For what it's worth:
Tons of airconditioning/ refrigeration was first used as a sales metric.
It is short for tons of ice delivered per day.
The latent heat of melting of one ton of ice is 288,000 British Thermal Units... BTUs.
Across 24 hours that is 12,000 BTU's PER HOUR.
Hence the term 12,000 BTU's = one TON of airconditioning.
The sales metric started when machines replaced delivered ice. The pitch ran: this machine delivers the same cold as having one ton of ice delivered each day to your establishment.
High efficiency units are now mandated by US Federal Statue. (Law)
Higher effeciency units use ever less juice to crank out a 'ton of air conditioning'.
It is not uncommon to find units with a co-efficiency of performance (COOP) above 10.
That is ten watts of juice produce 100 watts of heat transfer.
Until you know what the nameplate figures are, you'd better figure on the customer buying an energy pig. They ALWAYS sell at a discount --- cheap, cheap.
Low performance refrigeration is financial folly. The extra money spent on the best unit typically returns over 50% on the expense.
Installing the most economic HVAC would keep them and us busy for years even as it saves the users a fortune.
It's that the payback for high performance is hidden from the ultimate buyer. Globally, the world has a long, long way to go. If the ultimate payer was informed... he'd never accept the low efficiency units that are normally installed.
