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💧 GPM Calculator
HVAC Chilled Water & Condenser Water Flow Rate Tool
Water Flow Calculation Results
Required Water Flow Rate:
0 GPM
Heat Rejection (BTU/hr):
0 BTU/hr
Flow Rate Per Ton:
0 GPM/Ton
Understanding GPM in HVAC Hydronic Systems
GPM stands for Gallons Per Minute, which quantifies the volumetric flow rate of chilled water or condenser water circulating through pipes, evaporators, and cooling towers.
- Standard Formula: Hydronic flow rate is calculated using
GPM = (Tons × 24) ÷ ΔTorGPM = BTU/hr ÷ (500 × ΔT). Master chiller plant automation on our JCI Classes Main Portal. - Chilled Water Rule of Thumb: At a standard 10°F temperature differential ($\Delta T$), a chiller requires 2.4 GPM per Ton of cooling.
- Condenser Water Rule of Thumb: Condenser loops account for compressor heat rejection and typically require 3.0 GPM per Ton based on ASHRAE Hydronic Design Standards.
Frequently Asked Questions (FAQ)
Q1. What is the standard GPM per Ton for Chilled Water systems?
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For standard chilled water systems operating at a 10°F Delta T (e.g., 44°F supply and 54°F return), the rule of thumb is 2.4 GPM per Ton.
Q2. Why is Condenser Water GPM higher than Chilled Water GPM?
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Condenser water must remove both the heat absorbed from the building and the electrical work energy heat added by the compressor. Therefore, it requires approximately 3.0 GPM per Ton (for a 10°F ΔT).
Q3. What is Delta T (ΔT) in hydronic calculations?
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Delta T ($\Delta T$) is the temperature difference between the entering water temperature (EWT) and leaving water temperature (LWT) at the chiller evaporator or condenser barrel.