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 critical function in keeping its system running 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 decrease its life span.

Ensuring your furnace uses a clean filter that is appropriate for your needs is not only about keeping your furnace working efficiently. It’s also about delivering healthy indoor air quality for your residence.

Your health is important to the HVAC specialists at Durable Service. We've long been dedicated to enhancing indoor air quality in Holdrege. Here, we’ve answered frequent questions about HVAC filters, including that very 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. Dirt-clogged filters cause the system to worker harder than it should because it takes extra effort to move air through the plugged-up filter.

Officials recommend checking your furnace filter every 30 days and replacing it if it’s dirty. You’ll know if it is dirty because it will filled with dirt or dust. Homeowners who have pets that shed will probably want to replace their furnace air filter more often, because a good 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 found in the return air duct or blower compartment before the return air goes back into the furnace. This is so air entering the system is filtered before it passes 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, within the furnace. It's generally housed inside of a slot, frame or cabinet for simple access and replacement. Always refer to your furnace's owner manual for information about filter location of your particular brand and model of furnace.

Is a Furnace Filter the Same as an Air Filter?

The easy answer is, yes. In HVAC, a furnace filter and an air filter or air conditioner 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 HVAC system.

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

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

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

MERV is an abbreviation for Minimum Efficiency Reporting Values. The MERV rating measures the effectiveness of air filters at trapping airborne contaminants. The rating scale ranges from 1 to 20, with bigger numbers indicating a greater ability to filter smaller 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 some 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 Conditioning System

Putting an air filter in a furnace or air conditioner the proper way is necessary for the efficient operation of the unit. 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 placed in the unit with this arrow pointing toward the furnace or air conditioning unit, 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, make certain the arrow points in the direction of the furnace or air conditioning unit.

Many people have difficulty remembering which direction to face their system's air filter. To help remember, consider snapping a quick photo 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 call.

How to Change a Furnace Air Filter

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

  1. Turn off your furnace: Make sure to shut off your furnace before starting up the process.
  2. Locate the furnace filter: Typically, the filter is positioned within 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 new filter to point the same way.
  3. Take out the old filter: Be diligent not to knock out any dust or particles.
  4. Record 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 old filter you are replacing.
  6. Secure the filter: Make sure the new filter fits correctly and close any latches or clips that lock it in place.
  7. Turn on your furnace: Once the replacement filter is completely secured, you can turn your furnace back on.

Can a Dirty Air Filter Damage My Furnace?

The simple 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 running efficiently.