Does HVAC Filter Direction Matter?

Thanks to the highly efficient modern HVAC air filters out there, it’s now easier than ever to have clean air inside our homes. These filters need to be changed regularly to remain efficient since dust and other air particles accumulate on them and reduce the airflow. But you may wonder whether the direction of the air filter matters.

HVAC filter direction matters because air flows through it in one direction. While its two sides look the same, one is more porous to allow air to get inside. Otherwise, air can’t pass, and the unit itself must work harder and longer, leading to higher energy consumption and efficiency loss. 

If you’re curious about HVAC air filters and want to learn more about them, keep reading. We’ll tell you how to change your air filter properly and determine its correct direction. We’ll also go through the reasons why its direction matters. 

How To Install an HVAC Air Filter?

To always breathe fresh and clean air, you’ll need to change your home HVAC system regularly. Air filters may become clogged by dust, mold, or pet dander, and as a result, air can’t pass easily through them. You may also need to change your air filter for other reasons like physical damage or aging.

Whatever the reason, installing the air filter takes no longer than 10 to 15 minutes, but it can be tricky. Since this process can vary by the system, it’s better to first read the instructions of your specific unit

The first step in installing an HVAC air filter is to turn off your unit. If you don’t know how to do it, simply turn off the circuit breaker attached to the HVAC system. 

Then disengage the latch of the cover grille. You may find out that the grille itself is dirty, so take a microfiber cloth and clean it thoroughly. Alternatively, you can vacuum it with a brush attachment.

Now remove the old filter and replace it with a new air filter. Make sure to place it in the correct direction. Air filters come with colors and arrows that indicate how they should be oriented

Finally, put the clean cover grille back in its place and close the latch. Now you can turn on your unit and enjoy the fresh air. 

Remember that the above steps specifically apply to air return ducts, and they can slightly differ for window AC units or air handler cabinets. If you followed these steps and found out it doesn’t work properly – doesn’t turn back on, its fan rotates slowly, or makes a weird or loud noise – it’s better to call a technician and don’t repair it yourself

Here’s a valuable YouTube video that teaches you how to replace your HVAC air filter properly:

Read: Does HVAC Filter Wildfire Smoke?

Which Way Should the HVAC Filter Face?

As mentioned, air filters should be oriented in the right way to work properly and efficiently. Both sides of the air filter look the same, but it doesn’t mean that you can use them interchangeably. But which way the HVAC filter should face?

All air filters have some arrows printed on their sides that make it clear which way they should be installed. These arrows show the direction in which air flows through your HVAC system. This direction is from the supply ducts towards the blower. 

Here’s a rule of thumb: the air filter arrows should always face your unit and away from the return air duct bringing the air that’ll be cooled or heated. So, they should face the ceiling if your filter is placed on the ceiling; and they should face the wall if it’s somewhere on the wall.

If you can’t see an arrow on the air filter, which is almost impossible since nearly all of them come with arrows, keep in mind that the side with wireframe should face outward, and the side without it should face inside and toward the unit

One tip is that once you find out the direction of airflow, draw an arrow on the air filter with a permanent marker so next time you change it, you can match up the arrows on air filters.  

Alternatively, you can note the direction of arrows on the old filter before changing it and ensure the new one will also face that same direction. The new filter will be the same as the old one, so you won’t have trouble comparing the two.

It’s pretty easy to change the HVAC air filter and place it in the right direction. However, if you couldn’t find the right direction or were uncertain about it, get help from a technician

Read: How Often You Should Change The Furnace Filter

What Happens if the Air Filter Is the Wrong Way?

Not many people may know that orienting the HVAC air filter in the right way really matters. While inserting the air filter in the wrong direction may not damage your system, it’ll lower the unit’s efficiency and cost you extra money. 

HVAC units are designed to let air flow in one direction. They pull in the cold air from home and blow it back after warming it through the heat exchanger

The air inside the home carries dust or fibers; the air filter’s task is to ensure that no dust and large/small particles pass through it and accumulate on blowers or motors inside the unit. Some filters can even remove small particles like allergens and provide very healthy air for your living space. 

If you install the air filter in the wrong way, the furnace will have to work much harder to do its job correctly. The central air-conditioning units also are no different

While the two sides of air filters may look the same, one side is always more porous than the other. If you put it the wrong way, the HVAC system has to pull in air through the less porous side of the air filter, which is obviously harder and puts more pressure on it. 

As a result, the unit loses its efficiency because it must work harder for longer, leading to increased heat in the system. Besides, working hard for a longer time means consuming more energy. So, you’ll notice a surge in your utility bill. 

To top it off, the air quality of your living space will also decrease. When you place the air filter in the wrong direction, it can’t capture dust and air particles, and they’ll remain floating in the air.

Read: Furnace Filter Airflow – What You Need To Know?

Some Considerations When Buying an HVAC Filter

The HVAC air filters come in different sizes; they can be 12 to 24 inches (30.48 to 60.96 cm) wide and 12 to 36 inches (30.48 to 91.44 cm long. So, before anything, make sure you’ve got the correct size filter for your system

Besides, air filters vary in quality too. All air filters have specific ratings regarding their performance, indicating how well they can remove the large and small particles in the air. The best ones have a performance rating of 8 to 10. Such air filters can remove small and large particles, smoke, smog, allergens, and odors

What’s more, materials used in the filter, the number of its gaskets, and how well it fits in your system are some other considerations when you’re purchasing an air filter. After all, an efficient filter can save you some money in the long term and ensure you’re breathing in quality air. 

Read: Cheap Vs. Expensive Furnace Filters

Final Words

HVAC air filters can ensure you’re breathing clean air inside your living space. However, they have to be changed regularly because air filters get clogged over time and lose efficiency. When changing them, the critical point is always to place them in the right direction; otherwise, they can’t efficiently clean the air, and your HVAC system will have to work harder and for longer, resulting in higher utility bills