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Condenser Water Flow Rate

Also known as 3 GPM per ton

V˙=Q˙⋅HRFρwcw ΔT\dot{V} = \frac{\dot{Q} \cdot \mathrm{HRF}}{\rho_w c_w \, \Delta T}
sig figs

Worked example: 250 kW, HRF 1.2, 15 L/s → 4.785 K range. Press Try an example to run it live, then adjust anything.

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Where Condenser Water Flow Rate fits

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Hydronic Heat Transfer (Water)
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See also

Hydronic Heat Transfer (Water): Both use condenser water flow and condenser water ΔT.Chiller Heat Rejection: Both use heat rejection factor.Glycol Loop Heat Transfer (Capacity Derate): Both use condenser water ΔT.Chiller Efficiency (kW per Ton): Both use evaporator load.Energy Efficiency Ratio (EER): Both use evaporator load.Refrigerant Mass Flow Rate: Both use evaporator load.
1 more relatedTons of Refrigeration from BTU/hr: Both use evaporator load.
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Condenser Water Flow Rate explained

HRFQV̇ΔT

A cooling tower has to dump more heat than the building put into the chilled water, because the compressor's own electrical input ends up in the refrigerant too. The heat rejection factor accounts for that: about 1.25 for a typical electric chiller (12,000 BTU/hr of cooling plus roughly 3,000 BTU/hr of compressor work = 15,000 BTU/hr rejected per ton), 1.15–1.20 for a very efficient machine, and 1.7–1.8 for an absorption chiller, which is why absorption towers are so much larger.

Run one ton through the arithmetic at a 10 °F tower range: 15,000 ÷ (500 × 10) = 3.0 gpm, and there is the industry's favourite rule, 3 gpm per ton, standing on ASHRAE's 85 °F/95 °F condenser design. Widen the range to 15 °F and you need only 2 gpm per ton, which saves pump horsepower but costs tower approach; that trade-off is the whole subject of variable-flow condenser design. On the water-treatment side, ΔT and flow set the cycles of concentration you can hold: every 10 °F of range evaporates roughly 1 % of the circulating flow, so a 300 gpm tower at 10 °F range boils off about 3 gpm and must be bled and inhibited accordingly, or the tubes scale and the approach quietly walks away from you.

Condenser Water Flow Rate formula

V˙=Q˙⋅HRFρwcw ΔT\dot{V} = \frac{\dot{Q} \cdot \mathrm{HRF}}{\rho_w c_w \, \Delta T}
Where
  • V˙\dot{V}= Condenser water flow (L/min)
  • Q˙\dot{Q}= Evaporator (cooling) load (W)
  • HRF\mathrm{HRF}= Heat rejection factor
  • ΔT\Delta T= Condenser water ΔT (C°)
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Refrigeration capacity and efficiency

6 formulasTons, COP, EER and kW per ton — the four ways the trade states the same chiller performance, and how to convert between them.

Revised 31 October 2026
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formula.expert. (2026, October 31). Condenser Water Flow Rate Formula & Calculator. https://formula.expert/solvers/condenser-water-flow-rate

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