Estimate chiller flow or cooling load from a positive fluid temperature rise, or calculate US GPM per refrigeration ton directly. Water uses the 500 approximation; glycol uses manufacturer density and specific heat at the stated concentration and mean fluid temperature.

Estimate flow from heat load and temperature rise.

Heat-transfer estimate using US gallons. Check equipment flow limits; glycol properties must match the fluid concentration and mean temperature.

Difference between return and supply temperatures; no 32-degree offset.

Related Calculators

GPM Per Ton Formula

The following ratio gives US gallons per minute per refrigeration ton from measured flow and cooling load. For the heat-transfer modes, Qheat = 60ฯcp ร— GPM ร— ฮ”TยฐF = 12,000 ร— tons. Water uses 60ฯcp โ‰ˆ 500, so GPM/ton โ‰ˆ 24/ฮ”TยฐF.

G = (Q) / (T)

Variables:

  • G is the US GPM per refrigeration ton
  • Q is the total flow rate in US gallons per minute (GPM)
  • T is the cooling load in refrigeration tons (1 ton = 12,000 BtuIT/h)

To calculate the GPM per ton, divide the total flow rate by the total tons of cooling.

What is GPM Per Ton?

GPM per ton is a measure used in HVAC (Heating, Ventilation, and Air Conditioning) systems to determine the flow rate of water required per ton of cooling. This ratio describes flow relative to thermal load; it does not by itself establish system efficiency or equipment flow limits. One ton of cooling is equivalent to the amount of heat required to melt one ton (2000 pounds) of ice in a 24-hour period, which is approximately 12,000 BTUs per hour. For water at a 10ยฐF temperature rise, the approximation gives 2.4 US GPM/ton. Glycol density and specific heat vary with composition and temperature. Use manufacturer properties and equipment flow limits; higher temperature rise does not automatically mean greater efficiency.

How to Calculate GPM Per Ton?

The following steps outline how to calculate the GPM per ton.

  1. First, determine the total flow rate (Q) in gallons per minute (GPM).
  2. Next, determine the total tons of cooling (T).
  3. Finally, calculate the GPM per ton using the formula G = Q / T.
  4. Choose Flow per ton to check this direct ratio. The other modes calculate flow or cooling load using temperature rise and fluid properties.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Total flow rate (Q) = 300 GPM

Total tons of cooling (T) = 100, giving 300 / 100 = 3 US GPM/ton. With water and a 10ยฐF rise, the heat-transfer estimate for 100 tons is instead 240 US GPM.