Capacity

The heating or cooling output of a system. It indicates how much heat energy an HVAC unit can add or remove per hour, usually expressed in BTU/h or tons (1 ton = 12,000 BTU/h). Capacity is a key spec for sizing equipment: a larger-capacity unit can condition a larger space. For cooling, capacity is the rate of heat removed from indoor air; for heating, it’s the rate of heat delivered to the air.