Why air conditioning are rated in Tons not in KW or KVA?

Air conditioners are rated in tons because it's a traditional unit from the refrigeration industry that indicates how much heat the system can remove, not how much power it uses. One ton equals the heat needed to melt one ton of ice in 24 hours, or 3.5 kW of cooling. Though the actual power consumption (in kW or kVA) is important, tonnage gives a more practical idea of cooling capacity.

Full Explanation:

Air conditioners are rated in tons instead of kilowatts (kW) or kilovolt-amperes (kVA) because tonnage represents the cooling capacity, which is the main function of an air conditioner. The term “ton” comes from the early days of refrigeration when ice was used for cooling. One ton of refrigeration is defined as the amount of heat required to melt one ton (2000 pounds) of ice in 24 hours. This equals 12,000 BTU/hr (British Thermal Units per hour), or about 3.5 kW of cooling power.

This historical unit stuck around because it's a practical way to estimate cooling needs in homes, offices, or commercial spaces. For example, a 1-ton AC can handle the cooling load of a small room, while a 5-ton AC may be used in a large hall or office. It directly reflects how much heat the AC can remove, making it easy for installers and users to understand and choose the right size for their space.

On the other hand, kW and kVA are units of electrical power, not cooling performance. kW tells you how much electricity the AC consumes, while kVA includes both real and reactive power (useful for sizing generators and transformers). While manufacturers may mention kW for energy consumption or efficiency (like EER or COP), tonnage remains the standard for specifying cooling capacity.

Historical Context:

Before modern air conditioning, ice was used to cool spaces. One ton of ice melting over 24 hours removes a specific amount of heat, which was then defined as a "ton of refrigeration". 

Directly Related to Cooling:

The ton unit directly relates to the cooling capacity of the AC unit, indicating how much heat it can remove per hour, making it a practical and easily understood measure for consumers. 

Avoiding Confusion:

Using "tons" avoids confusion with electrical power (kW or kVA), which are related to the energy consumption of the unit, not its cooling output. 

Industry Standard:

While kW and kVA are important for electrical calculations (like determining breaker size), the "ton" remains the standard for specifying the cooling capacity of air conditioners.

In summary, air conditioners are rated in tons because it gives a clear and standardized measure of cooling output, which is the most important function of the system.