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Installation
Roof Curb and Ductwork
The roof curbs consist of two main components: a pedestal
to support the unit condenser section and a "full perimeter"
enclosure to support the unit's air handler section.
Before installing any roof curb, verify the following:
•
It is the correct curb for the unit.
•
It includes the necessary gaskets and hardware.
•
The purposed installation location provides the required
clearance for proper operation.
•
The curb is level and square — the top surface of the
curb must be true to assure an adequate curb-to-unit
seal.
Step-by-step curb assembly and installation instructions
ship with each Trane accessory roof curb kit. Follow the
instructions carefully to assure proper fit-up when the unit is
set into place.
Note: To assure proper condensate flow during operation,
the unit (and curb) must be as level as possible. The
maximum slope allowable for rooftop unit
applicationsexcluding Steam Heat Units, is 4" end-
to-end and 2" side-to-side. Units with steam coils
must be set level!
If the unit is elevated, a field constructed catwalk around
the unit is strongly recommended to provide easy access
for unit maintenance and service. Recommendations for
installing the Supply Air and Return Air ductwork joining the
roof curb are included in the curb instruction booklet. Curb
ductwork must be fabricated and installed by the installing
contractor before the unit is set into place.
Note: For sound consideration, cut only the holes in the
roof deck for the ductwork penetrations. Do not cut
out the entire roof deck within the curb perimeter.
Pitch Pocket Location
The location of the main supply power entry is located at
the bottom right-hand corner of the control panel. illustrates
the location for the electrical entrance through the base in
order to enter the control panel. If the power supply conduit
penetrates the building roof beneath this opening, it is
recommended that a pitch pocket be installed before the
unit is placed onto the roof curb.
The center line dimensions shown in the illustration below
indicates the center line of the electrical access hole in the
RT-SVX073A-EN
unit base when it is positioned on the curb, ±3/8 inch. The
actual diameter of the hole in the roof should be at least 1/2
inch larger than the diameter of the conduit penetrating the
roof. This will allow for the clearance variable between the
roof curb rail and the unit base rail illustrated in
26.
The pitch pocket dimensions listed are recommended to
enhance the application of roofing pitch after the unit is set
into place. The pitch pocket may need to be shifted as
illustrated to prevent interference with the curb pedestal.
Figure 4. Solid flow baffle wall installation for non-
Trane roof curbs
Return Fan
Roof Curb
Flow Baffle
Return Airflow
If a Trane Curb Accessory Kit is not used:
•
The ductwork can be attached directly to the unit
bottom, around the unit supply and return air openings.
Be sure to use flexible duct connections at the unit.
•
For "built-up" curbs supplied by others, gaskets must
be installed around the curb and the supply and return
air opening perimeters.
•
If a "built-up" curb is provided by others, it should NOT
be made of wood.
•
If a "built-up" curb is provided by others, keep in mind
that these commercial rooftop units do not have base
pans in the condenser section.
•
If this is a REPLACEMENT UNIT keep in mind that the
CURRENT DESIGN commercial rooftop units do not
have base pans in the condenser section.
Figure 5, p.
Return Airflow
Duct
25
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