In the context of air conditioning, a ton refers to the unit of measurement used to express the cooling capacity of an air conditioning system. One ton is equal to the amount of heat that can be removed from a building or a space in one hour by an air conditioning system that has a cooling capacity of 12,000 BTUs per hour. The term “ton” is used because the cooling capacity of early air conditioning systems was based on the amount of ice that was melted by the system in a given time period, and it was believed that one ton of ice was equal to 12,000 BTUs of cooling capacity.

Today, the term “ton” is still commonly used to express the cooling capacity of air conditioning systems, even though most modern systems use refrigerant rather than ice to produce cooling. The size of an air conditioning system is often expressed in terms of tons, and it is typically based on the size of the space or building that the system is designed to cool. For example, a 3-ton air conditioning system would be suitable for a building or space that requires 36,000 BTUs of cooling capacity per hour.

It is important to properly size an air conditioning system based on the cooling needs of the building or space it is serving. An oversized system may be less efficient and may not properly dehumidify the air, while an undersized system may struggle to maintain a comfortable temperature and may run constantly, resulting in higher energy costs.