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EGW05-SWHPEG-20140724
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Diffusers for supply ducts located overhead (as opposed to under the deck) must be sized such that the supply air will be
thrown all the way to the deck and wash the entire wall surface from supply duct to the floor.
As a rule, directing the supply air at or across the pool surface increases the evaporation rate. To control the buildup of
chloramines at the surface of the pool, some air may be directed at the pool surface. Supply outlets should not discharge
directly onto surfaces where drafts may be created that will blow on swimmers walking along the edges of the pool.
Spectators should have supply air directed toward their faces.
Air Connections to PoolPak™
PoolPak™ outside air intake and exhaust air openings may have rain hoods if the unit is mounted outdoors. Rain hood
locations are illustrated on the unit arrangement drawings. The intake and exhaust should be screened to prevent the
entrance of foreign matter and arranged to avoid recirculation of exhaust and outside air. Also, when auxiliary gas heat is
selected (in an outside installation), a combustion air louver or rain hood is provided.
Supply, return, outside, and exhaust air ductwork connections over 5 feet long must be supported to avoid damage
to unit. Short, flexible connections of rubber or canvas can be made between the return duct and the unit to eliminate
vibration transmission through the duct.
PoolPak™ International does not recommend the use of equipment rooms or locker rooms as return or supply air
plenums due to the potential of corrosion for components installed in the room. The return air duct should always
connect the pool enclosure to the return air connection of the PoolPak™ unit(s).
Other Air-side Considerations
A duct heater (hot water coil, electric, or gas) may be installed in the supply duct to provide auxiliary space heating.
Be sure that the additional air pressure drop across the heater is accounted for in the unit fan selection. These heating
components must be designed for use in swimming pool environments.
Maintain the poolroom at a slightly negative pressure. This will minimize moisture and chemical odor migration to other
spaces. The exhaust fan should be sized for about 5-10% greater CFM than the amount of outside air being introduced
into the space. Ducts can be fabric, aluminum, PVC, or galvanized steel. Even though “dry air” is being supplied back
to the pool, do not use duct board or similar materials. If the PoolPak™ unit is installed in an area that is below the
natatorium’s dew point temperature, the ducts may require insulation, pitching and drainage.
Continuous vapor barriers are required between the poolroom and all other interior and exterior spaces because of the
high dewpoint in the poolroom all the time. Care must be taken during design and installation to avoid gaps in the
vapor barriers or building damage may result. For more information, see the
PoolPak™ Educational Library articles
“Efflorescence, What Causes It and How Do You Remove It?” and “Vapor Barriers In Natatoriums”
Windows and exterior doors must be selected with adequate thermal insulation (including thermal breaks) to minimize
condensation on their interior surfaces even if the supply air is directed across these components. Doors and windows
must also have as low an air leakage as possible. Although the space will be maintained at a slightly negative pressure,
cold air leaking into the space from poorly sealed openings will negate all of the effects of good thermal insulation.