Why AC is Measured in Ton?

My father once shared with me the fact on why are air conditioners measured in tons. Before the mechanical refrigerator was in use, people used to cut ice from water bodies in winter and store them to use in summer for cooling buildings. So when Willis Carrier invented AC, ton was used as a cooling system to rate the cooling capacity. 

Why Are AC Units Measured in Tons?

Air conditioners are measured in tons to indicate their cooling capacity, with one ton equaling the cooling power needed to melt one ton of ice in a day. This unit dates back to the early 20th century when ice was commonly used for cooling. 

Engineers found that a ton of ice melting over 24 hours equated to a specific amount of cooling power. This is why the term is still used as a standard unit, providing a clear reference point for consumers to gauge cooling efficiency. I hope now you have understood why AC calculation in ton is practiced even now.

What is a Ton?

A "ton" in air conditioning refers to the cooling capacity that is equal to the heat required to melt one ton (about 2000 pounds) of ice in 24 hours. So by now, you must have understood why AC in ton is used.

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With the heat waves coming in India, most of us want to fight the warm summer by installing an AC at home. When choosing an AC, you need to be thorough about AC capacity in ton. The ton helps you understand how cool you want your room. 

When I was young I remember my father taking me to the store and asking the service provider to show a 2 ton AC. At that time, I had very little knowledge about tons. I kept wondering why AC is measured in ton. Now, that I am all grown up, I know the answer to why AC capacity in ton is measured. I will share the information regarding this.

Why AC capacity is measured in ton?

The aspect of why is AC measured in tons is very interesting. Ton in AC is compared to the cooling effect we get from 1 ton of ice. So, the power of 1 ton of ice is equivalent to 1 ton of AC. 

Let us understand how heat is absorbed by AC as per FPS. 1 ton is equivalent to 2000lb in the FPS system. The latent heat of ice would be 144 BTU/lb (BTU is a British thermal unit).  So, the ice starts melting at 144 BTU of heat.

So, the heat absorbed by 1 ton of ice or AC would be 2000×144=2,88,000 BTU of heat in 1 day.

To understand how much heat could be absorbed in an hour we need to divide by 24.

2,88,000÷24=12,000 BTU/hour

So, 1 ton air conditioner absorbs 12,000 BTU in 1 hour. So a 4-ton air conditioner can absorb 4×12,000=48,000 BTU heat in 1 hour.

Keeping the physics and maths, I would suggest you decide on a ton as per the size of the room. Don't try to go for a lesser ton just for a concession on pricing. The room won't be cooling faster if the AC ton doesn't comply with the size of the room. 

This was all about AC capacity in ton. I hope you find this informative.

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