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 vital function in keeping its system running safely, efficiently and for a long time.

A clogged furnace filter loses its effectiveness, allowing potentially harmful particles to flow through your home. It also limits 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 working efficiently. It’s also about creating excellent indoor air quality for your home.

Your health is important to the HVAC pros at Premium Air Services LLC. We've long been dedicated to enhancing indoor air quality in Tomball. 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?

When Should I Replace My Furnace Air Filter?

Experts stress it's 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 extra work to move 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 your filter needs changing because it will coated with dirt or dust. Homeowners who have pets that shed will very likely need 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 normally found in the return air duct or blower compartment before the return air reaches the furnace. This is so air being pulled into the system is filtered before it moves 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 generally housed within a slot, frame or cabinet for convenient access and replacement. Always refer to your furnace's owner manual for important information regarding filter location of your particular brand and model of 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 conditioner filter are effectively the same. While people may call them different things based on the current season— hot or cold—they are all filters that clean the air in your residence.

They each get rid of 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 changed, it’s time to choose 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 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 greater 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 needlessly restricting airflow. However, people with some health conditions could need to purchase a filters with a higher MERV rating.

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

Installing an air filter in a furnace or air conditioner properly is important for the efficient operation of the system. Air filters have a specific direction, indicated by an arrow located 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 and then to the heat or cooling source. Therefore, make certain the arrow points toward the furnace or air conditioner.

Many people are confused by which direction to install their air filter. To help remember, consider taking a quick picture with your cellular phone after the filter has been properly 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 scheduled furnace maintenance appointment.

How to Replace Your Furnace Air Filter

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

  1. Turn off your furnace: Make sure to switch 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. Make a mental note or write down which direction the arrow points on the filter, because you’ll want the arrow on the replacement filter to point similarly.
  3. Slide out the old filter: Be diligent not to knock out any dust or particles.
  4. Document the date: Write down the date of replacement on the new filter's frame. This will help you keep track of when it's time for another replacement.
  5. Slide in new filter: Put in the new filter with the arrow pointing at 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 securely and close any latches or clips that secure it in the compartment.
  7. Turn on your furnace: Once the replacement filter is properly in place, you can turn your furnace back on.

Will a Dirty Air Filter Damage My Furnace?

The shortest answer is, yes, a dirty air filter can cause a furnace to quit working or decrease its lifespan. Changing your furnace or AC filter is one of the easiest things you can do to keep your system operating efficiently.