The "size" of a spot cooler or portable air conditioner is rated in terms of British Thermal Units, commonly known as BTUs.
The British Thermal Unit is a measure of the amount of heat required to raise the temperature of one pound of water by 1 degree Fahrenheit.
There are 12,000 BTUs to 1 Ton. Don't panic.... this has nothing to do with the actual WEIGHT of the unit! A ton of refrigeration (remember... that's 12,000 BTUs) is the amount of heat required to melt a ton (2,000 pounds) of ice at 32 degrees Fahrenheit.
Sorry you asked? The main thing you need to know (so you have some idea what the AC tech is talking about) is that 1 ton of air conditioning = 12,000 BTU.
Spot coolers come in several different sizes. To figure out what size spot cooler you need there is a three step process. Think of the three "S" process.
Once you have this information, you figure out your heat load which is a fancy term for the heat you have to get rid of. This is nothing more then plugging numbers in and applying some general rules of thumb.
The Cooling Guides below will get you started. We're anxious to help you keep cool.