BTUH stands for British Thermal Unit Hours. It is a simple measurement of heat. One BTU represents the quantity of heat necessary to raise one pound of water 1 degree F. 12,000 BTU's of total capacity per ton of air conditioning (example: A four-ton air conditioning machine has a capacity of 48,000 BTU's). 8,000 BTU's of sensible cooling per ton of air conditioning (approximately).