In the context of HVAC (Heating, Ventilation, and Air Conditioning) systems, tonnage refers to the cooling capacity of an air conditioning unit. It is a unit of measurement used to quantify the amount of heat an air conditioner can remove from a space in a given time.
The term "ton" in this context is derived from the historical use of ice as a cooling medium. In the past, ice was used to cool buildings, and the cooling capacity of an air conditioner was measured by how much ice (in tons) it could replace in a day. This measurement convention has persisted even though modern air conditioners do not use ice.
One ton of cooling capacity is equivalent to the amount of heat required to melt one ton (2,000 pounds) of ice in a 24-hour period. It represents a cooling capacity of 12,000 BTU (British Thermal Units) per hour. BTU is a unit of energy, and it measures the amount of heat required to raise or lower the temperature of a substance.
For example, a 2-ton air conditioner can remove 24,000 BTU of heat per hour from the space it is cooling, while a 3-ton unit can remove 36,000 BTU per hour. The tonnage of an air conditioner is typically mentioned in product specifications to help determine the appropriate unit size for a specific space.
It's important to note that selecting the right tonnage for an air conditioner depends on various factors, including the size of the room, insulation, climate, and other environmental conditions. Consulting with HVAC professionals or using load calculation methods can help determine the appropriate tonnage for efficient and effective cooling or heating of a space.