Sizing a Pool Dehumidification Unit – What to consider?
Dry-o-tron units, by Dectron, are designed specifically to suit the environment where the pool is located. Numerous factors are considered during the design of a unit. These factors include such things as; space and pool dimensions, window sizes and quantities, desired air changes/hour, pool water temperature, design air temperature, number of spectators, pool activity level and even water equipment (slides, fountains, etc.) All these factors plus more will affect the size of the Dectron unit. Changes to these factors after the Dectron unit has been installed can dramatically hinder the performance of the unit as well as shorten the lifespan. Further to that you run the risk of negatively affecting such things as; Air quality, comfort and operating costs. As well you have a higher chance developing mold and mildew and corrosion.
The relationship between the water and air temperature have a major impact on the size of the unit. There is roughly a 15% increase in evaporation rate when the pool temperature is higher than that of the air in the space. Below is a chart illustrating the relationship between these temperatures:
From an energy conversation standpoint, it is recommended the pool temperature be designed 2˚F lower than the ambient air temperature. This will reduce the evaporation rate of the pool and thus reduce the size of the equipment. Having said that, Dectron units can be designed to handle whatever temperatures the building owner desires, within reason. These temperatures need to be known at the time of design. The original design temperatures are included on the units nameplate.
Once a Dectron unit has been installed, the design temperatures must be maintained and not altered. The unit was specifically designed to maintain a relative humidity of 50% +/- at the design temperatures. By deviating from these temperatures you will increase the evaporation rate of the pool water and add a considerable amount of humidity load within the space. With this added load the unit will struggle to maintain the desired 50% RH and could cause health or structural problems. Below is a chart illustrating the growth rates of various bacteria and their relationship to humidity.
As you can see, it is important to occupants health to maintain a relative humidity between 40%-60%.
As humidity levels increase, if the space temperature isn’t increased likewise, the dew point temperature will also increase. This will cause condensation to form on cooler surfaces such as windows, exterior walls, steel structural members etc. This can cause a number of issues. Chloramines, a substance formed when chlorine combines with nitrogen-containing compounds such as sweat and urine are a bi-product of pools. Airborne chloramines have a strong affinity to pure water such as condensation. Condensation can accumulate considerable amounts of chloramines, which can make it acidic and corrosive. Prolonged exposure to chloramines can cause rusting on metals and possibly structural failure.
For further information and assistance with you dehumidification requirements, contact O’Dell today! CONTACT US