What exactly is an AC ton?

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I tried looking it up on the web, but couldn't find anything that describes exactly what it means.
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12,000 BTU/hr of cooling capacity.

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And this is apparently how the term was coined:
"Tonnage The unit of measure used in air conditioning to describe the cooling capacity of a system. One ton of cooling is based on the amount of heat needed to melt one ton (2000 lbs.) of ice in a 24 hour period. One ton of cooling is equal to 12,000 Btu/hr."
from: http://www.liebert.com/support/glossary/air_gloss.asp
Smarty

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Thank you all.
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Ton is a measurement term, 2000 lbs! :-)
With air conditioning it is equivalent to 12,000 Btu/hr.
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http://www.apcmedia.com/salestools/TEVS-5TXPED_R1_EN.pdf a conversion table for A/c tons is at the end of the article
Excerpt: Ton (Cooling) A measurement of heat energy commonly used historically to measure heat loads in North America. A ton is equal to 12,000 BTUs and is the amount of heat energy required to melt 2000 pounds (907kg) of ice in one hour. This is an archaic term typically used to specify heat output when expressed in Tons/day, where the use of the more modern term Watts is the simpler and more universal measure that should be used. Conversions from Tons to Watts are provided at the end of this paper.
A/c tons represent a truly archaic term. Needless to say, the rest of the world has been using the much simpler and more elegant metric system for the last 200 years. Only the following countries do not use the metric system: United States, Liberia, and Myanmar. Looks like Americans cannot cope with the simplicity of grams and kilograms. They struggle with fractions of feet, chains, rod and miles, instead of using simple millimeters, centimeters, meters and kilometers.
http://en.wikipedia.org/wiki/Metric_system
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Walter
www.rationality.net
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http://www.apcmedia.com/salestools/TEVS-5TXPED_R1_EN.pdf writes:

Amazing that APC is publishing such stupidity as this. This would flunk high school physics. Even a public school.
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Indeed. For those who didn't catch it, a ton of ice takes the same amount of energy to melt, regardless of how long it takes.
[Especially when you notice the other posting that says "of ice in 24 hours..."]
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Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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Chris Lewis wrote:

Careful! You might miss a high school physics question too. Unfortunately, a Refrigeration ton is is sometime a unit of power, and sometimes a unit of energy. As a unit of power, (in the US) it is 12000 BTU per HOUR, which is also approximately the amount of power required to melt one ton (2000 pounds) of ice per DAY. That is also called a "commercial ton of refrigeration".
As a unit of energy ("standard ton of refrigeration"), it is 288,000 BTUs, which is approximately the energy required to melt 2000 pounds of ice. (not a rate, so no time units here).
See:
http://en.wikipedia.org/wiki/Ton#Units_of_energy_and_power http://www.sizes.com/units/ton.htm#ton_of_refrigeration http://home.att.net/~numericana/answer/units.htm#othertons
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On Jul 12, 11:14 am, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

Yeah, it's shame that a company document that tauts itself as "Explanation........for IT Professionals" would contain such sloppy info
I guess that's one the benefits of wikipedia....peer correction
I was under the impression (or at least this is the way my circle of engineers referred to a/c capacity)
a "ton of a/c" was derived from that amount of heat required to be "removed" to generate a ton of ice....(since an a/c is a means to remove heat)
then (for the sake of "defining" a/c capacity) this quantity was spread over a 24 hr period to give a heat removal rate in BTU/hr
SO since the heat of fusion for water (from memory is ~144 btu / lbm) thus a ton of ice (water) needs a total heat removal of 288,000 btu
divided by 24hrs yields 12,000 btu / hr
so a one ton a/c unit has the heat removal capacity of 12,000 btu / hr
wrt to SI or Imperial units ......some things still haven't made the jump to SI (even in the metric world) :)
cheers Bob
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: > : > > A ton is equal to 12,000 BTUs
CY: Correction. that's 12,000 BTU per hour.
and is the amount of heat : > > energy required to melt : > > 2000 pounds (907kg) of ice in one hour.
CY: Wrong. Rate of heat required to melt a ton in 24 hours.
: : Indeed. For those who didn't catch it, a ton of ice takes the : same amount of energy to melt, regardless of how long it takes. : : [Especially when you notice the other posting that says "of ice : in 24 hours..."] : -- : Chris Lewis,
CY: However, a ton specifies the rate of 24 hours.
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On Wed, 11 Jul 2007 21:09:00 -0700, Walter R. wrote:

Horsepower is just as archaic, is not a part of the metric system, and the whole world has no problem using it.
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"Horsepower" is an extremely sloppy technical designator. How many different versions of horsepower are there, including the original one horse power? Nobody knows precisely what your refer to, when you are using the term "horsepower". The sales department and the technical departments have different ideas as to what constitutes a "horsepower". That's what happens when we use archaic descriptive terms. We should strive for precision in language. Why not use the universal and unambiguous Watt?
http://en.wikipedia.org/wiki/Horsepower
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Walter R. wrote:

Watts alone don't tell you how much *useful* work can be accomplished. For that you also need some sort of efficiency rating.
Chris
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Watts used as motor _output_ ratings. Efficiency is irrelevant to how much work you can produce. If the motor _produces_ 1Kw, that's how much work it can do, regardless of the efficiency.
As an example, much of the rest of the world doesn't use "HP" for gasoline engines - engines are rated in watts or kilowatts. It's output power.
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Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
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Chris Lewis wrote:

"Shaft", "Net" or "Belt" HP is output power, too...it doesn't matter what the units are, it's _where_ it's measured.
--
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My motor has a shaft and a belt. Do I need a net too? :)
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On Thu, 12 Jul 2007 18:11:56 -0000, Chris Lewis wrote:

I didn't know that. What are some of the countries where GASOLINE engines are rated in watts or kilowatts?
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Karl S wrote:

How about Germany? They also measure DIESEL engines' output in kW.
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On Fri, 13 Jul 2007 01:41:02 GMT, Beowulf wrote:

In Germany it's Pferdestrke, or PS.
I'm not sure about all diesel engines, that's why I emphasized GASOLINE. I know that many diesels, especially the gigantic ones they use on ships, in power plants, etc., were rated in kW. Like the ones from this interesting German company: http://www.manbw.com /
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