44
RT-SVX092A-EN
Note: No minimum clearance is required from duct to
combustible surfaces.
Roof Curb
Downflow
The roof curbs for these units consists of a full perimeter
enclosure to support the unit just inside of the unit base rail.
The C.0 cabinet units contain a support base alignment rail
and will extend past the end of the roof curb.
Before installing the roof curb, verify:
• It is the correct curb for the unit.
• Necessary gaskets and hardware are available.
• Confirm required clearance for installation and
operation.
• The curb should be level and square. The top surface
of the curb must be level in order to confirm an
adequate curb to unit seal.
WARNING
Combustible Materials!
Failure to maintain proper clearance between the unit
and combustible materials could cause a fire which
could result in death, serious injury, or property
damage.
Refer to unit nameplate and installation instructions
for proper clearances.
Verify that appropriate materials were used in the
construction of roof and ductwork. Combustible materials
should not be used in the construction of ductwork or roof
curb that is in close proximity to heater elements or any hot
surface. Any combustible material on the inside of the unit
base should be removed and replaced with appropriate
material.
Step-by-step curb assembly and installation instructions
ship with each accessory roof curb kit. Follow the
instructions carefully to confirm proper fit-up when the unit
is set into place.
Note: To verify proper condensate flow during operation,
the unit (and curb) must be 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
installation instructions. Curb ductwork must be fabricated
and installed by the installing contractor before the unit is
set into place.
Important: 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.
Note: C.0 units can be installed on B.0 (50 in. x 84 in.) roof
curbs with the use of factory-installed base
alignment brackets. These brackets create a 10-inch
overhang on the front of the unit. See for installation
on the B.0 (50 in. x 84 in.) curb and for installation
on the C.0 (60 in. x 84 in.) curb.
Figure 46. View for base to roof curb alignment on
C.0 cabinet on a 50 in. x 84 in. roof curb
Figure 47. View for base to roof curb alignment on
C.0 cabinet on a 60-in. x 84-in. roof curb
If a curb accessory kit is not used:
• The ductwork can be attached directly to the factory-
provided flanges around the unit supply and return air
openings. Use flexible duct connections at the unit.
• For built up curbs supplied by others, gaskets must be
installed around the curb perimeter flange and the
supply and return air opening flanges.
Installation
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