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

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

Making certain your furnace uses a clean filter that is ideal for your needs is not just about keeping your furnace working efficiently. It’s also about providing healthy indoor air quality for your household.

The quality of the air your family breathes is important to the heating specialists at MPC Heating & Cooling. We've long focused on bettering indoor air quality in Chadron. Here, we’ve answered frequent questions about HVAC filters, including that particularly tricky question of what direction do you point a filter in your furnace or air conditioner?

When Should I Replace My Furnace Air Filter?

Experts stress it's vital to replace dirty air filters in a furnace or air conditioner regularly. Dirt-clogged filters cause the system to worker harder than it should because it takes extra effort to pull air through the plugged-up filter.

Officials suggest checking your furnace filter every 30 days and replacing it if it’s dirty. You’ll know if your filter needs changing because it will coated with dirt or dust. Those who have pets will very likely have 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 usually installed in the return air duct or blower compartment before the return air reaches the furnace. This ensures air flowing into the system is filtered before it moves through the furnace components and is heated.

Depending on the furnace brand, the filter may be positioned on the right, left, bottom or in some cases, inside the furnace. It's usually housed inside of a slot, frame or cabinet for easy access and replacement. Always refer to your furnace's owner manual for information about filter location of the furnace in your home.

Are Air Filters and Furnace Filters the Same Thing?

The straightforward answer is, yes. In HVAC, a furnace filter and an air filter or air conditioner filter are basically identical. While people might refer to them differently based on the current season— summer or winter—they are all filters that clean the air in your residence.

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

What Is the MERV Rating System and What MERV Rating Do I Need?

Once you find your old furnace filter and decide when it should be replaced, it’s time to select a replacement. That means picking the level of filtration that you need. One method to do this is by choosing an appropriate MERV rating for your needs.

MERV is an abbreviation for Minimum Efficiency Reporting Values. The MERV rating measures the effectiveness of air filters at trapping airborne molecules. The rating scale ranges from 1 to 20, with higher numbers indicating a greater ability to filter smaller 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 certain health conditions could need to purchase a filters with a higher MERV rating.

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

Positioning an air filter in a furnace or air conditioner correctly is important for the efficient operation of the heating or cooling system. Air filters have a particular direction, indicated by an arrow written on the side of the filter frame. The filter should be installed with this arrow pointing at the furnace or air conditioning unit, which is the direction of the airflow. If you're doubtful about the airflow direction, try to remember that air always moves from the return duct to the heat or cooling source. Therefore, make certain the arrow points toward the furnace or AC.

Many people have difficulty remembering which direction to point their air filter. To help remember, consider taking a quick picture with your cell phone after the filter has been correctly 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 great time to do this is during a regular furnace maintenance appointment.

Changing Your Furnace's Air Filter

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

  1. Turn off your furnace: Make sure to shut off your furnace before starting up the process.
  2. Find the furnace filter: Typically, the filter is positioned 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. Remove the old filter: Be mindful not to knock out any dust or dirt.
  4. Note the date: Write down the date of replacement on the new filter's frame. This will help your family keep track of when it's time for the next change.
  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 securely and close any latches or clips that secure it in place.
  7. Turn on your furnace: Once the clean filter is properly in place, you can turn your furnace back on.

Will a Dirty Air Filter Damage My Furnace?

The short answer is, yes, a dirty air filter can cause a furnace to cease working or limit its lifespan. Changing your furnace or AC filter is one of the easiest things you can do to keep your system working correctly.