Can You Use a Portable Air Conditioner Without an Exhaust Hose?

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If you have just purchased a portable air conditioner, you may be surprised to find that it comes with an exhaust hose. 

With all the trouble that comes with setting up an exhaust vent, you might ask yourself: Can I run my portable AC without an exhaust hose?

To answer that question, we’ll need to explain how a portable air conditioner works, and why the exhaust hose is necessary for your AC to function.

What happens if you don’t vent a portable air conditioner

The purpose of the exhaust hose is to blow out warm air from your room. Portable air conditioners work by removing heat from the air inside of your room. 

But the heat that it removes from your room needs to be put somewhere. This is where the exhaust hose comes into play.

As your portable AC removes heat from the air inside your room, it blows this heat through the exhaust hose.

This means that if you don’t use the exhaust hose, then your portable AC will blow all the heat right back into your room.

If you want to use your portable AC as a dehumidifier the effects of this can be desirable. By removing the vent hose and setting your portable AC to dehumidify mode, you can turn your portable AC into a dehumidifier. If you use your portable AC in this manner it will dehumidify, but not cool your room.

How a portable air conditioner works

To understand why using an exhaust hose is important, you need to know how a portable air conditioner works.

A portable air conditioner works by removing heat from a space by means of a refrigeration cycle.

What is the refrigeration cycle?

The refrigeration cycle allows your air conditioner to capture heat and move it to a different place. 

The refrigeration cycle works by using a liquid-vapor refrigerant to move heat from one place to another:

  • As a liquid-vapor mixture, the refrigerant absorbs heat through an evaporator coil. As heat is absorbed in the evaporator, the refrigerant transforms into a vapor.
  • After the evaporator, the refrigerant vapor flows into a compressor. In the compressor, the refrigerant is compressed into hot vapor.
  • As a hot vapor, the refrigerant flows into a condenser. In the condenser, the refrigerant vapor loses its heat and condenses into a liquid.
  • After the condenser, the liquid refrigerant flows into an expansion valve. In the expansion valve, the liquid refrigerant loses pressure and expands into a liquid-vapor mixture.
  • Finally, the liquid-vapor mixture flows back into the evaporator coil, and the cycle repeats.
Air conditioner refrigeration cycle diagram

Using the refrigeration cycle, the air conditioner facilitates heat transfer from one area to another. The evaporator will absorb heat from inside your home, and the condenser will put that heat outside.

The first law of thermodynamics states that energy cannot be created or destroyed, it can only change forms. 

The implication here is that the heat that your air conditioner removes from your room cannot be destroyed, it can only be moved somewhere else. This is why you need to direct the exhaust vent outside.

How to vent a portable air conditioner without a window

Many people shy away from portable air conditioners because they don’t have a window to vent them out of. But there are other ways to vent your portable air conditioner, even if your room doesn’t have a window.

One way to vent your portable air conditioner is through a door. There are vent kits that are made specifically for venting a portable air conditioner out of a doorway. 

If your door is a sliding door, you won’t have much trouble venting your air conditioner. But if you have a regular door that swings on its side, then there are solutions for that too. Using a door vent kit, you can direct your exhaust hose to the outside while you leave your door cracked open.

Quick Pick: Portable AC Door Vent Kit

HOOMEE 220″ Universal Window Seal

This vent kit is made for large windows but also works for doors.

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Ventless portable air conditioners

If you absolutely need to cool your room without using a vent hose, then a ventless portable air conditioner is one option. Ventless air conditioners are also known as “swamp coolers”.

A swamp cooler works much differently than a normal air conditioner. Instead of moving heat from your indoor air to the outside, a swamp cooler works by trapping heat by converting water from a liquid into vapor. 

If you’re confused about how a swamp cooler works, the principle is like sweating. As your sweat evaporates, it carries away heat from your skin in the vapor. As water evaporates from a swamp cooler, it absorbs heat from your room’s air.

The main drawback of swamp coolers is that they can make your room excessively muggy. This is the effect of humidifying your room to cool it.

Swamp coolers also perform poorly in humid areas. If you live in a warm, tropical climate, then a swamp cooler will barely work at all.

As a rule of thumb, the dryer the air, the better a swamp cooler will perform. In fact, swamp coolers are actually a preferred method of cooling in hot, dry climates. This is because in addition to cooling the air, a swamp cooler will also add humidity to the air. 

Quick Pick: Portable AC Swamp Cooler

Briza Cool Air Cooler

This ventless portable AC will cool your space by evaporating water from a liquid into vapor. It will only work well in dry areas, though.

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