Portable Air Conditioner Buyer’s Guide

Warm weather and high humidity levels can make being indoors stuffy, hot, and unpleasant. Air conditioning is a great way to cool off. Unfortunately, many central HVAC systems can be inefficient, over-taxed, or out of date, and, therefore, unable to cool properly. Many times people turn to a traditional window box for cooling, but these units are not always an option, as some Home Owners Associations have disallowed them. Furthermore, there are many rooms and spaces that cannot support a window box unit and remain warmer than desired because of a lack of proper ventilation or poor air circulation—such as garages, sunrooms, or workshops. This is where portable air conditioners (PACs) come in. These small portable cooling systems are a highly effective way to either supplement an existing central HVAC system in one room or to cool a single room standalone. Plus, these units dehumidify the air while cooling it—so your indoor environment stays both cool and comfortably dry.

There are many models of PACs available. They come with varying BTU (British Thermal Units) ratings, which roughly indicates their cooling capabilities. However, choosing the right unit for you is more than picking the highest level BTU portable air conditioner—there are many elements to consider. The following information will help you to better understand portable ACs so you can make an educated investment in the unit that best suits your specific needs.

For easy accessibility to the topics in this article, use our topic list provided below:

• About Portable Air Conditioners
• Size and Efficiency
• BTUs of Window Units versus Portable Units
• Setup and Exhaust Hoses
• Exhaust Hose Lengths
• Single Hose versus Double Hose
• Cooling Multiple Rooms
• Eliminating Collected Water
• Electrical Outlet/Requirements
• IT Specialists
• Noise Level
• Maintenance
• Special Features

About Portable Air Conditioners
A portable air conditioner is a self-contained unit that typically sits inside the space that needs to be cooled where it provides traditional air-conditioned cool air. However, unlike traditional window-based units, a portable air conditioner does not sit in the window but is typically placed on the floor.

Portable ACs differ by brand, maximum cooling area, venting configuration, and special features (such as remote controls, oscillation mode, fan speeds, etc). Most PACs (as part of their design) dehumidify while they cool, but some units feature a specialized dehumidify-only mode so the unit can function as a stand-alone dehumidifier. There are also PACs that feature heating capabilities as well.

Size and Efficiency
Perhaps the most important thing to determine when choosing a portable air conditioner is the size needed. An air conditioner that is too small will not be able to keep up with your cooling demands.
The following list is a “rough” estimate of what to expect from BTU ratings. It is a rough estimate because many factors play a role in the efficiency of a portable air conditioner: ceiling height (cubic space), insulation type (building construction), area of the country (ambient temperature), heat load in the space (people, electronics), windows, etc.

• Calculating BTUs
  When trying to estimate how many cubic feet a portable air conditioner can efficiently cover, here is a general guideline of what to expect (assuming ceiling height is 8 ft).
  
  
  •  7,500 BTUs will cover 150 sq ft x 8 ft ceilings  = 1,200 cubic feet*
•  9,000 BTUs will cover 200 sq ft x 8 ft ceilings  = 1,600 cubic feet*
• 10,000 BTUs will cover 300 sq ft x 8 ft ceilings = 2,400 cubic feet*
• 12,000 BTUs will cover 400 sq ft x 8 ft ceilings = 3,200 cubic feet*
• 13,000 BTUs will cover 450 sq ft x 8 ft ceilings = 3,600 cubic feet*
• 14,000 BTUs will cover 500 sq ft x 8 ft ceilings = 4,000 cubic feet*

*Please note that the calculations above are simply estimates based upon a bedroom in an “average” climate with good insulation.

Additionally, remember that if you have a lot of windows, heat generating appliances, reside in a very warm, humid region such as Florida, or are cooling a poorly insulated garage, etc., you will need to increase the size (power) of the unit you purchase. Getting a sufficiently sized unit for your specific environment cannot be stressed enough—underestimating your needs when purchasing a portable AC will result in significantly less cooling performance.

BTUs of Window Units versus Portable Units
It is important to note that in comparison to traditional window box air conditioners, portable air conditioners are slightly less powerful at the same listed BTU (British Thermal Units). This slight difference in power can be attributed to several different factors, which range from manufacturers inflating their listed BTU ratings to the body of the portable air conditioner unit being inside the space being cooled (and giving off heat, which makes the unit run slightly less effectively). As such, we recommend customers be conservative and buy a slightly more powerful AC than they think that they might need.

