV rating for your needs.

MERV stands for Minimum Efficiency Reporting Values. The MERV rating indicates the effectiveness of air filters at trapping airborne particles. The rating scale ranges from 1 to 20, with greater numbers indicating enhanced capabilities to filter small particles.

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

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

Putting an air filter in a furnace or air conditioner properly is important for the efficient operation of the unit. Air filters are supposed to face a specific direction, indicated by an arrow written on the side of the filter frame. The filter should be placed in the unit with this arrow pointing in the direction of the furnace or AC, which is the direction of the airflow. If you're doubtful about the airflow direction, remember that air always moves from the return duct and then to the heat or cooling source. Therefore, make sure the arrow points toward the furnace or air conditioner.

Many people have difficulty remembering which direction to face an air filter. To help remember, consider taking a quick picture with your cellular phone after the filter has been properly 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 point. A handy time to ask about this is during a routine furnace maintenance appointment.

How to Change a Furnace Air Filter

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

  1. Turn off your furnace: Be sure to turn off your furnace before starting the process.
  2. Find the furnace filter: Typically, the filter is located in the furnace or in the air return vent. Take note of which direction the arrow points on the filter, because you’ll want the arrow on the clean filter to point the same way.
  3. Take out the old filter: Be careful not to knock out any dust or particles.
  4. Record the date: Write down the date you changed filters on the new filter's frame. This will help your family keep track of when it's time for another replacement.
  5. Slide in new filter: Put in the new filter with the arrow pointing at the furnace, which is the direction of airflow and should be the same direction the arrow pointed on your last filter.
  6. Secure the filter: Make sure the new filter fits securely and close any latches or clips that hold it in the unit.
  7. Turn on your furnace: Once the new filter is completely secured, you can turn your furnace back on.

Will a Dirty Air Filter Damage My Furnace?

The simple answer is, yes, a dirty air filter can cause a furnace to stop working or decrease its lifespan. Changing your furnace or air conditioning filter is one of the simplest things you can do to keep your system running effectively.