Cold Plunge System Designer

Model the whole loop: tub heat gain, chiller capacity, pump operating point, filter restriction and plumbing diameter.

1. Tub & temperature

Water volume (gal)

Tub type

Starting water (°F)

Target water (°F)

Worst expected ambient (°F)

Desired pull-down (hours)0 = no time target.

2. Heat gain

Tub insulation

Cover

Location

Sun exposure

Exterior color

3. Plumbing & filtration

Hose / pipe ID

Total straight length (ft)

90°-equivalent elbows

Static head (ft)Closed recirculation loops usually have little true static head.

Filter preset

4. Pump

Pump

Pump installation

Tub length (in)

Tub width (in)

Tub height (in)

Safety: water + electricity is hazardous. Use manufacturer-approved installation, GFCI/RCD protection, correct grounding, outdoor-rated equipment where required, and never enter water with unsafe energized equipment.

What the calculator does not claim

It does not predict medical outcomes, sanitation performance, electrical-code compliance or exact manufacturer warranty suitability. Where product pressure-drop or low-temperature capacity data are incomplete, the engine uses bounded uncertainty and downgrades confidence rather than pretending the value is exact.