Choosing the ideal 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 operating safely, efficiently and for a long time.
A clogged furnace filter loses its effectiveness, enabling potentially harmful particles to move through your home. It also slows airflow, which can damage your furnace and decrease its life span.
Making sure your furnace uses a clean filter that is ideal for your needs is not just about keeping your furnace working efficiently. It’s also about creating healthy indoor air quality for your household.
Your health is important to the HVAC pros at AZ Air Conditioning and Heating. We've long been dedicated to improving indoor air quality in Los Angeles. Here, we’ve answered frequent 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?
Experts stress it's vital to replace dirty air filters in a furnace or air conditioner routinely. Dirty filters cause the system to worker harder than it should because it takes extra effort 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 it is dirty because it will be gray or black from dirt or dust. People who have pets that shed will likely have 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 commonly located in the return air duct or blower compartment before the return air goes back into the furnace. This makes sure air flowing into the system is filtered before it goes 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, inside 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 facts concerning filter location of your particular brand and model of furnace.
Is My Furnace Filter Just a Type of Air Filter?
The simple 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 home.
They each get rid of dust, allergens, bacteria and other particulates from the air that is drawn into the furnace and air conditioning system, making certain the air distributed 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 figure out when it should be replaced, it’s time to pick a replacement. That means determining the level of filtration that you need. One way to do that is by selecting an appropriate MERV rating for your needs.
MERV is short for Minimum Efficiency Reporting Values. The MERV rating indicates the effectiveness of air filters at trapping airborne contaminants. The rating scale ranges from 1 to 20, with higher numbers indicating enhanced capabilities to filter smaller particles.
Experts say a filter with a MERV rating between 8 and 13 offers an ideal balance between having adequate indoor air quality without unnecessarily restricting airflow. However, people with some health conditions might need to purchase a filters with a higher MERV rating.
How to Place the Air Filter in a Furnace or AC Unit
Installing an air filter in a furnace or air conditioner correctly 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 placed in the unit with this arrow pointing toward the furnace or AC, which is the direction of the airflow. If you're not sure about the airflow direction, it may be helpful to remember that air always moves from the return duct to the heat or cooling source. Therefore, make sure the arrow points toward the furnace or air conditioning unit.
Many people struggle with which direction to point their 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 point. A handy time to inquire about this is during a regular furnace maintenance call.
How to Replace Your Furnace Air Filter
Switching out the filter on your furnace or air conditioning system 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:
- Turn off your furnace: Make a point to turn off your furnace before starting up the process.
- Locate the furnace filter: Typically, the filter is positioned within 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 replacement filter to point similarly.
- Slide out the old filter: Be diligent not to knock out any dust or particles.
- 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 another replacement.
- Slide in 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.
- Secure the filter: Make sure the new filter fits securely and close any latches or clips that secure it in place.
- Turn on your furnace: Once the new filter is safely in place, 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 decrease its lifespan. Changing your furnace or AC filter is one of the easiest things you can do to keep your system working correctly.