Picking out the correct 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 crucial part in keeping its system running safely, efficiently and for a long time.

A clogged furnace filter loses its effectiveness, permitting potentially harmful particles to circulate through your home. It also limits airflow, which can damage your furnace and shorten its life span.

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

The health of your family is important to the heating and cooling specialists at Booneville Heating & Cooling. We've long worked with an eye on bettering indoor air quality in Booneville. Here, we’ve answered common questions about HVAC filters, including that especially tricky question of what direction do you point a filter in your furnace or air conditioner?

How Often to Replace the Air Filter in a Furnace

It's important to replace dirty air filters in a furnace or air conditioner periodically. Dirty filters cause the system to worker harder than it should because it takes more energy to pull air through the plugged-up filter.

Officials suggest examining your furnace filter monthly and replacing it if it’s dirty. You’ll know if the filter needs to be changed because it will coated with dirt or dust. People who have pets will probably want to replace their furnace air filter more often, because a quality air filter will trap pet hair circulating in a home.

Where Is the Air Filter in My Furnace?

In general, a furnace air filter is normally found in the return air duct or blower compartment before the return air goes back into the furnace. This ensures 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 located on the right, left, bottom or in some cases, inside the furnace. It's generally housed within a slot, frame or cabinet for convenient access and replacement. Always refer to your furnace's owner manual for information about filter location of the furnace in your home.

Is a Furnace Filter the Same as an Air Filter?

The straightforward answer is, yes. In HVAC, a furnace filter and an air filter or AC filter are essentially the same. While they might be called different things based on the current season— hot or cold—they are all filters that clean the air in your HVAC system.

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

What Is the MERV Rating System and What MERV Rating Should I Have?

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

MERV is short for Minimum Efficiency Reporting Values. The MERV rating calculates the effectiveness of air filters at trapping airborne molecules. The rating scale ranges from 1 to 20, with higher numbers indicating enhanced capabilities to filter tinier particles.

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

Which Way to Put the Air Filter in a Furnace or Air Conditioning System

Putting an air filter in a furnace or air conditioner properly is crucial for the efficient operation of the system. 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 AC, which is the direction of the airflow. If you're not sure about the airflow direction, remember that air always moves from the return duct towards the heat or cooling source. Therefore, be sure that the arrow points in the direction of the furnace or AC.

Many people struggle with which direction to point their air filter. To help remember, consider taking a quick picture with your mobile 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 point. A perfect time to inquire about this is during a routine furnace maintenance visit.

Changing Your Furnace's Air Filter

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

  1. Turn off your furnace: Be sure to switch off your furnace before beginning the process.
  2. Find the furnace filter: Typically, the filter is found inside the furnace or in the air return vent. Make note of which direction the arrow points on the filter, because you’ll want the arrow on the new filter to point the same way.
  3. Remove 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 you keep track of when it's time for you to change it again.
  5. Put in new filter: Put in the new filter with the arrow pointing toward the furnace, which is the direction of airflow and should be the same direction the arrow pointed on the dirty filter you just removed.
  6. Secure the filter: Make sure the new filter fits correctly and close any latches or clips that secure it in the compartment.
  7. Turn on your furnace: Once the new filter is completely in place, you can turn your furnace back on.

Can a Dirty Air Filter Damage My Furnace?

The short answer is, yes, a dirty air filter can cause a furnace to quit working or limit its lifespan. Changing your furnace or air conditioner filter is one of the best things you can do to keep your system working efficiently.