Picking out the right 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 function in keeping its system running safely, efficiently and for a long time.

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

Ensuring your furnace uses a clean filter that is suitable for your needs is not merely about keeping your furnace operating 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 Speedy Air Conditioning. We've long focused on improving indoor air quality in Naples. Here, we’ve answered common 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. Dirty filters cause the system to worker harder than it should because it takes more energy to force air through the plugged-up filter.

Officials suggest inspecting your furnace filter every month and replacing it if it’s dirty. You’ll know if the filter needs to be changed because it will be gray or black from dirt or dust. People who have pets will probably have to replace their furnace air filter more often, because a good 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 usually found in the return air duct or blower compartment before the return air gets to the furnace. This makes sure air being pulled into the system is filtered before it goes through the furnace components and is heated.

Depending on the furnace model, the filter may be positioned on the right, left, bottom or in some cases, within the furnace. It's typically housed within a slot, frame or cabinet for convenient access and replacement. Always refer to your furnace's owner manual for facts 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 air conditioning filter are basically the same thing. While people might refer to them differently based on the current season— warm or chilly months—they are all filters that clean the air in your home.

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

What Is a MERV Rating and What MERV Rating Should I Have?

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

MERV is an abbreviation 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 higher numbers indicating a greater ability to filter small particles.

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

Which Way to Put the Air Filter in a Furnace or Air Conditioner

Positioning an air filter in a furnace or air conditioner the proper way is crucial for the efficient operation of the heating or cooling system. Air filters are supposed to face a certain 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 doubtful about the airflow direction, it may be helpful to remember that air always moves from the return duct and then to 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 install their system's 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 great time to ask about this is during a routine furnace maintenance call.

Changing Your Furnace's Air Filter

Replacing the filter on your furnace or AC is a quick and easy process. Here is a step-by-step list of how to retreive a dirty air filter and replace it with a new one:

  1. Turn off your furnace: Make a point to switch 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 new filter to point the same way.
  3. Take out the old filter: Be mindful not to knock out any dust or debris.
  4. Record the date: Write down the date of replacement on the new filter's frame. This will make it easier to keep track of when it's time for you to change it again.
  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 correctly and close any latches or clips that hold it in the compartment.
  7. Turn on your furnace: Once the new filter is properly secured, you can turn your furnace back on.

Can a Dirty Air Filter Cause Problems for a Furnace?

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