BTU/h
Also known as: British thermal unit per hour
Short definitionThe heat rate unit of American and British catalogues. 3,412 BTU/h is about 1 kW, and 12,000 BTU/h is 1 ton of refrigeration.
A BTU is the heat that raises the temperature of 1 lb of water by 1 °F; BTU/h is its hourly flow. The "18,000 BTU" quoted for air conditioners is really a BTU/h capacity and comes to about 5.3 kW. Divide by 3,412 to get kW, or by 3.97 to get kcal/h.
In cold room work this unit mostly appears on data sheets of imported compressors and evaporators. Converting the unit alone is not enough. American catalogues rate capacity at their own conditions, for example 95 °F outdoor air and 45 °F evaporating temperature. Before comparing with a European catalogue value, the conditions must be matched as well; otherwise the same unit shows different capacities in two documents.