Which Way Does An Air Filter Go?

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As you may well know, you must regularly switch out air filters. This is to ensure proper air cleanliness. However, did you know that it is a case of just swapping air filters over?

You also have to pay attention to the direction that you install the air filter in.

On this page, we will talk you through a few situations where you may be installing an air filter. We will tell you exactly how to identify the correct direction to install the filter. 

Which Way Does an Air Filter Go?

Most air filters will have an arrow on them. The arrow should be pointing inward towards the furnace, ceiling, wall, or whatever else is covered up by the air filter. 

If there is no arrow on the air filter, then you will need to look for the wireframe on the air filter. This wireframe should be on the outside of the air filter, i.e., it should be pointing away from the area covered by the air filter. 

In some cases, the air filter will only install in one direction. This means that you won’t have to worry too much about which way that arrow is pointing. Just slot the air filter is the only way that it fits.

Why do Air Filters have a Direction?

Air filters have a direction to ensure that the air is filtered correctly. 

When a filter is installed correctly, the air filter should filter out the largest particles in the air first. It should then filter out the smaller ones.

When the air filter is installed in the wrong direction, the big particles get trapped, but there isn’t anywhere for the smaller particles to go. The system starts to get clogged up, and airflow is reduced.

Filters installed in the wrong direction will also be structurally unsound. The purpose of the wire mesh is to hold the air filter’s structure as air rushes through. If it is the wrong way around, it doesn’t support the structure. Instead, it sort-of weakens the structure, which is never a good thing.

Does it Matter which Way an Air Filter goes in?

Yes.

If the air filter is installed in the wrong direction, it will not filter the air properly. Airflow may be stalled. In some cases, the structural integrity of the air filter may also be reduced.

Which Way Does an Air Filter go in the Ceiling?

If you are installing an air filter in the ceiling, you will want to ensure that the air filter’s arrow is pointed toward the ceiling.

If there is no arrow on the air filter, you will want the wire mesh on the outside.

Likely, the air filter will only install in one direction.

Which Way Does an Air Filter go on the Floor?

The arrow on the air filter should always be pointed toward the floor. 

If there is no arrow, then the wire mesh of the air filter should be on the outside face (i.e., the one that you can see if you look at the floor)

Which Way to Put Air Filter in Furnace?

When installing a new air filter, you need to make sure that it is installed correctly. This will allow the air to flow through it effectively.

You will need to pay attention to the arrow on the air filter. This is meant to indicate the direction that the air should be flowing through the filter.

Since you want the air flowing into the furnace, you will want the arrow pointing toward the furnace. If you install it in the opposite direction, the furnace will have to work a lot harder. This can increase energy bills, resulting in excess wear and tear on the furnace.

If there is no indicating arrow, which is exceedingly rare, then the air filter’s wire mesh will need to be on the outside. This will be the side that is facing you when you install the new air filter.

Which Way Does an Air Filter go in a Car?

If you are installing an air filter in your vehicle, then you will need to pay attention to the direction that you install it in. 

In almost all cases, car air filters will only fit in one way. This means that you won’t be able to ‘mess up’ the direction that you install it in.

If you want to be 100% sure that the car air filter is installed in the correct direction, you will need to pay attention to the air filter’s arrow. This arrow should be pointing toward the air conditioning unit on your vehicle. Essentially, you want the air flowing from the car and into the air conditioning system.

Which Way Does an Air Filter go in the Wall?

When you install an air filter in the wall, the air filter’s arrow should always be facing toward the wall. If there is no arrow, make sure that the wire mesh is on the outsidei.e., it should be pointing away from the wall.

Air Filter has No Arrow

If an air filter does not have an arrow, then double-check. In some cases, the arrow can be incredibly small.

If you are 100% sure that the air filter does not have an arrow, then the side with the wire mesh should be facing outward. 

What Happens if Air Filter is Backward?

Air will not be able to flow through the system as efficiently. 

Since there will be reduced airflow, the system that the air is running through will have to work a lot harder. This means that your energy bills will start to climb. In rare cases, it may even result in damage to the system. 

Remember, if there is reduced airflow, it will be putting a lot more strain on the components in the furnace or the air conditioner. This means that your maintenance bills are going to be a lot higher.

Which Side of Air Filter Faces Out?

The air filter side that faces out will almost always be the side with the wire mesh.

If there is no wire mesh, then the side of the air filter that faces out will be the side that allows air to flow in.

If you look at the air filter, you will see an arrow. That arrow should be pointing toward whatever you are installing the filter on. So, if it is a wall, then that arrow should be pointing toward the wall, etc.

Does the Arrow Point Up or Down on an Air Filter?

It depends on where you are installing the air filter.

If you install the air filter on a ceiling, then the arrow should always be pointed up.

If you are installing the air filter on a floor, then the arrow should always be pointing down.

If you install the air filter on a vertical surface, e.g., a wall, then the arrow should always be pointed toward the wall. 

How to Change an Air Filter the Right Way

Firstly, make sure that you have the correct replacement filter. If you are unsure, then consult the manual that came with your furnace or air conditioner.

Your first job after this is removing the old filter.

To remove the old air filter, you will need to turn the air conditioner or furnace off. 

Removing the old filter is often going to be a case of just sliding the old filter out. Most systems are pretty easy to deal with nowadays.

If you can’t just slide the old air filter out, then look for clips or screws. You may need to löosen these before you remove the old air filter. If there are screws, make sure that you save them. You may need them to install the new filter.

Once the old filter has been removed, look for an arrow on the new filter. The arrow is important as it will tell you the direction you need to mount it. The arrow should always be pointing toward the wall, floor, ceiling, etc.

It is likely that the air filter will only fit in one direction.

Slide, clip, or screw the new air filter in place. Once you know it is secure, you are safe to turn the system back on!

Summary

Installing a new air filter should be simple. All you need to do is pay attention to the arrow on an air filter. As long as this is pointed in the direction you want the air to flow in (i.e., from the outside in), then you can’t go wrong. Most air filters are probably only going to fit in one direction anyway. 

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