Specifications

24
Natatorium DesigN maNual
• Preheat the outdoor air to 65°F to avoid condensation
problems. Seresco’s glycol heat recovery loop is a
good means to accomplish this while also saving the
operator in heating costs.
• Thermally insulate the exterior of the outside air duct.
Step 4: Exhaust Air
The room should have a slight negative pressure.
ASHRAE recommends 0.05 to 0.15 inches of water
column. A good rule of thumb is to exhaust 110% of
the outdoor air CFM. A well located exhaust fan can
significantly improve the air quality in the space. If the
space has a spa or whirlpool, the exhaust air intake grille
should be located directly above it. This source captures
and extracts the most contaminant-laden air before it
can diffuse into the space and negatively impact the
room air quality.
• The exhaust fan can be installed remotely or within
the Seresco unit.
• Energy recovery from the energy rich exhaust air to
outdoor air should be considered.
Step 5: Load Calculations
The Natatorium needs to be heated, cooled and
dehumidified. Accurate calculations need to be carried
out to establish the requirements to accomplish each.
• Latent load (Pool evaporation, Outdoor Air (summer)
and Spectators)
• Building envelope sensible cooling load that includes
Outdoor Air.
• Building envelope heating load that includes
Outdoor Air.
A majority of designers prefer to place the space heating
coil inside the dehumidifier. The coils in a Seresco unit
are fully coated and suitable for a pool environment.
Seresco offers a full range of unit mounted control valves
as well.
Care must be taken when considering gas heating.
If chlorine from the natatorium is allowed to mix with
combustion gases, hydrochloric acid (HCl) forms and
is very corrosive. All Seresco’s gas heat options have
been engineered so that they are fully protected from
this ever happening.
Step 6: Condensation
and Vapor Migration
Establish the space dew point temperature based on
the owners desired space conditions. Once done, the
designer must identify all potential condensation spots
in the building. A typical pool design of 82°F 50-60% RH
has a peak dew point of 67°F. Therefore, any surface
with a temperature below 67°F will condense moisture.
A vapor retarder is a material that restricts the rate of
water vapor diffusion through the ceilings and walls of
a building when below dew point temperature occurs.
Failure to install the vapor retarder in the proper location
will result in condensation within the structure and lead
to tragic structural failure. Always ensure the vapor
retarder is sealed at all the seams.
• The Vapor retarder must be on the warm side of the
dew point temperature in all walls, ceilings and floors.
• All exterior windows, doors and skylights must be
fully blanketed with warm supply air. 3-5 CFM/ft² is
recommended.
Step 7: Energy & LEEDs
Considerations
The energy consumption and performance implications
of the building type and operating conditions must be
discussed with the owner.
Operating conditions
Operating conditions have a tremendous impact on
operating costs. It is critical that the owner understand
that at the same water temperature a pool in a room at
78°F 50% RH will evaporate almost 35% more than that
exact same pool in an 85°F 50% RH room. The pool
room should be kept as warm as possible but still be
comfortable to the patrons. Reduced evaporation in turn
reduces the dehumidifier size and runtime as well as
reduces the pool water heating requirement.
Heat recovery pool water heating
The dehumidifier’s pool water heating option should
be considered. It is site recovered energy and has a
very attractive payback period. This process has an
impressive COP of close to 8! The use of the pool
water heating option also satisfies ASHRAE Energy
Standard 90.1.
If it is chosen ensure that the pool water circuit
is designed to allow water to be delivered to the
unit reliably.
• Provide a separate circulating pump.
• Use the controls provided by the Seresco unit to
control the auxiliary water heater operation.
• Install the auxiliary pool water heater downstream of
the dehumidifier for backup heating.
• Ensure the pool water chemicals are introduced
downstream of the unit, auxiliary heaters and pumps.