Setup and Exhaust Hoses
All portable air conditioner units exhaust hot air as part of their cooling process. This hot air is typically directed out of the space being cooled through a hot-air discharge hose. This air hose is often vented out of a window, into a drop ceiling, or through a wall to an adjacent space. Depending on the unit chosen, window kits and drop ceiling panel/kits may be available or included.

Setup requirements will vary based upon the model. Most units come with a standard window kit, which is typically made of a hard durable plastic. However, these window kits are not always one size fits all and individual adjustments may have to be made. If you have non-standard size windows, you will want to make sure that the portable air conditioner you choose can be configured to properly exhaust out a window. If you are unsure about whether your windows are easily compatible with this window-exhaust setup, please call us at (800) 934-9194. The most common issues in setting up the exhaust hose are the following:

• Window Screens — Window screens are a common dilemma when it comes to setting up the exhaust hose for a portable air conditioner. Many people want to know, “Do I have to remove my screen from the window?” The answer to this question varies based upon your particular window and screen. However, most of our customers find that they can leave the screen in the window and that the exhaust hose of the AC does not extend out from the window.

• Casement/Crank Windows — There are no portable air conditioner units that come with a window kit that will work for a casement (crank) window. However, some customers have fashioned a solution by using Plexiglas to cover their entire window area and then cutting a small hole into the Plexiglas for the hot-air discharge hose.

• Sliding Glass Windows/Doors — Setting up your exhaust hose to work with a sliding glass window/door is possible with almost all units. However, depending on the specific unit, the window kit may not fit the full length of the door. If this is the case, it will be necessary to fashion something to ensure the rest of the gap that is not covered by the window kit is properly insulated.

Single Hose versus Double Hose
There is a bit of a debate as to whether a single hose or double hose system is more efficient. Although the research is inconclusive, it is helpful to understand how the units differ when deciding between models.

• One Hose Unit – A single hose unit works by taking in air from the room that it is in and returning most of that air back into the room as cold conditioned air. However, a small amount of that air will be used to cool the unit and be blown out of the air conditioner's exhaust hose. This results in a slight negative pressure in the room being cooled as a small amount of air is constantly being removed from the room. If this negative pressure is adjusted for by drawing unconditioned air into the room from adjacent spaces (pulling air underneath the door, from gaps around windows, etc), then the cooling efficiency is slightly affected.
  
  
• Dual Hose Unit - A dual hose unit works by taking in air from the outside through one of its hoses and using that air to cool the unit - and then that hot air is expelled through the exhaust hose. As such, it does not create negative pressure inside the room being cooled and may be more efficient in that regard. However, dual hose units use warmer unconditioned air to cool their compressors, which results in slightly less efficiency. Depending on the design, they may also use two fans internally, which results in a slightly higher energy usage.
  
  
• Hot Temperature Consideration - Another important point to consider when deciding between a single hose and a dual hose unit is the outside temperature. Specifically, if you have a dual hose set up where the intake hose is pulling air from outside when the temperature is high (say approaching 100°F), then the air being taken in to cool the unit down may actually be hotter than the unit’s compressor. The result of having very hot intake-air is that the unit may not function properly or be less efficient than if the intake-air was coming from inside the room (as the air inside would be much cooler). 
• Bottom line: The verdict is out.  There are pros and cons to dual hose units and there has not been a definitive study to confirm the benefits over single hose units. If you are uncertain which unit to purchase, some dual hose units can be modified very easily to be a single hose unit (simply detach the second hose per the owner’s manual).

Cooling Multiple Rooms
Many people are interested in cooling multiple rooms with their portable air conditioner. Whether this will work for your particular environment depends on several factors (similar to the same factors you must consider when purchasing your portable AC in the first place):

• Temperature of the room: a portable air conditioner can only lower the temperature in your room roughly 10-15 degrees
• Climate you live in: humidity level and temperature have a direct impact on the effectiveness of a portable air conditioner
• Size: an accurate estimate of the space you want to cool, including ceiling height

Like a window-box air conditioner, portable air conditioners work best at cooling their immediate area. If a space has very large openings from one room to another, then it is possible that adjacent spaces may see some beneficial effect. However, the cold air will not travel down the hall or through narrow doorways. Fans can also be used to help circulate air.

