Which Way Does An Air Filter Go In The Ceiling?

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Well, it’s time to change the air filter again. But because it’s only done a few times a year, it’s easy to forget which way it goes in the ceiling! We researched this to make sure you have the best information about this.

The air filter should always face the same direction as the airflow, so point the arrow -located on the filter’s edge- toward the ceiling. If there is no arrow, the side with the wire should face the ceiling.

Sometimes it’s not intuitive to know which way the air filter goes in the ceiling. But we’ve extensively explored the question -and the answers- and we have the correct information for you here. Continue reading to learn the details about installing your ceiling air filter!

Person removing an old dirty air filter from a ceiling intake vent, Which Way Does An Air Filter Go In The Ceiling?

Air Filter Savvy

First, we’re lucky that most air filter manufacturers have made changing air filters simple. Almost any home or office air filter is standard. This means that they follow specific fabrication guidelines which are the same.

So let’s take a look at the parts of an air filter.

Air Filter Parts

The Filter Frame - Usually made from paperboard for home and office AC units.

The Filter Material - Depending on your *MERV rating, the air filter is made from one or more layers of synthetic and natural materials. They are usually pleated to increase the filtering surface.

  • *MERV - Minimum Efficiency Reporting Value - this measures how well a filter removes different airborne particles.

The Filter Support - Many, if not most filters, will include a fine, wire backing or a criss-cross frame of the paperboard structure to keep them rigid. It helps to extend the life of the filter.

Air conditioner filter

The photo above shows a pleated air filter in a paperboard frame with wire backing support. This side should face the AC unit.

Now let’s see how to install the filter.

Air Filter Installation

This section will explain how to safely and correctly install the air filter. Read through the instructions before starting. No one wants to be hurt during routine home maintenance.

How To Open The Vent Cover

The vent cover is where air enters the system to be cooled. There are two/three tabs on one side of the vent cover, which are attached to hinged clips and keep the vent cover closed.

Man opening ceiling air vent to replace dirty HVAC air filter

Above, the installer is sliding open the tabs on one side of the vent.

The vent cover is attached by swinging hinges on the opposite side of these clips. These hinges can detach when in use, so be cautious.

Once you open the clips, the vent cover will swing down. Be careful, as the vent cover is heavy and can hit you in the face or head as it falls open.

White square ceiling furnace air vent grate open

The vent is open, and no filter is installed in this photo.

How To Install The Filter

  • Turn off the AC unit.
  • Position yourself below the filter with your face and head away from the vent as it swings open.
  • Slide the hinged tabs open and carefully open the cover.
  • Remove the old air filter by the edge - do this carefully. It can also fall out.
  • Turn the AC unit back on; it will help keep the filter in place while you close the frame.
  • With the arrow and metal backing facing up, place the new air filter in the frame. Do not force it.
  • Close the vent cover and slide the hinged tabs back into place.

Man replacing dirty HVAC air filter in ceiling vent

In the above photo, the air filter is being safely and correctly installed.

You’ve just completed a successful installation of your AC ceiling filter!

If  you still feel unsure, watch this helpful video:

Does The Arrow Point Up Or Down On An Air Filter?

This can be a tricky question because the arrow represents the direction in which air should flow before it enters your AC unit.

So, if your filter is located on an air intake vent on a wall, ceiling, or floor, the arrow should point at the wall, ceiling, or floor accordingly.

Texture of air filter

The arrow should always point in the same direction as airflow towards the AC unit.

If your air filter is located on the AC unit, such as in an attic or basement, the air filter usually points at the unit. Remember, you want to filter the air before it enters the AC unit to be cooled.

In this case, to determine which direction the arrow should face, look at your AC unit.

  • Note where the filter is located
  • Determine which way the air is entering.
  • ensure the arrow points in the direction of airflow into the unit.

HVAC service technician changing dirty indoor air filter in residential heating and air conditioning system

This air filter is being installed correctly. The unit is on the right, so the arrow should point to the right. The wire backing is also visible on the downstream side of the system.

Which Way is Airflow For Filter In Ceiling?

If you’re unsure which way your air is flowing, you can find out easily! Take a piece of paper, and hold it in front of the vent while the AC is running. The paper will be drawn to the vent and usually stick there.

You can also put your hand in front of the vent and feel the air either drawing or blowing away from the vent.

Whichever way air is flowing, that is the direction the arrow should face when installing an air filter. Another way to think of it is that the air should always be filtered before entering the AC unit.

Which Way Does The Air Filter Face?

Thank goodness that almost every air filter these days is imprinted with a little arrow on the edge! This will tell you which way the air filter should face.

The arrow always points in the airflow direction that goes toward your AC unit.

What if there is no arrow?

This can sometimes happen. Not every manufacturer is perfect. But don’t worry if there is no arrow; there are other ways to determine which way the air filter should face.

Remember the fine wire backing mentioned above in ‘air filter parts’? This is almost always present in quality home and office AC filters.

This metal side should face toward your AC unit. When you install the filter in a floor, ceiling, or wall air intake vent, the metal side should face away from you.

There is some conflicting online information about which way the metal should face, but we have researched this extensively, and the information here is correct. The exception is that a manufacturer may have added negative-ion attracting metal wire to a filter, which may require alternate installation. If you still have questions, contact the filter manufacturer or follow the package directions.

What if there is no metal?

If the fine metal backing is missing, you can still determine the correct direction the filter should face. Carefully examine both sides of the filter, and use a magnifier if needed. One side should be rougher or look less shiny than the other. The rougher side is the side that should face you.

This is because air is filtered with fiber that becomes smaller and smaller. Large particles are trapped in the first layers, and smaller particles are trapped in the following layers.

3 layer air filteration and virus protection

Air filters remove smaller and smaller particles as the air moves through the layers.

Still puzzled?

If you’ve looked carefully at your air filter and still can’t figure out which way to install it, contact an HVAC specialist in your area. Most of them will be happy to help you over the phone without charge. If you don’t get help from the first one you call, call the next one on the list!

What Happens If An Air Filter Is Installed Backward?

There are two main problems to worry about if the air filter is installed backward.

  1. Facing backward, it will not filter your air. This means that particles such as allergens, dust, and microbes will remain in the air. Studies show that indoor air pollution is a serious and deadly health threat.
  2. The AC unit will work harder to draw air. This can lead to high utility bills and even damage your AC unit, leading to costly repairs or replacement.

So, be sure to install your air filter in the correct direction.

In Conclusion…

Installing an air filter in your ceiling doesn’t take a professional; you can easily do it yourself! Just remember the direction of airflow should match the arrow. We’ve also included lots of other trouble-shooting and good advice above for trickier situations. Now, sit back, relax, and enjoy your ‘cool’ new accomplishment!

To learn more about your AC system, take a look at the following posts,

How Often To Change AC Filter In A Home With Pets

How To Tell Which Way Air Flows In AC Unit

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