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Heat Pump Buffer Vessel Sizing

Minimum system volume for heat-pump defrost/cycling vs actual system volume, with buffer or volumiser sizing and 2-port vs 4-port configuration guidance.

Heat pump

kW

BS EN 15450:2007 band (12-35 L/kW) — see the calc's sourcing

Actual system volume

m
m
m
m
m
m
no.
L
L
L
L
L

From System Volume & Water Content's own engine

Configuration

Advisory only — does not change the sizing result

Enter the heat pump output and an actual system volume > 0
ensign.software · 28 October 2026The Ensign Toolbox