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 critical function in keeping its system running safely, efficiently and for a long time.
An overused furnace filter loses its effectiveness, permitting potentially harmful particles to flow through your home. It also restricts 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 only about keeping your furnace working efficiently. It’s also about delivering excellent indoor air quality for your residence.
The quality of the air your family breathes is important to the heating and cooling professionals at Morgner Inc. Air Conditioning & Heating. We've long focused on improving indoor air quality in Saint Louis. 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?
How Often to Replace the Air Filter in a Furnace
Experts stress it's critical 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 extra effort to pull air through the plugged-up filter.
Officials suggest inspecting your furnace filter monthly 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. People who have dogs and cats will very likely have to replace their furnace air filter more often, because a quality 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 commonly installed in the return air duct or blower compartment before the return air gets to the furnace. This is so 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 positioned on the right, left, bottom or in some cases, within the furnace. It's generally housed in a slot, frame or cabinet for convenient access and replacement. Always refer to your furnace's owner manual for important information regarding filter location of the furnace in your home.
Is a Furnace Filter the Same as an Air Filter?
The easy answer is, yes. In HVAC, a furnace filter and an air filter or AC filter are essentially 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 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 certain the air circulating throughout your home is clean and safe.
What Is a MERV Rating and What MERV Rating Do I Need?
Once you locate your old furnace filter and determine 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 selecting an appropriate MERV rating for your needs.
MERV is short for Minimum Efficiency Reporting Values. The MERV rating calculates the effectiveness of air filters at trapping airborne contaminants. The rating scale ranges from 1 to 20, with higher numbers indicating the power to filter smaller particles.
Experts say a filter with a MERV rating between 8 and 13 offers an appropriate balance between having adequate indoor air quality without unnecessarily restricting airflow. However, people with certain health conditions may need to use a filter with a higher MERV rating.
Which Way to Put the Air Filter in a Furnace or Air Conditioner
Putting an air filter in a furnace or air conditioner the proper way is important for the efficient operation of the heating or cooling system. Air filters have a particular 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 toward the furnace or air conditioner, which is the direction of the airflow. If you're unsure about the airflow direction, remember that air always moves from the return duct and then to the heat or cooling source. Therefore, make certain the arrow points at the furnace or AC.
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 be installed. A handy time to do this is during a regular furnace maintenance appointment.
How to Change a Furnace Air Filter
Replacing the filter on your furnace or air conditioning system is an easy process. Here is a step-by-step list of how to take out a dirty air filter and replace it with a new one:
- 1. Turn off your furnace: Make a point to shut off your furnace before starting up the process.
- Locate the furnace filter: Typically, the filter is positioned inside the furnace or in the air return vent. Make a mental note or write down which direction the arrow points on the filter, because you’ll want the arrow on the clean filter to point the same way.
- Slide out the old filter: Be diligent not to knock out any dust or dirt.
- 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 the next change.
- Insert new filter: Put in the new filter with the arrow pointing in the direction of the furnace, which is the direction of airflow and should be the same direction the arrow pointed on the old filter you are replacing.
- 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 clean filter is properly installed, 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 cease working or limit its lifespan. Changing your furnace or air conditioner filter is one of the simplest things you can do to keep your system working correctly.