Picking out the right furnace filter and changing it when it gets dirty is as important to your HVAC system as changing the oil is to your car. Each plays a critical part in keeping its system operating safely, efficiently and for a long time.
An overused furnace filter loses its effectiveness, permitting potentially harmful particles to move through your home. It also slows airflow, which can damage your furnace and reduce its life span.
Making certain your furnace uses a clean filter that is appropriate for your needs is not merely about keeping your furnace running efficiently. It’s also about providing excellent indoor air quality for your residence.
Your health is important to the heating and cooling professionals at Contra Costa Heating & AC. We've long worked with an eye on improving indoor air quality in The Bay Area. 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 is important to replace dirty air filters in a furnace or air conditioner regularly. Dirty filters cause the system to worker harder than it should because it takes more energy to force air through the plugged-up filter.
Officials advise checking your furnace filter monthly and replacing it if it’s dirty. You’ll know if it is dirty because it will coated with dirt or dust. People who have pets will probably need 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 usually located in the return air duct or blower compartment before the return air gets to the furnace. This ensures air being pulled into the system is filtered before it passes 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 typically housed within a slot, frame or cabinet for easy access and replacement. Always refer to your furnace's owner manual for important information concerning 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 air conditioning filter are effectively identical. While people might refer to them differently based on the current season— hot or cold—they are all filters that clean the air in your residence.
They each get rid of dust, allergens, bacteria and other airborne debris from the air that is drawn into the furnace and air conditioning system, making sure the air circulating throughout your home is clean and safe.
What Is a MERV Rating and What MERV Rating Should I Have?
Once you find your old furnace filter and figure out when it should be changed, it’s time to select 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 short 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 tinier particles.
Experts say a filter with a MERV rating between 8 and 13 offers an ideal balance between having healthy indoor air quality without needlessly restricting airflow. However, people with some health conditions could need to purchase a filters with a higher MERV rating.
How to Place 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 designed to be installed in a certain direction, indicated by an arrow printed on the side of the filter frame. The filter should be put in with this arrow pointing in the direction of 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 to the heat or cooling source. Therefore, make certain the arrow points at the furnace or air conditioning unit.
Many people struggle with which direction to face their system's air filter. To help remember, consider taking a picture 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 point. A handy time to inquire about this is during a scheduled furnace maintenance visit.
How to Replace Your Furnace Air Filter
Switching out the filter on your furnace or AC is a quick and easy process. Here is a step-by-step list of how to take out a dirty air filter and exchange it for a new one:
- Turn off your furnace: Be sure to switch off your furnace before beginning the process.
- Find 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 replacement filter to point similarly.
- Take out the old filter: Be diligent not to knock out any dust or particles.
- Document the date: Write down the date of replacement on the new filter's frame. This will make it easier to keep track of when it's time for you to change it again.
- 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 your last filter.
- Secure the filter: Make sure the new filter fits nicely and close any latches or clips that lock it in the compartment.
- Turn on your furnace: Once the replacement filter is completely secured, you can turn your furnace back on.
Can a Dirty Air Filter Cause a Furnace Not to Work?
The short answer is, yes, a dirty air filter can cause a furnace to cease 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 effectively.
