But, the conversation wove around to the unit of measurement that measures the cooling capacity of an air conditioning unit, and why do they call it a tom? Just a little research and we find that it's an archaic term that is based on the amount of energy needed to melt a ton of ice.
A ton is the cooling capacity of an air conditioning system. One ton is equal to the amount of heat required (288,000 Btu) to melt one ton of ice in a 24-hour period. A one-ton air conditioner is rated at 12,000 Btu per hour (288,000/24). A two-ton unit would be rated at 24,000 Btu per hour. Typical residential central heating systems provide up to 5-tons of cooling. Commercial systems can range anywhere from small, three-ton rooftop units, to 1,500-ton chiller systems. Why a ton of ice? The term is leftover from the days before mechanical cooling when ice was an essential part of refrigeration.So, if a ton is equal to 12,000 BTU/hr, then I have 4.5 tons of cooling hanging in the wall of my shop. (Three 18K units)
So, now I know what a ton of AC capacity is: Basically, 12,000 BTU.