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 vital role in keeping its system operating safely, efficiently and for a long time.

An overused furnace filter loses its effectiveness, allowing potentially harmful particles to flow through your home. It also restricts 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 working efficiently. It’s also about providing good indoor air quality for your residence.

The quality of the air your family breathes is important to the HVAC professionals at ACS Heating and Air Conditioning. We've long worked with an eye on improving indoor air quality in Tucker. Here, we’ve answered common 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 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 extra work to force air through the plugged-up filter.

Officials advise examining your furnace filter every month and replacing it if it’s dirty. You’ll know if it is dirty because it will filled with dirt or dust. People who have pets will probably need to replace their furnace air filter more often, because a quality air filter will trap pet hair circulating in a home.

How to Find the Furnace's Air Filter

In general, a furnace air filter is normally located 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 goes through the furnace components and is heated.

Depending on the furnace brand, the filter may be found on the right, left, bottom or in some cases, within the furnace. It's typically housed inside of a slot, frame or cabinet for convenient access and replacement. Always refer to your furnace's owner manual for information concerning 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 conditioning filter are basically the same thing. While people may call them different things based on the current season— warm or chilly months—they are all filters that clean the air in your residence.

They each eliminate dust, allergens, bacteria and other particulates 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 Rating Is Best for Me?

Once you track down your old furnace filter and decide when it should be replaced, it’s time to pick a replacement. That means picking the level of filtration that you need. One approach to this 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 higher numbers indicating the power to filter tinier particles.

Experts say a filter with a MERV rating between 8 and 13 offers an ideal balance between having adequate indoor air quality without overly restricting airflow. However, people with specific health conditions may need a 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 heating or cooling system. Air filters have a particular direction, indicated by an arrow located on the side of the filter frame. The filter should be put in with this arrow pointing toward 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 at the furnace or AC.

Many people have difficulty remembering which direction to point their system's air filter. To help remember, consider taking a quick picture with your cell 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 handy time to inquire about this is during a scheduled furnace maintenance visit.

How to Replace Your Furnace Air Filter

Replacing the filter on your furnace or air conditioner is an easy 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: Make a point to switch off your furnace before starting the process.
  2. Locate the furnace filter: Typically, the filter is positioned inside 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. Slide out the old filter: Be diligent not to knock out any dust or particles.
  4. Note the date: Write down the date you replaced the filter on the new filter's frame. This will help your family keep track of when it's time for the next change.
  5. Insert 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 nicely and close any latches or clips that hold it in place.
  7. Turn on your furnace: Once the new filter is properly installed, 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 quit working or limit its lifespan. Changing your furnace or air conditioner filter is one of the simplest things you can do to keep your system running correctly.