Ton of refrigeration
A ton of refrigeration (commonly abbreviated as RT) is a unit of power used in some countries (especially in North America) to describe the heat-extraction capacity of refrigeration and air conditioning equipment. It is defined as the heat of fusion absorbed by melting 1 short ton (0.893 long ton; 0.907 t) of pure ice at 0 °C (32 °F) in 24 hours. It is equivalent to the consumption of one ton of ice per day and originated during the transition from stored natural ice to mechanical refrigeration.
A refrigeration ton is approximately equivalent to 12,000 BTU/h or 3,517 W. Air-conditioning and refrigeration equipment capacity in the U.S. is often specified in "tons" (of refrigeration). Many manufacturers also specify capacity in BTU/h, especially when specifying the performance of smaller equipment.