Why are A/C units rated in tons?

[mikebw]

I was just wondering if anybody knew this offhand. It doesn't seem to make any sense to me, like tons of cold means something?

[kap]

[quote mikebw]I was just wondering if anybody knew this offhand. It doesn't seem to make any sense to me, like tons of cold means something?
How does the saying go again ... it's cold like a wit ... Ok. It just simply means it's arse-freezing.

[OWC Jamie]

A "ton of refrigeration" is defined as the cooling power of one short ton (2000 pounds or 907 kilograms) of ice melting in a 24-hour period.

[mikebw]

[quote OWC Jamie]A "ton of refrigeration" is defined as the cooling power of one short ton (2000 pounds or 907 kilograms) of ice melting in a 24-hour period.
I see. Not something I would guess most people have had an occasion to know, much less use in conversation. Thanks.

[JoeH]

Used to have to know that kind of thing for my class in converting between various system of engineering units 30 years ago. But the unit of a "ton" of cooling comes from the days when refrigeration units were starting to replace ice cut from lakes in winter. So the buyers wanted to know how many tons of ice the unit they were buying would replace.

[OWC Jamie]

I can look out my kitchen window at one of those 'ice ponds' and the flat field they stored the ice on .

[OWC Jamie]

Wikipedia is your friend I knew it but not exactly why.

Remember; the first A/C systems were ice block chillers. Modern Marvels (TV show) had the history of A/C on and I do recall them covering that.

Also from wiki (interesting to me since my great-grandfather worked with ammonia chilling systems in a dairy for 30 years)

In 1820, British scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate. In 1842, Florida physician John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hospital in Apalachicola, Florida.[7] He hoped eventually to use his ice-making machine to regulate the temperature of buildings. He even envisioned centralized air conditioning that could cool entire cities.[8] Though his prototype leaked and performed irregularly, Gorrie was granted a patent in 1851 for his ice-making machine. His hopes for its success vanished soon afterwards when his chief financial backer died; Gorrie did not get the money he needed to develop the machine. According to his biographer Vivian M. Sherlock, he blamed the "Ice King", Frederic Tudor, for his failure, suspecting that Tudor had launched a smear campaign against his invention. Dr. Gorrie died impoverished in 1855 and the idea of air conditioning faded away for 50 years.

[mikebw]

Yes, Mr. Wiki and I are good friends. I didn't think many people would actually know what the definition would be without looking it up. I certainly did not.

[freeradical]

Heat of fusion

6.02 Kj/mol

[macphanatic]

Trane has reintroduced a chiller system that uses ice.

Here is a youtube video:

http://www.youtube.com/watch?v=q2hdUNmdoso