How Is HVAC Designed for a Therapy and Warm-Water Pool?

I start therapy pool HVAC design by quantifying just how much more moisture the hot water produces. Using the pool's actual operating temperature — often 90 to 94 degrees — the evaporation calculation typically lands near double the lap-pool rate per square foot. That number sizes the dehumidification equipment, and I add margin for the reality that therapy pools run long hours with continuous gentle agitation from users. The ventilation rate still meets code minimums, but ventilation alone cannot carry this moisture load — the dedicated dehumidification system does the real work. Undersizing here shows up fast: within months, not years.

Therapy pool users are often elderly, injured, or managing chronic conditions — they experience drafts and temperature swings more acutely than lap swimmers. I design the air distribution for imperceptible air movement at occupant level, hold tight temperature control with minimal swing, and keep the deck and transition areas warm so the walk from locker room to pool never chills anyone. Radiant floor heating in the deck area is worth considering: warm floors under wet feet transform the comfort experience and add no air movement at all. Every comfort decision is judged from the perspective of a frail person in a swimsuit.

A therapy pool HVAC design is ready when it clears this checklist. Hot water forgives nothing — the moisture load, the comfort demands, and the envelope stress are all at their maximum here. • Dehumidification sized for hot-water evaporation rates, roughly double a lap pool's load • Room air held slightly above water temperature with tight, stable control • Low-velocity, draft-free air distribution with no supply jets crossing the pool • Separate zoning from cooler pool areas with independent temperature and humidity control • Heat recovery from dehumidification returned to the pool water to offset high energy costs