Step 1
Determine the amount of kilowatts. Find the kilowatt number on the appliance's label or the specifications page of the operator's manual. If neither the unit nor the manual displays kilowatts, look for the ampere (amp) and voltage rating. Multiply the amperes by volts by 1,000.
Step 2
Calculate the cubic feet per minute (cfm). Multiply the kilowatts by 3.413 by 1.0 for a 1-phase motor or 3.413 by 1.732 for a 3-phase motor. Record this number as the numerator, or the first number in a division equation. Multiply the difference between the temperature of the air after it leaves the heat source and the temperature before it enters the source by 1.08. Write this number as the denominator, or second number in a division equation. Divide the numerator by the denominator to obtain the cubic feet per minute.
Step 3
Convert the cubic feet per minute to liters per second (L/S). Divide the number of cubic feet per minute by 2.119 or multiply it by 0.471920717. One liter per second is the same as 2.119 cubic feet per minute.