Eliminating Collected Water
When air is cooled water is removed from the air. As such, all portable air conditioners remove water from the air while they are cooling. There are many different ways that various models deal with this condensate water.

• Buckets: The simplest units have an internal container that needs to be drained regularly (as frequently as every 8 hours to as infrequently as once a month depending on your conditions). Most units have a drain plug that needs to be removed to drain the unit.
  
  
• Self-Evaporating: More sophisticated units can evaporate a great deal of moisture into their hot-air discharge, and hence there is either less or even no water to empty.
  
  
• Fully Evaporative: There are a few models of portable air conditioners that are completely evaporative, meaning you never have to dump collected water. These units are especially desirable if you need a unit that you can turn on and leave running unattended.
  
  
• Gravity Drain: All units support the option of a permanent water drain hose connection, which allows for water to continuously drain out via gravity.
  
  
• Condensate Pumps: Condensate pumps are also available to help pump collected water through a drain hose. They can move water in an upwards direction if needed. The hose can then be directed outside or to an inside drain point.

IT Specialists
Many of the portable air conditioners we sell go into computer server rooms. These units are oftentimes used for supplemental cooling or as primary cooling during the weekends when the air conditioning is generally shutoff.
Choosing the right portable air conditioner for server rooms is sometimes a challenge because most server rooms do not have easy window access or may be in an interior room. As such, customers usually direct the hot-air discharge hose into a drop ceiling space (please call to determine if this is a possible solution) or through a hole in the wall to an adjacent room.
Our most sophisticated commercial units have complete kits that allow you to easily discharge hot air into a drop ceiling while allowing the unit to remain at floor level. Less expensive residential units may also be used but must be elevated towards the ceiling to allow their hot-air discharge hoses to reach ceiling height.

Noise Level
Some people call it noise, others sound, and some background noise or white noise, but whatever it’s called it does exist—you simply cannot find a silent portable air conditioner. They can’t be totally silent because of the motorized fan and compressor system that cools and circulates the air. Even though PACs are not silent, the amount of sound they produce varies considerably. Consider the following elements when deciding what type of unit will best suit your indoor needs:

• Will the unit be in my bedroom? This is the number one area where people find the sound the most intrusive. If you are a person who does not like any noise while falling asleep, having a portable air conditioner with a timer that can be set to come on after you are deeply asleep might be the ideal solution. However, on the flip side of the sound issue, many people enjoy the “white noise” created by a portable air conditioner.
• Bottom line: Understand that a sound will come from these units and it’s just a matter of finding the level of sound you are comfortable with, or getting a unit with the special features that will help you to minimize the sound (timer, multiple fan speeds, etc).

• What sound level is the unit comparable to? Some units list the decibel rating of the system at each fan speed. You can compare these ratings to other indoor appliances, such as the level of sound you hear from a normal box fan or the hum of the refrigerator, which can give you a point of reference.
• Bottom line: Remember that sound is different to each individual, and even decibel results can sometimes be misleading as many things can affect sound level, such as position of the unit, carpeting, furniture, distance from the unit while it is running, fan speed, etc.

• Clean air filters as needed (usually once a summer)
• Make sure installation is correct for maximum efficiency
• If ice builds up on coils, defrost the unit completely before attempting to use it to cool again
• Consult a professional if you hear rattling or feel the compressor isn’t working properly (check your warranty for more specific information on parts/services covered)
• Drain your unit before storing it away

Properly maintaining your unit will ensure that it has a long life span. Portable ACs can last anywhere from 6-15 years depending on the model.

• Castors for ease of mobility
• Digital controls
• Remote control
• Multiple fan speeds
• Handles
• Dehumidify-only mode
• Heating capability
• Integrated timer

There are also a number of accessories you can purchase to customize your portable AC to further meet your needs.

Still Got Questions?
For more information on specific products and ways to improve your indoor environment, review our extensive product listings and other educational materials. Not sure what’s best for you—we can take the guess work out of decision making, contact our product experts toll free at 1 (800) 934-9194. Our goal is to make your indoor environment a healthy one.