Expansion Tank Sizing Calculator ASME / ASHRAE

Size closed hydronic system expansion tanks using the ASME method. Covers chilled water, hot water, and glycol systems.

📈 System Parameters

Total fluid volume in piping, coils, and equipment
Static fill pressure at tank location; typically 10–20 psig
Relief valve setting minus 10%; typically 30–45 psig
Fill / cold temp; typically 40–60°F
Design operating temp; HHW 180–200°F, CHW 40–55°F

📚 Water Expansion Factors (ΔV/V)

Temp Range (°F)Water20% Glycol30% Glycol40% Glycol50% Glycol
50 → 1000.00160.00250.00300.00350.0042
50 → 1400.01380.01650.01800.01980.0220
50 → 1800.02990.03400.03650.03950.0430
50 → 2000.03860.04350.04650.05000.0545
50 → 2200.04810.05400.05750.06200.0670

Source: ASHRAE HVAC Systems & Equipment Handbook (expansion factor tables). Glycol values approximate — verify with manufacturer for exact concentration.

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  • ✓  ASHRAE 62.1 ventilation + CLTD/CLF/RTS load methods
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