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Confused About the Air Filter Arrow Direction?

Stephen Jabro

How to Know Which Direction the Arrow Goes on a Furnace Filter

Which way does it go in? Confusion about Air Filter Arrow Direction in a furnace

When putting in an air filter, do you know which direction to put it in?

It is not all that uncommon for a homeowner to not be sure how to put in their furnace’s air filter. Each furnace unit is different, after all. How you had installed the filter in your last heating system is probably not the same way your new system is set up. If you are new to home maintenance, it may be your first time changing an air filter and are finding it not obvious.

At Jon Wayne Heating & Air, we see the reasons why homeowners need to be on top of changing their air filters regularly. We have repaired heating systems across southern Missouri for decades, and we’ve seen the problems caused by not having a clean air filter installed in the home’s HVAC system.

According to the U.S. Department of Energy, a furnace running with a dirty or clogged air filter can cause a home’s energy consumption to increase by 5 – 15 percent!

Potential problems from not having a clean filter installed:

  • Higher energy bills
  • Foul odors
  • Bad indoor air quality
  • Home is not being heated properly
  • Furnace breaking down many years before it should


Which Direction Does the Arrow Go on a Filter?

The arrow on a furnace filterWhat do we mean when we talk about airflow direction? It’s simply the direction the air is moving through your home’s heating and cooling system.

Many people think of air filters as furnace filters, but in most systems, these air filters are for both your furnace AND air conditioning. That is why you must make sure there is a clean air filter installed in your system all year round.

One part of your furnace heats the air. A fan pushes that warm air through your HVAC system and into your ducts. That is how heated air makes its way up through your vents.

How to know what direction the airflow is going: If you already have a filter in the system, just see what direction the arrow on that filter is pointing. Put in your replacement filter with the arrow pointing in the same direction.

There are some instances when this isn’t a workable solution:

  1. There is not an air furnace filter already installed
  2. You took out the air filter before seeing which direction the arrow was pointing
  3. You doubt that the existing air filter was put in the right way

The arrow needs to point toward the unit (technically, it will be pointed to the blower motor component in your home’s system). It will also be pointing away from the return duct.  If your unit is on the ceiling, typically it should point towards the ceiling.

You can refer to your furnace manual for arrow instructions if you still have it.

You mustn’t put an air filter in the wrong way. Installing it incorrectly reduces proper air flow. That can result in inefficient heating as well as a lot of possible furnace problems down the road, most of that will be a lot more expensive than the cost to replace an air filter.


Permanent Solution to Solving Air Flow Direction Confusion

Use a marker to indicate the correct air filter arrow direction

Our best tip to avoid this problem in the future requires just a marker. Once you have identified the right direction for your air filter’s arrow, draw an arrow with a permanent market in that direction on your furnace. So even if someone forgets to check the arrow before a filter gets removed, this mark will always be there to show you the right direction.



Call Jon Wayne for Furnace Maintenance & Repair

The team at Jon Wayne Heating & Air has been servicing homes and businesses in Springfield, Mt. Vernon, and communities across southern Missouri for decades! We can repair every type of furnace and heating system so you can count on our skilled technicians to fix whatever problem you are having.

Jon Wayne Heating & Air provides professional maintenance service. We will make sure your system is running efficiently and safely. Our team is available for 24/7 emergency furnace repair. In the Springfield area, call (417) 831-9500. In the Mt Vernon area, call (417) 466-2515.

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