Indoor Pool Dehumidifier — Humidity Control for Natatoriums, Spa Rooms, and Aquatic Centers

ASHRAE recommends 50–60% relative humidity for indoor pool spaces, with 55% RH and an air temperature 1–2°C above water temperature as the typical design target. Below 50% RH, evaporation rate accelerates (raising operating cost and chemical consumption) and swimmers feel cold when leaving the water due to evaporative cooling. Above 60% RH, the dew point approaches the temperature of cold building surfaces and condensation begins to form on glazing, fasteners, and structural steel.

Pool dehumidifier sizing is based on the evaporation rate from the water surface, not the room volume. The ASHRAE Applications Handbook gives a formula using pool surface area, the vapor pressure differential between water and air, and an activity factor (0.5 unoccupied, up to 1.0 competitive use). For most commercial pools, evaporation falls between 0.15 and 0.3 liters per m² of water surface per hour, or roughly 4–8 liters per m² per day. Multiply by water surface area to get the daily moisture load, then add ventilation air and occupant loads. We provide free sizing for any project — send your pool dimensions, water temperature, and target RH.

A pool dehumidifier needs three things a standard commercial unit does not always include: copper tube heat exchangers (not aluminum), corrosion-protected fin treatment, and a moisture-proof cabinet coating. Pool air is chemically aggressive — chloramines, hypochlorous acid, and trace HCl will attack standard aluminum fins and galvanized cabinets within 2–4 years. SHISHUO industrial GDH and GDH-CE units use copper coils with titanium foil fin treatment and sealed cabinet construction for this reason.

The SHISHUO Indoor Swimming Pool Dehumidifier line is floor-standing anti-corrosion construction across the full capacity range — from the compact GDH-60E for small hotel spas up to GDH-1440E for large aquatic centers. Floor-standing units are preferred for pool spaces because the cabinet can be positioned in an adjacent utility room and ducted through the pool room wall, keeping the copper coils and cabinet electronics away from direct pool-deck chloramine exposure. For projects that specifically require concealed overhead installation (some hotel guest pools with architectural constraints), our GDH-CE ceiling-mounted ducted range can be specified with the same anti-corrosion coil treatment — contact our sales team to discuss pool-specific configuration of the GDH-CE series.

Supply air should be directed along the glazing line and across any cold exterior wall surface. Window condensation is the most visible failure mode in indoor pool rooms, and continuous airflow over the glass surface prevents the room dew point from condensing there. Return air should pull from the warmest, highest-humidity zone — usually the ceiling above the deep end of the pool. This pattern is sometimes called "wash the windows, pull from the ceiling" and is the standard design pattern for natatorium HVAC.

All SHISHUO industrial models include continuous gravity drainage through a hose connection. In a pool room, the drain is typically routed to the deck floor drain or to a small condensate pump if the unit is located above the slab. Condensate from a clean dehumidifier coil is essentially distilled water and contains no chlorine — it can be discharged to the sanitary drain or, in some jurisdictions, reused as cooling tower make-up.

A standalone dehumidifier (SHISHUO GDH-CE or GDH industrial series) controls humidity only. Pool space heating and cooling, outdoor air ventilation (required by ASHRAE 62.1 for indoor air quality and chloramine dilution), and pool water heating are typically handled by separate equipment. For projects that need integrated dehumidification with heat recovery to the pool water, share your project specifications and we will discuss combined-system options. Most SHISHUO pool projects use a separate dehumidifier alongside an air handler with outdoor air and heating/cooling coils, which is the most flexible configuration for retrofits.

SHISHUO industrial GDH-CE and GDH units installed in correctly designed pool spaces — meaning the unit pulls from a ducted return rather than directly from the deck atmosphere, and the room is operated within ASHRAE 55% RH guidance — typically deliver 8–10 years of service before the heat exchanger requires inspection or replacement. Service life drops significantly in poorly ventilated rooms, in pools with elevated free chlorine levels, or where the unit is installed directly on the pool deck with intake air drawn from the wet zone.

Yes. The SHISHUO Indoor Swimming Pool Dehumidifier line holds CE and RoHS certifications, and all anti-corrosion construction — epoxy-coated copper condenser, stainless-steel-treated cabinet, titanium-foil coil fins — is designed for the chemically aggressive atmosphere of chlorinated pool rooms. Specific compliance documentation per model is available on request — contact our sales team and we will provide the certificate matching your destination market and project specification.