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Do Portable Air Conditioners Need to Be Drained?

If you’ve recently purchased a portable air conditioner or you’re considering buying one, you might have concerns about drainage. You may be aware that all air conditioners produce condensation and that water has to go somewhere. 

Some portable air conditioners need to be drained. Newer ones are self-evaporative, venting condensation through the exhaust hose that vents hot air. Others have a drain plug, which may attach to a hose for draining or a pan or reservoir that must be periodically emptied. 

Always try to consult your user’s manual for the most accurate information about your unit. But if you don’t have your manual, or if you’re looking for more answers about portable air conditioners before deciding to buy, read on.

How Often Do You Need to Empty Your Drain Reservoir?

If you’ve determined that your unit has a drain tank, pan, or reservoir that must be emptied, you might be wondering how often you need to empty the tank. Again, it depends. The rate at which water can collect in the reservoir can vary quite a bit, depending on how humid the air is, how much the unit is used, the size of the tank, and other weather conditions.

Some units can fill up in a matter of hours, whereas other units may take a month to reach capacity.

Almost all portable air conditioners that contain reservoirs have a safety feature that will turn off the unit if the reservoir is full. This prevents spilling and leaking of water from the unit, and generally, you must empty the reservoir before the unit turns on again. Some units will also have alarms or notifications to alert you to the status of the reservoir.

Portable air conditioner

What Happens if You Don’t Drain Your Air Conditioner?

If your air conditioner has a drainage reservoir that becomes too full, it should automatically shut off to prevent overflowing of the unit, and you must drain the reservoir before continuing to use the unit. But what if the reservoir isn’t full, but contains standing water?

Most of the time that your unit is in regular use, this shouldn’t be an issue as long as you’re draining your unit properly. But what if you stop using your unit for a while?

If you don’t plan to use your unit regularly, any standing water in the reservoir should be emptied to prevent the growth of mold and bacteria. Air conditioner reservoirs can become breeding grounds for these microorganisms, causing allergies and other health issues.

How Long Can I Leave My Portable Air Conditioner Running?

Although you could potentially leave your portable air conditioner running all the time, there are a few reasons you might not want to do this. Are you using the room being cooled all day and all night?

If not, you’re likely wasting energy and costing yourself unnecessary energy bills. It makes more sense to run the unit as needed; some models even have timers or allow you to create a schedule. 

Do Portable Air Conditioners Need a Window?

All air conditioners cool the air in exchange for producing hot air that must be vented somewhere, ideally outside via a window. However, some units are capable of using doors, walls, or air ducts to vent the hot air if properly installed.  

Your unit should come with a plexiglass window kit that attaches to the window where the exhaust port goes. These kits allow you to secure your window and allow for natural light at the same time. 

What Size Air Conditioner Will Cool My Room?

Air conditioners measure their cooling power in BTUs. Smaller rooms, under 200 square feet or so, would require around 8,000 BTUs to keep it cool. A larger room, up to 600 feet, could need as much as 14,000 BTUs. An online calculator can help you determine how many BTUs you need for your space.

Portable air conditioner

What Are the Benefits of Portable Air Conditioners?

You may be deciding between portable air conditioners and other types of air conditioners such as window air conditioners or even central air. Here are a few advantages of portable air conditioners:

  • They’re portable. As the name suggests, you could move these units from room to room as needed.
  • They don’t require the use of a window. Window air conditioners aren’t the most attractive things, and sometimes you just don’t want to lose the use of the window. Portable air conditioners take up much less window space.
  • They don’t require tools or installation. Portable air conditioners don’t require much setup beyond the window kit that should come with the unit to set up the exhaust system. 
  • They’re good for spot cooling. You may be considering central air conditioning, but consider whether or not you need cooling in all areas of the home. You could cool your bedroom at night for a fraction of the cost of central air for the entire house.
  • They double as dehumidifiers. Air conditioners extract moisture from the air, so if you live in a humid climate, the added benefit of drier air can make it much more comfortable.

What’s the Difference Between an Air Conditioner and an Air Cooler?

Both air conditioners and air coolers, sometimes called swamp coolers, are capable of cooling the air. However, they do it in very different ways. Air conditioners use a chemical refrigerant flowing through coils to cool the air on the inside and vent heat to the outside.

They also absorb moisture from the air that condenses, which provides the added benefit of dehumidifying the room, which can contribute to how cool the room feels and overall comfort.

Portable air conditioner

In contrast, swamp coolers use only water and a fan to cool the air. They work on the principle of evaporative cooling, in which the air is cooled by the evaporation of water. Unfortunately, they actually add moisture to the air, which may not be ideal in humid climates.

Evaporative coolers have the advantage of not requiring a venting system, and thus can be used indoors or outdoors and don’t require a window for exhaust or drainage. They tend to also be better at cooling outdoor spaces.

Are Portable Air Conditioners Energy Efficient?

Compared to other air conditioners and other appliances, no. Portable air conditioners generally receive lower energy efficiency scores than other types of air conditioners. However, if you don’t need to cool the entire house, using a portable in one area could be a cheaper and more energy-efficient alternative to central air.

Can a Portable Air Conditioner Cool Multiple Rooms?

It’s possible, but this can depend on a lot of things. First of all, the unit has to have enough power (enough BTUs) to cool the total square footage of the space. But in addition, the shape of the room can make a difference. Due to the way air circulates, a larger, more open space will be easier to cool than narrower hallways and rooms with lots of walls. 

One way to make a portable air conditioner cool a space better is to use one or more fans that can redirect the cool air, aiding in air circulation.


Hopefully, this has helped answer your questions about how portable air conditioners work and the maintenance required, as well as addressing other questions you might have about owning a portable air conditioner.


  • Chris Hewitt

    Chris is a Texas-based freelance writer who loves the outdoors and working in his garage. When he's not enjoying the Texas sun, he can be found tinkering with all sorts of things in his workshop.

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