Portable air conditioners are gaining in popularity these days. The main advantages over window-mounted models is that you can easily move them from room to room when needed and can be used where window units are prohibited or impractical. There are two major things that you should consider when shopping for a portable air conditioner: The size of the room to be cooled and the BTU rating of the unit.

Determine Room Size

The size and configuration of the room or rooms the unit will be cooling should be calculated. The larger and more powerful the unit, the more space it can efficiently cool. However, buying a unit that is more powerful than necessary can waste money just as an under-powered unit can. Don’t approximate – calculate:
Measure the dimensions of the room and/or rooms you will be cooling. Multiply the length by the width of the room to get the square footage. A room measuring 12” x 14” will be 168 square feet in size.

Experts advise choosing a unit with the floor plan and insulation of the room or rooms in mind, as well as the placement of windows, in which case, an HVAC professional might be called in. It’s also important not to purchase a unit with more power than necessary. The temptation for some is to turn on the unit at its highest setting, then turn it down if it gets too cold. This is problematic because it can cause condensation in the room, possibly resulting in mold growth. There is also the possibility of the unit becoming frozen as well, although many units now come with an automatic cut-off switch.

BTU Rating

The BTU (British Thermal Unit) rating is a term you will hear over and over when searching for any air conditioning unit. Technically, a BTU is the amount of thermal energy (heat) needed to raise the temperature of one pound of water by one degree Fahrenheit. More simply and for the purpose of this article, it describes the overall power of an air conditioning unit. The higher the BTU rating, the more powerful the unit. A rule of thumb is to use 30-50 BTUs for every square foot of space. So, to use our previously measured room of 168 square feet, we would need a unit that had an output of between 5,000 and 7,500 BTUs. You need fewer BTUs if the room to be cooled is mostly shaded; more if the room is exposed to a lot of sunlight. People in the room will add to the unit’s effort, so add around 600 BTU per person. Add 4,000 BTU if the area to be cooled is the kitchen.

Other Considerations

Other features to consider are how the unit is vented and whether the unit is water or air-cooled. All portable air conditioners dehumidify the air, so if the unit has a reservoir, the collected water needs to be emptied regularly. Vented units sometimes expel the collected water through the exhaust. Read the packaging on each unit to find out where the collected water goes.

Another rating should play into your decision as well. The EER (Energy Efficiency Rating) is a calculation of the number of BTUs per hour the unit puts out per each watt of power it uses. This is listed on the unit’s Energy Guide Label, which is a voluntary declaration by companies who participate in the EnergyStar® label program.

Buying Your Portable Air Conditioner

Now that we have our dimensions and requirements, it’s time to go shopping. Portable air conditioning units come in a variety of shapes, sizes and BTU ratings. Most units range in BTU output from 5,000 to 14,000 BTUs. Prices also range widely, from $250 to well over $600 and more, depending on the power, features and extras.

A note: Just because the unit is ‘portable’ does not mean that it is lightweight. Many of the floor units range in weight from 50 to 90 pounds. Choose a floor unit with casters or wheels, so you don’t have to lug it from room to room.

The convenience factor should be considered as well, as this will influence the price. Do you want your portable air conditioner to have electronic controls with a remote? If you don’t mind emptying a water reservoir regularly, you can save a little money over a portable air conditioner that expels the water with the exhaust.

Extras to consider for your portable air conditioner include ventilation kits, extra filters and drain tanks. Add these items to the overall cost when purchasing. Filters will need to be replaced regularly. Consider the cost of maintaining your portable air conditioner, as well.

If you do your homework before making the purchase, you will save yourself a lot of headache and get a portable air conditioner that will serve your needs for years to come.