Expansion Tank Size Calculator
Hydronic System Expansion Tank
Size expansion tank for hot water heating system
Formula
Tank Size = Expanded Volume / Acceptance Factor | Expansion = Volume x 0.00041 x DeltaT
Frequently Asked Questions
Why do I need an expansion tank?
Water expands when heated. Without an expansion tank, pressure would build up dangerously in a closed system. The tank absorbs the expanded volume and maintains safe operating pressure.
How is expansion tank size determined?
Tank size depends on total system water volume, temperature range, fill pressure, and relief valve setting. The tank must absorb all expanded water while keeping pressure below the relief valve setting.
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