Furnace Air Filter Direction: Which Way Should The Airflow Arrow Point?

Strangely enough, there is actually a wrong way to insert your furnace filter. Keep in mind that air flows from the ducts, passing through the filter and eventually into the furnace, which means the filter arrow should always be pointed facing the furnace.

It can definitely be a challenge to determine the direction of the airflow arrow points when installing your HVAC unit. Let’s take a look at why it’s important to point your filter arrow correctly and how exactly to do it.

Why Is It Important to Put Your Furnace Filter Correctly?

The direction you put your furnace filter in is incredibly important. Having your airflow arrow facing the furnace allows it to collect pollutants and allergens before they can reach the furnace’s equipment.

This means that if a furnace filter is installed backwards and incorrectly, it could prevent it from doing its job and hamper the furnace’s efficiency. Your filter will accumulate dust and debris much quicker, forcing your HVAC unit to work harder and subjecting it to unnecessary wear.

By incorrectly installing your airflow filters, you are also negatively impacting the health of everyone living in the home with you.

Where Is the Furnace Air Filter Located?

The location of furnace air filters usually varies depending on the type of furnace your house has equipped.

For instance, an upflow furnace where the air moves upwards out of your HVAC system usually has its filter in the blower compartment next to the return duct.

An HVAC unit that has the air flowing downwards out of the unit has its filter attached to the engine and found in the upper-blower compartment.

On the other hand, a horizontal furnace has a built-in sliding furnace rack that you can slide out of the unit in order to access the filter.

Meanwhile, some people living in hotter climates have an air handler that heats air using electric coils instead of a regular furnace with gas. In this case, you can usually find its built-in filter rack behind a door in the unit.

How to Properly Replace the Furnace Air Filter?

To properly replace your air filter, here are the steps you can follow:

  1. Determine the location of your filter. Usually, it can be found adjacent to the furnace and right where the furnace meets the ductwork.
  2. Locate the filter air box of your furnace. Find the ducts by standing in front of the furnace and then pull the old filter out to discard it. 
  3. Your new air filter should have an arrow on it that indicates the right airflow direction. Make sure that the arrow is pointing toward the furnace and away from the return duct. You can draw the arrow with a permanent marker on the furnace or ductwork to make it easier. You can also label the filter with the date you changed it so you can keep track.
  4. Place the new filter in with the arrow facing the furnace.

It’s not difficult to replace the filter of your HVAC unit. Just keep in mind that air flows in from the ducts, passing through the filter and then into your furnace. This means that the arrow points should always be facing your furnace.

Check out this article about the best washable electrostatic HVAC furnace filters.

How Often Should HVAC Furnace Filters Be Changed?

Most manufacturers of air filters and HVAC units usually recommend changing your HVAC furnace filter every ninety days or three months. Of course, it’s not concrete and can change depending on a number of factors such as home location, pets, age of your HVAC system and the equipment.

For people with a pet at home, it’s ideal for them to change their air filters every sixty days or two months. If you have multiple pets or have people in your home suffering from allergies and respiratory conditions, it would be better to replace your filter every twenty to forty-five days.

Homes that are rarely used and only inhabited for vacation purposes can afford to wait nine to twelve months before changing their air filters.

Overall, the basis for changing your furnace filter is how much you use your home and the severity of the dust and debris that can be found in your house.

Read also: Reasons why your room is so dusty and what can you do

Final Words

Now that you’re more aware of the proper way of installing your air filter in the furnace, you should make sure to regularly maintain it so your HVAC system doesn’t suffer from wear and can keep your home safe and comfortable for a long time.

With a lifelong fascination with HVAC mechanics and a mechanical engineering degree from Berkeley, Thomas Johnson boasts years of industry expertise. He founded AirComfortLab.com to fill the void of understandable and useful online information about complex HVAC systems. As the chief editor, Thomas strives to provide accurate and engaging content to help readers make informed HVAC decisions.

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