Choosing the proper 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.
A clogged furnace filter loses its effectiveness, allowing potentially harmful particles to move through your home. It also limits airflow, which can damage your furnace and shorten its life span.
Ensuring 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 excellent indoor air quality for your household.
The health of your family is important to the heating and cooling professionals at Ilten's. We've long focused on bettering indoor air quality in Cedar Rapids. 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?
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 suggest checking your furnace filter monthly and replacing it if it’s dirty. You’ll know if your filter needs changing because it will filled with dirt or dust. Homeowners who have pets that shed will very likely want to replace their furnace air filter more often, because a good air filter will trap pet hair circulating in a home.
Locating Your Furnace's Air Filter
In general, a furnace air filter is commonly installed in the return air duct or blower compartment before the return air goes back into the furnace. This ensures air flowing into the system is filtered before it moves through the furnace components and is heated.
Depending on the type of furnace, the filter may be positioned on the right, left, bottom or in some cases, inside the furnace. It's typically housed inside of a slot, frame or cabinet for convenient access and replacement. Always refer to your furnace's owner manual for important information about filter location of the furnace in your home.
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 AC filter are basically the same. 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 contaminants 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 a MERV Rating 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 determining the level of filtration that you need. One method to do this is by picking an appropriate MERV rating for your needs.
MERV is an abbreviation for Minimum Efficiency Reporting Values. The MERV rating indicates the effectiveness of air filters at trapping airborne molecules. The rating scale ranges from 1 to 20, with higher numbers indicating the power to filter small particles.
Experts say a filter with a MERV rating between 8 and 13 offers an ideal balance between having healthy indoor air quality without unnecessarily restricting airflow. However, people with specific health conditions may need to use a filter with a higher MERV rating.
Where to Insert the Air Filter in a Furnace or Air Conditioning System
Positioning an air filter in a furnace or air conditioner properly is crucial for the efficient operation of the system. Air filters are supposed to face a specific 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 at the furnace or AC, which is the direction of the airflow. If you're unsure about the airflow direction, it may be helpful to remember that air always moves from the return duct towards the heat or cooling source. Therefore, make certain the arrow points at the furnace or air conditioning unit.
Many people have difficulty remembering which direction to install an air filter. To help remember, consider taking a 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 perfect time to ask about this is during a routine furnace maintenance visit.
How to Replace Your Furnace Air Filter
Replacing the filter on your furnace or air conditioning system is a simple process. Here is a step-by-step list of how to remove a dirty air filter and exchange it for a new one:
- Turn off your furnace: Make a point to shut off your furnace before starting the process.
- Look for the furnace filter: Typically, the filter is located inside 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 clean filter to point the same way.
- Take out the old filter: Be careful 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 you keep track of when it's time for you to change it again.
- Insert 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.
- Secure the filter: Make sure the new filter fits securely and close any latches or clips that secure it in the compartment.
- Turn on your furnace: Once the new filter is safely installed, you can turn your furnace back on.
Can a Dirty Air Filter Cause Problems for a Furnace?
The shortest answer is, yes, a dirty air filter can cause a furnace to stop working or shorten its lifespan. Changing your furnace or air conditioning filter is one of the best things you can do to keep your system running efficiently.