How to Size a Chiller

Medical Chillers from BV Thermal Systems

Labs, Plastics, Lasers, Semiconductor, Medical, Pharmaceutical, Chemical, the list could go on and on.  What all of these industries have in common is they all require a chiller at some point in the process.  Determining the size of the chiller required is as simple as following a formula.  As long as you have a few facts, it may be done without being an expert.  However, if you re unsure, please do not be afraid to contact us, we’d love to assist you. 

How to Size a Chiller

There is a single and easy to follow formula for determining the size of chiller you require. However, there are a few factors you must know before you begin:

  • The incoming water temperature
  • The water temperature you require
  • The flow rate

General sizing formula:

  1. Calculate Temperature Differential (ΔT°F) ΔT°F = Incoming Water Temperature (°F) – Required Chill Water Temperature
  2. Calculate BTU/hr. BTU/hr. = Gallons per hr x 8.33 x ΔT°F
  3. Calculate tons of cooling capacity Tons = BTU/hr. ÷ 12,000
  4. Oversize the chiller by 20% Ideal Size in Tons = Tons x 1.2
  5. You have the ideal size for your needs

For example, what size chiller is required to cool 10 GPM from 72°F to 58°F?

  1. ΔT°F = 72°F – 58°F = 14°F
  2. BTU/hr. = 10 gpm x 60 x 8.33 x 14°F = 69,972 BTU/hr.
  3. Ton Capacity = 69,972 BTU/hr. ÷ 12,000 = 5.831 Tons
  4. Oversize the chiller = 5.831 x 1.2 = 6.9972
  5. A 6.9972 or 7-Ton chiller is required

It is that simple.  If you have any questions, or would like a quote customized to meet your specific needs, just complete the form below.