Ton of refrigeration
| Value | 3,516.8528420667 W |
| Status | Exact by definition — no uncertainty |
| Source | ASHRAE; NIST SP 811 (exact by definition) |
| Categories | ThermodynamicEngineering & Trade |
| nanowatt | 3,516,852,800,000 nW |
| erg per second | 35,168,528,000 erg/s |
| microwatt | 3,516,852,800 μW |
| milliwatt | 3,516,852.8 mW |
| foot pound-force per minute | 155,633.85 ft·lbf/min |
| BTU per hour | 12,000 BTU/h |
| watt | 3,516.8528 W |
| kilocalorie per hour | 3,023.9491 kcal/h |
| foot pound-force per second | 2,593.8975 ft·lbf/s |
| thousand BTU per hour | 12 MBH |
| metric horsepower | 4.7815891 PS |
| horsepower (mechanical) | 4.7161773 hp |
| electrical horsepower | 4.7142799 hp (elec) |
| kilowatt | 3.5168528 kW |
| ton of refrigeration | 1 ton |
| boiler horsepower | 0.35851499 bhp |
| million BTU per hour | 0.012 MMBTU/h |
| megawatt | 0.0035168528 MW |
| gigawatt | 0.0000035168528 GW |
| terawatt | 3.5168528e-09 TW |
| solar luminosity | 9.1871809e-24 Lsun |
Learning zone
The ton of refrigeration is a survivor from the ice trade. Before mechanical refrigeration, cooling was bought as blocks of ice, so the natural way to rate a new machine was by how much ice it replaced: melting a short ton — 2000 lb — of ice over 24 hours requires 2000 × 143.4 BTU spread over a day, which rounds to the defined 12 000 BTU/h, or 3516.85 W.
It is exact by definition, since the international-table BTU is exact. The unit refuses to die because chiller efficiency is quoted against it: kW per ton, where 0.5 kW/ton is excellent and 1.0 kW/ton is mediocre, and the coefficient of performance is 3.517 divided by kW/ton. A note for anyone reading European datasheets: a ton is a US short ton here, and a "ton" of air conditioning has nothing to do with the weight of the equipment.