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 crucial role in keeping its system running safely, efficiently and for a long time.
An overused furnace filter loses its effectiveness, allowing potentially harmful particles to flow through your home. It also restricts airflow, which can damage your furnace and shorten its life span.
Making sure your furnace uses a clean filter that is suitable for your needs is not merely about keeping your furnace working efficiently. It’s also about creating excellent indoor air quality for your household.
The quality of the air your family breathes is important to the HVAC pros at B & B Heating & Cooling. We've long worked with an eye on bettering indoor air quality in Florissant and St. Charles. Here, we’ve answered frequent questions about HVAC filters, including that especially 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 is important to replace dirty air filters in a furnace or air conditioner regularly. 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 advise 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 be gray or black from dirt or dust. Those who have pets that shed will very likely want 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 normally found in the return air duct or blower compartment before the return air gets to the furnace. This makes sure air flowing into the system is filtered before it passes through the furnace components and is heated.
Depending on the type of furnace, the filter may be found on the right, left, bottom or in some cases, on the inside of 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 details concerning filter location of your particular brand and model of furnace.
Is My Furnace Filter Just a Type of Air Filter?
The easy answer is, yes. In HVAC, a furnace filter and an air filter or AC filter are basically identical. While they might be called different things 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 airborne debris 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 Are MERV Ratings 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 determining the level of filtration that you need. One approach to this 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 particles. The rating scale ranges from 1 to 20, with higher numbers indicating enhanced capabilities to filter small particles.
Experts say a filter with a MERV rating between 8 and 13 offers an ideal balance between having good indoor air quality without unnecessarily restricting airflow. However, people with certain health conditions might need a a higher MERV rating.
Which Way to Put the Air Filter in a Furnace or Air Conditioner
Installing an air filter in a furnace or air conditioner correctly is necessary for the efficient operation of the system. Air filters are designed to be installed in a specific direction, indicated by an arrow printed on the side of the filter frame. The filter should be placed in the unit 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, try to remember that air always moves from the return duct and then to the heat or cooling source. Therefore, make sure the arrow points at the furnace or air conditioner.
Many people struggle with 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 correctly 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 perfect time to inquire about this is during a regular furnace maintenance appointment.
Changing Your Furnace's Air Filter
Replacing the filter on your furnace or AC is an easy process. Here is a step-by-step list 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.
- Find the furnace filter: Typically, the filter is located within 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 replacement filter to point the same way.
- Remove the old filter: Be careful not to knock out any dust or debris.
- Document the date: Write down the date you changed filters on the new filter's frame. This will help your family keep track of when it's time for the next change.
- 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.
- Secure the filter: Make sure the new filter fits correctly 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.
Can 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 simplest things you can do to keep your system working correctly.