Which Way Does an Air Filter Go In? (Get it RIGHT!)

Nobody likes changing out the air filters. You have to reach into awkward spots, and you never know which way the filter should go. So, when asking yourself which way does an air filter go in, you have to consider a couple of factors.

Let’s take a look at some tips and tricks that can help you change your air filters without hassle!


Which Way Does an Air Filter Go In?

To correctly install the filter, you should be looking for an arrow on the side. This guide tells you the direction of airflow. You want to align the arrow against the way the air is moving.

So, if your HVAC system pushes air out of the air vents, the arrowhead should point in the opposite direction.

The second factor you should be looking at is the type of filter you’re installing. Each type of filter will have its own orientation and instructions for installation. Filters are used for a lot of things in your home. Let’s take at the types of filters so that you get the right option for your device.

How to Install an Air Filter

Now that you know what direction your filter goes in, it’s time to install the new air filter. Make sure that you get the right filter for your device. This can be done by looking up the model number on it. If you can’t find it, you can send a picture to the manufacturer to get an idea of what the model number is. This will make sure that you get the right filter.

  • Step 1: Turn off your HVAC system
  • Step 2: Open the vent with the air filter you want to replace
  • Step 3: Gently remove the old filter, making sure you don’t release any particles trapped in it
  • Step 4: Orient the new filter depending on the type and arrow direction
  • Step 5: Lock the new filter into place
  • Step 6: Close the vent and then start your HVAC back up

Types of Air Filters

Before you start taking apart your air filter, it’s a good idea to know what type of filter you’re dealing with. There are seven main types of filters used in the USA.

  1. Fiberglass Air Filters

Fiberglass air filters are one of the most common ones you’ll come across. This is because they get the job done without being too expensive. Some argue that you shouldn’t use them though.

To manufacture this filter, they spin microscopic strands of glass together around a metal grate. That’s why sometimes it’s called a spun glass filter.

A fiberglass filter is easy to identify. It’s a little less rigid than most other filters, so you should be able to bend it easily with your hands. It’s also a little see-through. So, if you hold it to the window, you should be able to see the light shining through. 

Other than the arrow, this filter has a tab on one of its sides. This tab makes it easier to remove the filter later on. You want to make sure that the tab faces the outside, so you can reach it in the future.

  1. Washable Air Filters

Washable air filters are the second most common type. They are a little pricey, but they last a much longer time.

They have metal frames and grates. The filter medium should also feel like a hard material. That means if you push against the filter medium with your fingers, you shouldn’t be able to make a dent.

When it comes to washable air filters, both sides aren’t equal. The front is a smooth surface, while the back is dented. These indentations help the filter fit into position. So, make sure that the smooth surface is facing the outside when you install it.

  1. Pleated Air Filters

Pleated air filters have a fabric medium that folds into a specific pattern. The medium can be polyester or cotton. It looks like a network of pleats laying in rows. Moreover, there’s a plastic grate going all around the filter.

These types will have a pleated side and a plain side. You want to place the filter so the pleated side is facing outwards.

  1. HEPA Filter

HEPA stands for high-efficiency particulate air. That’s a fancy way of saying the filter can remove small particles from the air like pollen and viruses.

While a HEPA filter is a type of pleated air filter, there are a few physical characteristics that make HEPA filters stand out. For one, the separators in HEPA create a checkered pattern over the pleated filter. In addition, they usually have metal housing and industrial sealing.

Installing a HEPA filter is similar to installing a pleated air filter. Make sure the pleats are always facing the outside face of the vent.

  1. Media Air Filters

Media air filters are yet another type of pleated filter. The difference is in the medium used to create the filter. In media filters, we use a paper-like material to create the pleats. So, if you gently touch the filter medium, it should feel thin and papery. 

Installing a media filter can be a little tricky, though. Both sides of the filter look identical, so all you have to go on is the little arrow. The only way to do it is to point the head toward the vent.

  1. Electrostatic Air Filters

Electrostatic air filters are mainly composed of a cotton-paper medium. This medium can create electrostatic charges to trap particles. This alone is a good identifier. If you slowly run your hands across the filter medium, you should be able to feel a slight shock.

Much like a media air filter, all you have to go on here is the arrow guide. Just remember that the pointy end should go in the opposite direction to the airflow.

Air filters can come in different shapes and styles. Make sure to get the right one for your system by looking up the model number.
  1. UV Light Air Filters

Although they come in many shapes and sizes, the UV light air filter is the easiest filter to identify. All you have to do is look for the signature purple-blue hue.

With a UV light air filter, the direction of installation should be easy to point out. There are a few screws you have to place. Plus, you want the light to be shining in on the vent, not out into your house.

Wrapping Up

Changing out air filters can be a tedious task. Although you have to do it regularly, you probably always forget what direction the filter should go.

So, which way does an air filter go in? 

The answer will slightly change based on the type of filter you’re installing. Still, when in doubt, refer to the little arrow on the side.