How to Calculate Evaporator Sizing

Evaporators work like air conditioners or chillers.
••• window air conditioner image by Aaron Kohr from

Like similar Heating, Ventilation and Air Conditioning (HVAC) appliances, an evaporator pumps a refrigerant to lower the temperature. Larger evaporators cool larger spaces. Manufacturers size evaporators in terms of tons, a unit of power equal to 12,000 British Thermal Units (BTUs) per hour. Calculate this size from the evaporator's temperature range, which describes the fluid's temperature drop, and the volumetric flow rate, measured eventually in pounds of water per hour,

    Subtract the evaporator's outgoing temperature from its incoming water temperature. If you want water to enter the evaporator at 60 degrees Fahrenheit and leave at 46 degrees Fahrenheit: 60 - 46 = 14.

    Multiply the answer by your proposed volumetric flow rate, measured in gallons per minute. If the evaporator must move 400 gallons per minute: 14 x 400 = 5,600.

    Multiply the answer by 500: 5,600 x 500 = 2,800,000. This answer is the evaporator's size, measured in BTUs per hour.

    Divide the answer by 12,000: 2,800,000 / 12,000 = 233.33. This answer is the evaporator's size in tons.

Related Articles

How to Calculate Tons of Cooling for a Cooling Tower
How to Calculate Volume of a Rectangular Prism
How to Calculate Fan Output
How to Find the Volume of a Sphere in Terms of Pi
How to Calculate the Volume of Water to Fill a Rectangular...
How to Convert mm Hg to in Hg
How to Find Partial Pressures
How to Convert From BTU to Fahrenheit
How to Figure GPM Water Flow on an Existing Chiller
How to Calculate Refrigerant Amounts
How to Convert CV to GPM
How to Calculate Cubic Inches in a Cylinder
How to Calculate Temperature From BTU
How to Calculate Sides of a Triangle
How to Calculate the Volume and Circumference of a...
How to Convert KPa to Liters Per Minute
How to Calculate Condensate Flow From AC Units
How to Convert Steam Flow to Megawatts
How to Calculate KVA to MVA
How to Convert Specific Gravity in Weight