Furnace Air Filter Direction

How to Know Which Direction the Filter Arrow Goes


It is not uncommon for a homeowner to be confused about how to put in their filter. And unfortunately, there is not one simple answer. Each heating unit is different. How you put in the filter for your last furnace is likely different than how your current system is set up. However, there are some fundamentals to how nearly all filters and furnaces are built, so fortunately you are not out of luck.

If you are new to home maintenance, this may be your first time changing an air filter. Or if you are dealing with an unfamiliar system, you may be confused how this set up works. Finding out which way to put the filter in is not always obvious.

At PD Plumbing, Heating and Cooling, our technicians have repaired heating systems across the entire Wichita area for decades. We see all the problems that can happen when homeowners are not on top of changing their furnace filters regularly. According to the U.S. Department of Energy, a home heating system that is running with a dirty or clogged air filter can raise your home’s energy use by 5 – 15 percent. That’s a huge utility bill you do not want to get in the mail.


Problems Caused by Not Having a Clean Air Filter

Air Filter Arrow Direction Here are just some of the problems that can happen if you are running your system without a filter or with a very dirty one:

  • Bad smells odors
  • Poor indoor air quality
  • Home not getting heated consistently
  • High energy bills
  • A furnace needing a lot of repairs or breaking down completely many years too soon


Which Way Does the Air Filter Arrow Go?

The reason why you need to have the filter in the correct way is for proper air flow direction. Simply put, airflow direction is the direction the air is moving through your home’s heating and cooling system.

A part of your furnace first starts by heating the air. Then a fan pushes that warm air up into your ductwork and out through your vents.

Some people think of air filters as furnace filters, but in reality, these filters are typically used for both your heating and cooling. So proper filter maintenance isn’t just for the winter. You need to ensure that you have a clean air filter in your system all year round.


How to know what direction to put your filter in:

furnace Filter Direction

The easiest way to know how to put in a filter is by replacing the old one in the exact same way. If you have a filter in already, simply look to see what direction that filter’s arrow is pointing. Then put your replacement filter in with the arrow pointing in the same direction.

Unfortunately, there are sometimes when that easy solution isn’t going to work:

  1. When there is no filter in there already
  2. If you took the filter out before noting which direction the arrow was pointing
  3. Or when you have reason to believe that old filter wasn’t put in the right way

If the easy way isn’t an option, then you just need to understand the proper furnace airflow. The filter’s job is to remove particles and impurities before the air reaches the furnace to heat it. So that means the arrow will nearly always be pointing toward the furnace.

The filter works to clean the air before it enters the furnace. Otherwise your heating unit can get dirty and damaged and be prone to breakdowns. Plus that is the direction the air is flowing. Installing a furnace filter in the opposite direction will reduce proper air flow. And that can reduce your furnace’s ability to heat your home.

If you still have your furnace manual or can locate it online, you can always refer to that to determine how to install your air filter.


A “Sharpie” Solution to Solving Filter Confusion

marker your furnace filter directionYou can avoid this problem happening again with a simple marker.

Once you have determined the right direction your air filter’s arrow should be pointing, draw an arrow in that direction directly on your furnace.


Professional Furnace Maintenance & Repair

furnace repair technician wichitaPD Plumbing, Heating and Cooling has been servicing homes and businesses in and around Wichita, KS since 2006. Our experienced team of HVAC technicians has repaired every type of furnace and heating system and can be counted on to fix whatever system you have.

We provide professional maintenance service to make sure your system is running efficiently and safely. Contact us to schedule a maintenance check, ideally before the cold months start.

You can request service with our online form or by calling us at 316 871-5499.



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