Selecting the correct 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 crucial part in keeping its system running safely, efficiently and for a long time.

A dirty furnace filter loses its effectiveness, allowing potentially harmful particles to move through your home. It also restricts airflow, which can damage your furnace and reduce its life span.

Ensuring your furnace uses a clean filter that is suitable for your needs is not just about keeping your furnace running efficiently. It’s also about creating good indoor air quality for your home.

The quality of the air your family breathes is important to the heating specialists at Luikart Heating & Cooling. We've long worked with an eye on bettering indoor air quality in Newark. 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?

How Often to Replace the Air Filter in a Furnace

It's vital to replace dirty air filters in a furnace or air conditioner periodically. Soiled filters cause the system to worker harder than it should because it takes extra work to move air through the plugged-up filter.

Officials suggest examining your furnace filter every 30 days and replacing it if it’s dirty. You’ll know if your filter needs changing because it will filled with dirt or dust. People who have pets will likely need to replace their furnace air filter more often, because an effective 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 found in the return air duct or blower compartment before the return air reaches the furnace. This makes sure 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 in a slot, frame or cabinet for simple access and replacement. Always refer to your furnace's owner manual for information regarding filter location of your particular brand and model of furnace.

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 conditioner filter are essentially identical. 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 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 certain the air flowing through your home is clean and safe.

What Is a MERV Rating and What MERV Rating Do I Need?

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

MERV is an abbreviation for Minimum Efficiency Reporting Values. The MERV rating calculates the effectiveness of air filters at trapping airborne particles. 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 needlessly restricting airflow. However, people with some health conditions may need a a higher MERV rating.

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

Putting an air filter in a furnace or air conditioner the proper way is necessary for the efficient operation of the system. Air filters are designed to be installed in a specific direction, indicated by an arrow written 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 unsure about the airflow direction, try to 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 AC.

Many people have difficulty remembering which direction to install an air filter. To help remember, consider taking a quick picture with your mobile 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 be installed. A handy time to do this is during a scheduled furnace maintenance visit.

How to Change a Furnace Air Filter

Replacing the filter on your furnace or air conditioning system is an easy process. Here is a step-by-step breakdown of how to take out a dirty air filter and replace it with a new one:

  1. 1. Turn off your furnace: Be sure to turn off your furnace before starting up the process.
  2. Look for the furnace filter: Typically, the filter is positioned in 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 new filter to point in the same direction.
  3. Slide out the old filter: Be diligent not to knock out any dust or debris.
  4. Document the date: Write down the date of replacement on the new filter's frame. This will help your family keep track of when it's time for the next change.
  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 correctly and close any latches or clips that secure it in place.
  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 Cause a Furnace Not to Work?

The simple 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 best things you can do to keep your system operating effectively.