What Happens When Indoor Air Conditioners Are Kept On The Floor

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Depending on the type of AC unit used in your home, there may be situations where the indoor AC unit is kept on the floor. This is normally more typical of freestanding AC units rather than split AC installations. Are there any problems associated with keeping your indoor AC unit on the floor?

Air conditioners on the floor will not be efficient. The physics laws resulting in hot air rising and cold air sinking works against the AC efficiency. This causes the unit to work harder for longer, and additional dust at lower levels can clog the filters, requiring more frequent maintenance.

All our homes are different, including our available space and cooling requirements. This may present different challenges for different people when it comes to locating their indoor AC unit. Locating an AC unit on the floor may be a logical or practical position for you, but it may pose some issues for your AC units and their effectiveness.

Thermodynamics Is A Problem For An AC On The Floor

Unboxing of new portable air conditioner unit
Unboxing of new portable air conditioner unit

The biggest problem for an AC unit on the floor is presented by the laws of thermodynamics related to air at different temperatures.

The intent and purpose of an AC unit is to cool the room down to a comfortable level for the occupants. AC units work on a heat exchange principle, where warm air is drawn into the unit, and heat is extracted from the air by the refrigerant in the AC.

This lowers the air temperature, and the now cooler air is blown out of the unit into the room by the internal fans in the AC. This is where the thermo-dynamics of the air in the room comes into play.

Most people are aware that the natural tendency of hot air is that it will rise since it is less dense thus lighter than the surrounding air. This means that warmer air will rise towards the ceiling in the room.

In contrast, cold air will sink to the lower areas of the room since it is denser and thus heavier than warm air. So how does this relate to the position of your AC in the room?

If the aircon is at floor level, it will pump out cold air, which will promptly sink to the lower levels in the room. Consequently, the air at leg and feet level will get cooler quicker, with the air temperature at head and torso level will take longer to cool.

The AC unit also needs to draw in warm air to extract its heat. However, if the AC is positioned in the cool air at the lower level in the room, once the lower air has cooled to the level of the AC air intake, the AC unit will only be taking in the cool air!

In a standard AC installation, the AC unit is mounted high on the wall, where it pumps the cold air out into the hot air at the top of the room:

Someone installing an AC wall unit
Someone installing an AC wall unit

The cold air cools the air below as it sinks down. The hot air rising to the ceiling of the room gets drawn into the unit’s air intake at the top of the room.

This results in greater efficiency of cooling the air in the room, making this the ideal placement of an AC unit. Placing the unit on the floor reduces the cooling efficiency in the room due to the thermo-dynamic action.

Floor AC Units Work Harder For Longer

Due to the inherent inefficiency of placing the AC unit at floor level, the AC will need to work harder for longer to sufficiently cool the volume of air in the room.

The additional running time has implications for all the unit’s working parts and can result in premature failure of parts of the unit.

The compressor would be the part that works the hardest during this time, and a failure of the compressor is an expensive repair to make on an AC unit.

Clogged Air Filters On Floor Level AC Units

Dirty air filter
Dirty air filter

Dust is a constant problem for AC units, and most AC units have a filter system to remove the dust from the air drawn into the air intake. This helps the unit to cool the air more effectively and improves the air quality for the people in the room.

Dust particles are small, but they are heavier than air, which results in the particles settling in the lower areas of the room. The problem for AC units kept on the floor is that their air intake is situated at a level where the dust is at a higher concentration.

The higher dust load in the air will pass through the AC unit’s air filters which will become clogged much more rapidly than an AC unit installed at a higher level.

This will increase the frequency with which the AC filters will need cleaning or replacement. Consequently, positioning an AC unit at floor level can increase the maintenance costs for the unit.

Obstacles In The Room Can Block Floor AC Air Flow

A portable AC unit in the corner of a room
A portable AC unit in the corner of a room

An air conditioner situated on the floor will have many obstacles in its way as it tries to blow out the cold air it produce.

Tales, chairs, bookshelves, and any other form of obstacle in the direct air path of the unit can prevent the AC from effectively cooling the entire room.

The obstacles in the way of the airflow will cause pockets of hot and cold air in the room, and you would need to be positioned close to the AC unit to get any benefit from the cooler air.

AC units installed above these obstacles have the advantage of unimpeded airflow for the air being pumped out of the unit. This allows for a greater distribution of the cold air, cooling the entire room rather than only cooling portions of the room.

What Can You Do To Improve Efficiency Of An AC On The Floor?

A contractor repairing an AC unit
A contractor repairing an AC unit

The main challenges of an AC unit on the floor are the airflow obstruction and the inability of the AC to cool the upper part of the air column in the room.

What can you do to improve these aspects of an AC on the floor? If you want to install a freestanding AC, new models on the market have changed the typical design that can help with both issues of an AC at floor level.

The traditional configuration of an AC on the floor is to draw air in at the back of the unit and pump cooled air out the front of the unit. Newer models are available that draw air in from behind the unit but pump the cold air out vertically from the top of the unit.

This is a much better design configuration since the cold air is pumped up, which allows it to disperse above obstacles and cool a larger portion of the column of air in the room as it sinks.

If you currently have a freestanding air conditioner of the older configuration, you need to find some way of elevating the position of the unit.

If you have stairs, you could try placing the unit on the landing at the top of the stairs if you have a window nearby for the exhaust. You can also try elevating the unit on boxes in the room so the air output is not impeded and the cold air comes out at a higher elevation.

If your aircon is a split AC unit, your options are generally limited. The refrigerant pipes connecting the indoor AC to the outdoor compressor unit are generally not long or flexible. This will limit any re-positioning that can be done with these units.


Split air conditioner units are installed with the indoor unit at a raised position on a wall in the room. This is to maximize the distribution of the cooled air throughout the space and cool a larger area of the room more efficiently.

AC units positioned at floor level will not have the same efficiency and will take longer to cool the same space than a wall-mounted AC unit. While an AC unit on the floor is not ideal, it is certainly better than having no air conditioner at all!

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About Charlie D Paige

Charlie is a massive DIY fan, with dozens of DIY projects under his belt - ranging from tiling to electrics, and concrete pads to walls. Charlie loves tinkering, seeing how things works, the outdoors and playing with power tools... so is it any wonder that he's completed so many DIY jobs over the years?

Charlie loves spreading his hard-won DIY experience with the world via this blog.