What size blower motor do I need?

The rule of thumb is for the blower to produce at least 400 CFM of air per minute. There is a two ton system with 880 cfm. The blower motor is usually about 1/3 HP.The thumb rule is that the blower must produce 440 CFM (cubic feet per minute) of air per tonne. In a two-ton system that is 880 cfm. This is usually calculated around a 14-13 hp blower engine.