A ton of refrigeration (commonly abbreviated as TR) is a unit of power used in some countries (especially in North America) to describe the heat-extraction capacity of refrigeration and air conditioning equipment. It is defined as the heat of fusion absorbed by melting 1 short ton (2,000 lb; 0.893 long tons; 0.907 t) of pure ice at 0 °C (32 °F) in 24 hours.[2] It is equivalent to the consumption of one ton of ice per day and originated during the transition from stored natural ice to mechanical refrigeration. A refrigeration ton is approximately equivalent to 12,000 BTU/h or 3.5 kW. Air-conditioning and refrigeration equipment capacity in the U.S. is often specified in "tons" (of refrigeration). Many manufacturers also specify capacity in BTU/h, especially when specifying the performance of smaller equipment.Posted on May 29 2013 by When we talk about “tons” of air conditioner capacity, the expression refers to the weight of a quantity of ice that would provide the equivalent amount of cooling.

Before modern air conditioning, buildings were cooled with ice harvested from frozen lakes. A few years ago, a HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. rater student in a class I taught told a funny story. He was an HVAC(Heating, ventilation, and air conditioning). contractor and said he was installing a new air conditioner for an elderly woman. As he was explaining things to her, he mentioned that they would be installing a 4-ton unit. "How are you going to get something so big into my back yard?"HVAC and home energy pros find this story funny because when you say an air conditioner is 4 tons, we know we're not talking about the weight of the equipment.

(Fro now, let's ignore the issues of nominal vs. actual capacity and AHRI derating.) (A BTU is a British Thermal Unit, approximately the amount of heat you get from burning one kitchen match all the way down.) tax credit for new ac unitsFor most people, though, 4 tons means 8,000 pounds.ac window unit horizontal It's cold enough to start harvesting, so get out your ice sawbest portable ac units reviews Most pros also know how such a common term as “ton” has turned into a bit of HVAC jargon. A Green Homes America article quotes ice production figures from a 19th-century journal, Ice and Refrigeration, indicating that the 1890 crop from the Hudson River was about 4 million tons. The latent heat of fusion When ice is below freezing and it absorbs heat, its temperature increases.

When ice is at its melting point, 32°F, and it absorbs heat, its temperature doesn't change. So if you've got a pound of ice at 32°F, you put 143 BTUs into it to melt it completely. Then it takes only 180 more BTUs to raise the temperature of that pound of water from 32°F to 212°F, the boiling point. Anyway, getting back to our main discussion: if you have a ton of ice, it takes (143 BTU/lb) x (2000 lbs) = 286,000 BTUs to melt it completely. Somewhere along the line, though, someone decided to use 1 day — 24 hours — as the standard time reference here. We've been talking about “tons of cooling” for a centuryPeople in the industry start using it, and then the professional organizations make it official. An architecture website has a quote from 1912 that claims the American Society of Mechanical Engineers standardized it. It sounds likely, but their numbers don't work out, so I'm gonna go with Honest Abe (see image below) on this one and remain skeptical (until someone in the comments shows me what's wrong with my thinking anyway).

And if you figure out what “heat of zaporization” is, let me know!Commercial refrigeration systems in the US are mostly rated in tons of refrigeration and this term is used widely in other parts of the world. However, outside the US, cooling systems may be normally specified in kW (or MW) or in Btu/h. The roots for refrigeration are in the ice making industry, and the ice manufacturers wanted an easy way of understanding the size of a refrigeration system in terms of the production of ice. If 288,000 Btu are required to make one ton of ice, divide this by 24 hours to get 12,000 Btu/h required to make one ton of ice in one day. This is the requirement for the phase change from liquid to solid — to convert water at 0°C (+32°F) into ice at 0°C (+32°F). As a practical matter, additional refrigeration is required to take water at room temperature and turn it into ice. To be specific, one ton of refrigeration capacity can freeze one short ton of water at 0°C (32°F) in 24 hours.

So, a ton of refrigeration is 3.517 kW. This is derived as follows: The latent heat of ice (also the heat of fusion) = 333.55 kJ/kg = 144 Btu/lb One short ton = 2000 lb Heat extracted = 2000 x 144/24 hr = 288000 Btu/24 hr = 12000 Btu/hr = 200 Btu/min 1 ton refrigeration = 200 Btu/min = 3.517 kJ/s = 3.517 kW = 4.713 HP A much less common definition is: 1 tonne of refrigeration is the rate of heat removal required to freeze a metric ton (1000 kg) of water at 0°C in 24 hours. Based on the heat of fusion being 333.55 kJ/kg, 1 tonne of refrigeration = 13,898 kJ/h = 3.861 kW. Thus, 1 tonne of refrigeration is 10% larger than 1 ton of refrigeration. Another unit of measure is the calorie which is the amount of heat removal required to raise or lower the temperature of one gram of water by one °C. A kilo-calorie is the amount of heat required to raise or lower 1 kg of water by 1°C. One ton of refrigeration is equal to 3024 kilo-calories per hour. This is 12,000 BTU/ h divided by 2.204 (pounds per kilogram) divided by 1.8 (°C to °F).