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Ductwork
Duct Systems - General
The duct system should be constructed of standard galva-
nized sheet metal, such as would be used for a typical residen-
tial heating system. All joints should be sealed with an ap-
proved duct sealant to ensure there are no leaks in the system.
A duct system capable of supplying the required air flow is
of utmost importance. Maritime Geothermal Ltd. recommends
that the static pressure be kept below 0.2 inches of water total.
It is
VERY IMPORTANT
trunks and the return trunks be made with
acts like a fluid and, just like water, pressure drop is increased
when air is forced to change direction rapidly around a sharp or
irregular corner.
It is recommended that flexible collars be used to connect
the main trunks to the heat pump. This helps prevent any vibra-
tions from travelling down the ductwork.
The first 5-10 feet of the main supply trunks may be insu-
lated with acoustical duct insulation to further inhibit any noise
from the unit from travelling down the ductwork.
Supply Duct System
The care and attention devoted to setting up the air
distribution system can make or break any indoor pool
conditioning system. Important factors to consider are:
1)
Sufficient air must be moved within the pool enclosure to
satisfy the requirements of both the occupants of the room
and the pool conditioner, with maximum flow directed over
the outside windows and doors and minimum flow directly
over the exposed surface of the pool itself.
2)
To prevent air stagnation and stratification the system must
provide at least 4 to 8 room air changes per hour.
3)
The PC unit supply air ductwork must be adequately sized
to handle 1200 to 2400 cfm of air (depending on the model
size) with no more than 0.20" H
pressure. See following table for a duct sizing guide that
can be used to select adequate duct sizes.
4)
An in-floor duct system is usually the most effective method
of supplying air to the room (see following diagram).
Distribution of the conditioned air will be most effective if the
air is released from the floor and allowed to rise upwards
over the glass surfaces. It is important to try and blanket the
entire surface of glass windows and metal doors with a film
of dry air from the pool conditioner to prevent accumulation
of condensation at the corners or bottom of the glass. If a
ceiling ducted system is chosen, then the supply air should
be of sufficient velocity to ensure that air flows over the
glass all the way down to the bottom of the window.
5)
Long, narrow supply grills should be placed under all glass
areas exposed to outside temperatures for optimum
operation.
6)
Additional care should be taken to ensure that airflow is not
directed across the pool surface since moisture loss from
the pool water will be greatly increased under these
conditions.
7)
If a floor distribution system is not possible then ceiling
ducts should be positioned to blow down over the exposed
glassed areas of the room perimeter. It may be necessary
to increase the airflow using the PC App to accomplish the
more difficult task of forcing the air exiting the supply ducts
down over the glass.
ISSUE 03: 1-Oct-2021
that all turns in both the supply
RADII. Air
TURNING
O of external static
2
Return Duct System
The air inlet of the return duct system should ideally be
placed 10 to 15 ft above the pool level. Placing this duct inlet in
an elevated position will ensure that air travels in an upward
fashion if it is introduced from the floor. An airflow pattern which
causes minimum airflow across the pool surface should be used
to minimize evaporation from the pool surface. Large volumes
of air travelling near the pool surface can also cause swimmers
to feel cold whenever they emerge from the water.
Plenum Heater
As mentioned in previous sections, it is recommended that
a plenum heater be installed to provide pool room air auxiliary
heat.
The plenum heater should be mounted in the supply duct
in a manner that allows all or most of the airflow to pass through
it to prevent any hot spots in the heater elements. If the ele-
ments overheat due to experiencing low airflow, they will shut
down on thermal overload controls in the plenum heater, and
sporadic operation resulting in low heat output will occur.
The plenum heater should be placed downstream of the
flex collar as shown in diagram 002297PDG, or at least 12"
away from the flex collar if placed upstream. Duct insulation
should not be placed within 12" of the heater elements.
Page 19
002291MAN-03
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