Pool dehumidifiers are a fundamental component of creating a sustainable and healthy atmosphere in indoor pool environments. Dehumidification units are designed to balance the humidity dynamics of indoor swimming pools, thereby providing a comfortable and safe environment for visitors and staff. In this article, we will examine how pool dehumidifiers work, why dehumidifiers are so important for pools, and the key factors to consider when selecting the right unit for your indoor pools.
Humidity control not only preserves the structural integrity of the pool but also extends its service life. By improving indoor air quality, it enhances the satisfaction of guests and staff. The evaporation of water in swimming pools is a natural transition process that occurs from the water surface into the air. This process is greatly influenced by the temperature difference between the water and the air. The higher the water temperature, the greater the evaporation rate. Air movement above the pool, created by ventilation systems, can further accelerate evaporation. Ventilation systems remove saturated air from the water surface and replace it with drier air, leading to a more intense evaporation process.
The surface area of the pool also affects the amount of evaporation, with more water evaporating from pools with larger surface areas. Pool usage is another factor that influences evaporation. The movements of swimmers increase the water surface area and thereby accelerate evaporation.
As a result of evaporation, the pool water level gradually drops over time, requiring water to be regularly added to the pool. In an indoor pool without humidity control, the chemical balance of the pool can change due to evaporation, necessitating continuous adjustment of chemical levels. In an indoor pool, various methods such as pool covers and pool blankets can be used to reduce evaporation levels, enabling savings on water loss, dehumidifier energy consumption, and pool chemicals.
In an indoor pool environment where temperature and humidity control is not maintained, a lack of fresh air combined with a mixture of sweat, urine, and pool chemicals in the air creates an uncomfortable experience for guests and challenging conditions for staff working in these environments. Indoor pools without fresh air intake, where the air becomes stagnant, can pose health risks especially for individuals with respiratory problems such as asthma.
When chlorine evaporates along with pool water, it becomes acidic in the humid environment and can penetrate the building's walls and especially the drywall used in the space, threatening structural integrity. As a highly aggressive chemical, chlorine will begin to deteriorate cinder blocks, mortar joints, bricks, metal doors, and light fixtures at a much faster rate. In some cases, chlorine can react with silica in concrete, causing an alkali-silica reaction (ASR). ASR leads to the formation of expanding gels within the concrete, and this expansion can cause cracking and structural deterioration. The acidic effect of chlorine can cause erosion on the surfaces of concrete, mortar, and brick. Erosion increases the porosity of the material and allows water and other harmful substances to penetrate the structure more easily, thereby weakening structural integrity and potentially leading to damages that may require serious repairs over the long term.
Drywall, particularly used in suspended ceiling enclosures of indoor pools, is prone to absorbing moisture and can absorb water vapor when exposed to high-humidity environments. Due to the moisture-absorbing capacity of its gypsum and cardboard paper components, drywall swells by retaining water vapor in humid environments. The combination of high temperature and high humidity caused by lack of ventilation and humidity control on the cardboard paper, an organic component of drywall, provides an ideal breeding ground for the growth and proliferation of mold and fungi. The growth of mold, fungi, and bacteria can cause allergic reactions, rashes, coughing, and respiratory problems in people (especially children). This makes the pool experience not only uncomfortable for users but also potentially hazardous to their health. If uncontrolled condensation forms on the floor around the pool, slips and other accidents may also occur.
One of the significant problems experienced in indoor pools is condensation on windows that face the outside (atmosphere). When the temperature of the air inside the pool area is increased, it expands, and when cooled, it contracts. Warm air, which tends to hold more water vapor, condenses into liquid form when it hits cooler surfaces and reaches the dew point. The fogging of windows and, in advanced stages, condensation forming on all windows, walls, and even floors/ceilings, is fundamentally caused by the indoor air having a dew point higher than the surface temperature.
