Convert a cooling load into chilled water flow. Enter kW, tons or Btu/h and the supply-return ΔT, for water or glycol, and see the flow in L/s, m³/h and gpm with a pipe velocity check.
SI: Q (L/s) = Load (kW) ÷ (cp × ΔT) × 1000/ρ ≈ kW ÷ (4.19 × ΔT °C)
US: gpm = Btu/h ÷ (500 × ΔT °F) = 24 × tons ÷ ΔT °F
At a 10 °F ΔT each ton needs 2.4 gpm; at 12 °F, 2.0 gpm. In SI, 1 kW at 6 K needs 0.040 L/s. A larger ΔT means less flow, smaller pipes and pumps, but the coils must be selected for it. Glycol carries less heat per litre than water, so the same load needs about 10–20% more flow.
Size the pipes with the Chilled Water Pipe Sizing Calculator, the pump with the Pump Head Calculator, and the chiller with the Chiller Tonnage Calculator. More on chilled water pipe sizing.
gpm = 24 × tons ÷ ΔT in °F, or in SI L/s = kW ÷ (4.19 × ΔT in °C). 100 tons at 10 °F ΔT needs 240 gpm; 350 kW at 6 °C ΔT needs 13.9 L/s.
2.4 gpm per ton at a 10 °F temperature difference, 2.0 gpm per ton at 12 °F and 1.5 gpm per ton at 16 °F.
Found a number that looks wrong, or a case the tool does not cover? Say so here — corrections are welcome and get answered.
No comments yet. Be the first to add one.