Calculating Cooler Chilled Water Flow with a Thermometer

stock-photo-several-water-pumps-with-large-electric-motors-390544678Tools you’ll need

  • Thermometer
  • Calculator
  • Formula
  • Brain

First- determine the capacity of the machine a %100 load.

(Example: 20 tons)

Second- measure the temperature drop (Delta T)through the cooler with the chiller running at %100 capacity.

(Example: 60 degrees in, minus 48 degrees out = 12 degrees Delta T.)

Third- use the following formula:

Tons × 24 ÷ Delta T = Gallons per minute (GPM)

Example- (20 tons × 24)= 480 ÷ 12 = 40 Gallons per Minute (GPM)


Patrick is Zen HVAC’s diagnostic and training guy. Patrick started in the trade the day he left technical school and never looked back. He's served in various technical and training roles in the HVAC industry but specializes in system troubleshooting and diagnostics, retro commissioning, and technical training. His moto: If I can understand it, anybody can. Patrick uses the Zen common sense approach to teach Patrick’s Likes- His Wife, kids and dog. Old pickup trucks. Hiking. The industrial Revolution. Patrick’s Dislikes- Taking work too seriously. Anything unintuitive. Emoticons :( Patrick’s Favorite famous person- Theodore Roosevelt “I am only an average man, But I work harder at it than the average man" Famous Patrick Quote- “Well, that was stupid of me”

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