Optimal Humidity Balance for Your Indoor Pools: The Importance of Modern Dehumidification Technologies
Another parameter that must be kept under control in swimming pools is relative humidity (RH). High relative humidity increases the perceived air temperature, causing deterioration of comfort conditions for pool guests, creating a stuffy and uncomfortable atmosphere, shortness of breath, and shorter pool usage times for guests. Excessively high relative humidity in areas connected to the pool hall (showers, restrooms, changing rooms) can adversely affect users' health. It is important that the relative humidity is not so dry as to cause water to evaporate too quickly, nor at a level where the rapid evaporation of water from swimmers' bodies upon exiting the pool draws heat from the human body too quickly, causing swimmers to feel cold. VDI 2086, published by the Association of German Engineers (Verein Deutscher Ingenieure - VDI), which contains specific requirements and recommendations for HVAC systems in swimming pools, states that there should be a 2°C difference between the pool water and ambient temperature. Exceeding this difference increases energy consumption and pool water evaporation rate, while a smaller difference moves away from comfort conditions and causes the evaporation rate to decrease. The recommended ambient relative humidity range is 50% RH to 65% RH.
Heat recovery dehumidification air handling units designed with a mixture of fresh air and return air, used in large pools, are designed with an internal automation scenario that adjusts the mixing/fresh air ratio through dampers based on the seasonal effects of climate conditions on the indoor environment and daytime/nighttime pool usage rates. This ensures that energy management is the basis for achieving optimal conditions in the pool environment.
For smaller therapy pools, jacuzzis, thermal pools, and individual pools, indoor conditioning is targeted using external and compact dehumidifiers. When designing the right pool dehumidifier, the pool surface area, pool water temperature, ambient temperature, room volume, the number of people simultaneously in the pool, and the activity level of pool users become important factors. Since evaporation is higher in therapy pools, jacuzzis, and thermal pools, engineering calculations for dehumidifiers in these pools must be carried out very carefully. The heat transfer coil surfaces of any dehumidifier used in all pools that will come into contact with indoor air containing chlorine vapor must be coated with corrosion-resistant materials.
Blue Fin Coating: Blue Fin coating is a special type of coating used particularly in HVAC (Heating, Ventilation, and Air Conditioning) equipment such as heat exchangers and cooling coils. Blue Fin coating is applied to heat exchanger surfaces to provide extra protection against corrosion and improve the unit's efficiency. It is typically applied to aluminum or copper surfaces, protecting them against weather conditions, salt water, and corrosive pool chemicals such as chlorine. Blue Fin coatings form a thin protective film layer that extends the lifespan of metal surfaces and generally contain a polymer-based material. Blue Fin coating is a widely used option for dehumidifiers and other HVAC equipment used in pools. Blue Fin coating protects metal surfaces under harsh pool conditions, enabling units to last longer and require less maintenance. Additionally, by preserving heat transfer efficiency, it can optimize the equipment's energy consumption and thus provide long-term energy savings.
Cataphoresis: The cataphoresis process (Cataphoresis Treatment or Electrophoretic Coating) is a method used to apply protective coatings to metal surfaces. In this process, the part to be coated is placed as an anode or cathode in an electrolyte solution and an electric current is applied. The coating material is attracted to the metal surface by electrical charge, forming a thin, uniform, and smooth coating layer. The cataphoresis process is widely used for corrosion resistance in many industries, primarily the automotive industry. The use of cataphoresis on the cooling coils of pool dehumidifiers is preferred as an effective method for protecting the metal surfaces of cooling coils from corrosion caused by moisture, chlorine, and other chemical substances. Cataphoresis coating ensures long metal lifespan and improves the overall durability and efficiency of the unit. Cataphoresis-coated cooling coils are ideal for providing long-term protection in environments exposed to chemicals and high humidity levels, such as swimming pools. This coating method makes the coil surfaces more durable and long-lasting, reducing maintenance costs and requirements.
Pool mechanical rooms, which are located close to pools and typically underground with low temperatures and high relative humidity levels, are also among the areas that require the use of dehumidifiers. Thanks to wheeled mobile dehumidifiers that offer flexible usage, humidity in pool mechanical rooms can be stabilized, protecting environmental components against corrosion. Mobile dehumidifiers can easily adapt to varying needs and can be supplemented with additional dehumidifiers when necessary, providing flexible capacity utilization. This protects mechanical equipment from moisture and reduces the overall operating costs of the pool by safeguarding equipment from the harmful effects of humidity.
NKT – Humidity Control Technologies, with our expert engineering team, offers our customers energy-efficient, high-performance solution recommendations for the most suitable wheeled mobile dehumidifiers and wall-mounted compact dehumidifiers, as well as service and periodic maintenance for all pool and pool mechanical room dehumidifiers.