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The following section contains basic application and installation
guidelines that must be considered as part of the detailed
analysis of any specific project.
General
Units are intended for use in normal heating, ventilating and
air conditioning applications and 100% outdoor air application.
Consult your local Daikin Sales Representative for applications
involving operation at abnormal temperatures, high altitudes,
non-cataloged voltages and for applications requiring modified
or special control sequences. Consult your local Daikin sales
representative for job specific unit selections that fall outside of
the range of the catalog.
Unit Location
The structural engineer must verify that the roof has adequate
strength and ability to minimize deflection. Locate the unit
fresh air intakes away from the building flue stacks or exhaust
ventilators to reduce possible reintroduction of contaminated
air to the system. Unit condenser coils should be located to
avoid contact with any heated exhaust air.
Service Clearances
Allow sufficient space around the unit for maintenance/service
clearance. Refer to
Figure 24 on page 27
clearances. Where code considerations, such as the NEC
require extended clearances, these take precedence. Provide
a roof walkway along sides of the unit for service and access
to controls and components. Consult your Daikin sales
representative if available clearances do not meet minimum
recommendations
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Operating Range
Daikin Rebel Applied rooftop systems are designed to operate
over an extensive operating range. However, for proper system
operation some limits do apply.
Most rooftop applications take advantage of the significant
energy savings provided by economizer operation. When
an economizer system is used, mechanical refrigeration
is not typically required below an ambient temperature of
50°F. Standard Rebel Applied refrigeration systems are
designed to operate in ambient temperatures down to 50°F.
For applications where economizers cannot be used, the
Rebel Applied is provided with a modulating condenser
fan head pressure control and low ambient condenser coil
control system for mechanical cooling operation in ambient
temperatures down to -10°F.
To help prevent moisture blow-off, design guidelines have been
established for cooling coil selection. Based on laboratory
testing, average coil face velocities should not exceed
600 ft./min. For applications outside of these limits, consult
your Daikin sales representative. Velocities exceeding these
limits not only present the potential for moisture carryover,
but also high face velocities generate high air pressure drops,
resulting in poor fan energy performance
In addition to maximum face velocity limitations, minimum
velocity guidelines must also be followed. In order to maintain
proper refrigeration performance, the minimum coil face
for recommended
velocity is 150 ft./min. When selecting a variable air volume
unit, it is necessary to design the system such that the
150 ft./min. limit is maintained at light load conditions.
29
Application Considerations
CAT 258 • REBEL APPLIED ROOFTOP
Application Considerations
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