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

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

Making certain 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 delivering healthy indoor air quality for your residence.

Your health is important to the heating professionals at I-Deal HVAC. We've long worked with an eye on enhancing indoor air quality in Albuquerque. 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?

It is critical 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 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 coated with dirt or dust. Homeowners 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.

Where Is the Air Filter in My Furnace?

In general, a furnace air filter is commonly located in the return air duct or blower compartment before the return air goes back into 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, on the inside of the furnace. It's typically housed in a slot, frame or cabinet for easy access and replacement. Always refer to your furnace's owner manual for details concerning filter location of your furnace.

Are Air Filters and Furnace Filters the Same Thing?

The easy answer is, yes. In HVAC, a furnace filter and an air filter or air conditioning filter are basically the same. While they might be called different things based on the current season— warm or chilly months—they are all filters that clean the air in your HVAC system.

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

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

Once you track down your old furnace filter and determine when it should be replaced, it’s time to select a replacement. That means determining the level of filtration that you need. One way to do that is by selecting 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 contaminants. The rating scale ranges from 1 to 20, with greater numbers indicating a greater ability to filter tinier particles.

Experts say a filter with a MERV rating between 8 and 13 offers an ideal balance between having healthy indoor air quality without needlessly restricting airflow. However, people with certain health conditions might need a a higher MERV rating.

How to Place the Air Filter in a Furnace or Air Conditioner

Positioning an air filter in a furnace or air conditioner the proper way is important for the efficient operation of the unit. Air filters are designed to be installed in a particular direction, indicated by an arrow written on the side of the filter frame. The filter should be installed with this arrow pointing in the direction of the furnace or air conditioning unit, which is the direction of the airflow. If you're not sure about the airflow direction, it may be helpful to 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 air conditioning unit.

Many people have difficulty remembering which direction to point their system's air filter. To help remember, consider taking a 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 go. A great time to ask about this is during a regular furnace maintenance visit.

How to Replace Your Furnace Air Filter

Replacing 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 replace it with a new one:

  1. Turn off your furnace: Be sure to shut 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. Make note of which direction the arrow points on the filter, because you’ll want the arrow on the clean filter to point similarly.
  3. Take out the old filter: Be careful not to knock out any dust or dirt.
  4. Note the date: Write down the date you changed filters on the new filter's frame. This will make it easier to 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 nicely and close any latches or clips that lock it in the unit.
  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 short answer is, yes, a dirty air filter can cause a furnace to stop working or decrease its lifespan. Changing your furnace or AC filter is one of the simplest things you can do to keep your system running effectively.