Heat Pumps and Electric Heating - Who knows the origin of "Tons" for AC?

Anyone? HVAC guys? Joe Average?

I know...............

I know...............

back in the 60's my dad ran a store in Hightstown NJ with a "not used in ~40 years"
"Ton" system in the very old building.

I know...............

would you care to share??? i understand 12,000BUTs is a TON. how the term TON came to apply to AC is unknown!

oh TY google

A ton of cooling capacity is the amount of cooling that would be provided by melting a ton of ice. Thus, a central air conditioning system that is rated as a 2-ton system would provide the same cooling as melting two tons of ice per hour

per the furnacecompare website

Edit: And why the heck are they 'British Thermal Units' anyway, why not American Thermal Units, or Smith Thermal Units, or even just Thermal Units?

that is a good start, but i suspect that statement has a serious flaw.
pretty obvious to me. anyone else see it?

I don't see a big flaw. A ton of cooling will remove enough heat to melt 1 ton of ice in one hour.

ok...even more TY to Coldfuse from the conversion site.

"Just wanted to provide background on the derivation for tons of refrigeration, and provide information on the similar SI standard.

The latent heat of fusion for ice is 144 BTU/lb. For one ton, that is 2000 lb x 144 BTU/lb, or 288,000 BTU. Refrigeration's roots are in the ice making industry, and the ice guys wanted to convert this into ice production. If 288,000 BTU are required to make one ton of ice, divide this by 24 hours to get 12,000 BTU/Hr required to make one ton of ice in one day.

This is simply the requirement for the phase change from liquid to solid -- to convert +32 deg F water into +32 deg F ice. As a practical matter, additional refrigeration is required to take city water and turn it into ice.

One BTU is the heat removal required to lower the temperature of one pound of water by one degree F. In SI units, kilocaries are used. One kilocalorie is the heat removal required to lower the temperature of one kilogram of water by one degree C. One ton of refrigeration is equal to 3024 kilocaries per hour. It is basically the 12,000 BTU/Hr divided by pounds per kilogram divided by 1.8 (to get from degrees F to degrees C)."


PHEW thats enuf for me!

I don't see a big flaw. A ton of cooling will remove enough heat to melt 1 ton of ice in one hour.

i don't think they replaced 1 ton of ice in my dad's ~800sf store every hour LOL I'm lucky if i take a burger out of the freezer, and it defrosts in 1 hour. LOL
it would take days to melt

Matt,

I agree that if you really want to understand this Google can be your best friend.

I have been doing this type of work long enough that I was fortunate to have been able to work on an ice bank a/c system in a church that was installed in the early fifties.
I do not recall the exact sizes but there was about a three hp compressor that was used to make ice in a several thousand gallon water tank.
It would take many days to freeze plates in the bank and when they turned on the circulating pumps before church it would only last for a couple of hours to cool the chapel for the service.

Ice banks are actually still used.
A honey processing plant I serviced had an ice bank for the cooling in the pasteurizing process.
They looked at replacing it with direct expansion cooling but they would have needed a system of such a large capacity that it would be impractical.
Their system would take about 16 hours to freeze the ice bank and less than two hours to melt down the ice for the days processing.

So, here's he answer.

The latent heat of fusion for ice is 144 BTU/lb. For one ton, that is 2000 lb x 144 BTU/lb, or 288,000 BTU. Refrigeration's roots are in the ice making industry, and the ice guys wanted to convert this into ice production. If 288,000 BTU are required to make one ton of ice, divide this by 24 hours to get 12,000 BTU/Hr required to make one ton of ice in one day.

This is simply the requirement for the phase change from liquid to solid -- to convert +32 deg F water into +32 deg F ice. As a practical matter, additional refrigeration is required to take city water and turn it into ice.

One BTU is the heat removal required to lower the temperature of one pound of water by one degree F. In SI units, kilocalories are used. One kilocalorie is the heat removal required to lower the temperature of one kilogram of water by one degree C. One ton of refrigeration is equal to 3024 kilocaries per hour. It is basically the 12,000 BTU/Hr divided by pounds per kilogram divided by 1.8 (to get from degrees F to degrees C).

Anything else you want to know Matt?

Jeez Jarredsdad,
At least I gave credit to the guy I stole it from...lol j/k!!
Kinda funny tho, I just moved from VA last year, but I grew up outside Troy...Ohio.

Who stole it from someone else.

The OK State link I originaly read it at didn't come up, so I just copy/pasted this which is correct. And, is fast, less typing, than pulling out of the depths of my brain and referance manuals and actually typing it.

I didn't take it from your post, maybe your source. ;)

Thanks for the replies! Keep them coming, very interesting!
I can see the described uses as being a lot different than my dads store.
A delivered ton of ice would be covered with an insulation blanket at night, and radiate cool air during business hours. I expect it would take several days to melt it.
His store was a butcher shop, so ice was also needed for the ice box for meat.
Not much counter space to cool.

So, here's he answer.

The latent heat of fusion for ice is 144 BTU/lb. For one ton, that is 2000 lb x 144 BTU/lb, or 288,000 BTU. Refrigeration's roots are in the ice making industry, and the ice guys wanted to convert this into ice production. If 288,000 BTU are required to make one ton of ice, divide this by 24 hours to get 12,000 BTU/Hr required to make one ton of ice in one day.

This is simply the requirement for the phase change from liquid to solid -- to convert +32 deg F water into +32 deg F ice. As a practical matter, additional refrigeration is required to take city water and turn it into ice.

One BTU is the heat removal required to lower the temperature of one pound of water by one degree F. In SI units, kilocalories are used. One kilocalorie is the heat removal required to lower the temperature of one kilogram of water by one degree C. One ton of refrigeration is equal to 3024 kilocaries per hour. It is basically the 12,000 BTU/Hr divided by pounds per kilogram divided by 1.8 (to get from degrees F to degrees C).

Anything else you want to know Matt?

WHEEEU! that makes my head hurt! i'll add that to my collection of unused information. thanks!