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 role in keeping its system operating 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 shorten its life span.
Making sure your furnace uses a clean filter that is suitable for your needs is not only about keeping your furnace operating efficiently. It’s also about providing good indoor air quality for your household.
The quality of the air your family breathes is important to the HVAC specialists at Three Rivers Heating & Cooling. We've long been dedicated to bettering indoor air quality in Portland. Here, we’ve answered common questions about HVAC filters, including that particularly 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 important to replace dirty air filters in a furnace or air conditioner periodically. Dirt-clogged filters cause the system to worker harder than it should because it takes more energy to pull air through the plugged-up filter.
Officials recommend checking your furnace filter every 30 days and replacing it if it’s dirty. You’ll know if the filter needs to be changed because it will be gray or black from dirt or dust. Those who have pets will probably 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 usually installed in the return air duct or blower compartment before the return air goes back into the furnace. This makes sure air entering 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 generally housed inside of a slot, frame or cabinet for easy access and replacement. Always refer to your furnace's owner manual for information concerning 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 AC filter are basically identical. While they might be called different things based on the current season— summer or winter—they are all filters that clean the air in your residence.
They each eliminate dust, allergens, bacteria and other airborne debris from the air that is drawn into the furnace and air conditioning system, ensuring the air flowing through your home is clean and safe.
What Is a MERV Rating and What MERV Rating Do I Need?
Once you track down 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 approach to this is by choosing an appropriate MERV rating for your needs.
MERV stands 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 bigger numbers indicating enhanced capabilities to filter smaller particles.
Experts say a filter with a MERV rating between 8 and 13 offers a good balance between having healthy indoor air quality without unnecessarily restricting airflow. However, people with specific health conditions could 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 crucial for the efficient operation of the heating or cooling system. Air filters have a certain direction, indicated by an arrow located on the side of the filter frame. The filter should be put in with this arrow pointing toward 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 toward the furnace or air conditioner.
Many people struggle with which direction to install their system's air filter. To help remember, consider snapping a quick photo 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 great time to do this is during a regular furnace maintenance visit.
How to Change a Furnace Air Filter
Replacing 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:
- 1. 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 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 similarly.
- Remove the old filter: Be careful not to knock out any dust or dirt.
- Record the date: Write down the date you changed filters 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 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 correctly and close any latches or clips that lock it in the unit.
- Turn on your furnace: Once the replacement filter is safely installed, 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 limit its lifespan. Changing your furnace or air conditioning filter is one of the easiest things you can do to keep your system working efficiently.