McQuay OAH Installation Manual
Installation and Maintenance Manual IM770
Roof Curb for SkylineTM Outdoor Air Handlers
Group: Applied Air
Part Number: IM770
Date: April 2003
© 2003 McQuay International
IM 770 Page 1
Table of Contents
General Description .............................................................3
Curb-Ready Air Handler ..................................................... 3
Curbing Kit ..........................................................................3
Curbing Kit Assembly......................................................... 6
Roof Curbs with a Vestibule Assembly................................6
Prepare The Unit For Installation On Curb.......................... 6
Install Unit on Roof Curb .....................................................7
Installation of Piping and Wiring......................................... 8
Page 2 IM 770
General Description
Curb-Ready Air Handler
The Skyline™ outdoor air handler unit can be equipped with
a base assembly that provides a mechanical fit and seal to the
building's Island Roof Curbing. Skyline outdoor air handlers
must be ordered from the factory with a curb-ready base in
order to mount units on a roof curb. The curb-ready base is
not available for field application to the Air Handler.
Figure 1 shows various base rail options for Skyline outdoor air
handlers. Units that do not have base rails and units with standard base rails must NOT be used with open curbs of any type.
Figure 1. Base Rail Options
Unit with
Curb-ready Base Rail
Nests Over Curb
Roof Curb
followed when applying this roof curb and any curbs that
may be field designed.
The curbing must support the air handler uniform ly to keep
the cabinet square and true. Uneven curbing support can
cause distortion of the cabinet and the door openings.
Unit location
The structural engineer should be involved to verify that the
roof has adequate strength and ability to minimize deflection.
Extreme caution should be taken when using a wooden roof
structure. Units should also be located away from building flue
stacks or exhaust ventilators to prevent possible entry of contaminated air through the outside air intake. Sufficient space
should also be allowed around the unit for service clearance.
Locating the unit away from occupied spaces and over utility
areas, corridors, and auxiliary spaces will help reduce the
transmission of sound and vibration to occupied spaces. A
concrete deck or pad is recommended when the unit is located
over an occupied space where good acoustics are essential.
See the installation inst ructio ns (IM77 7) for more d etails on
locating units.
Curbing Kit
The Skyline air handler roof curb kit is shipped unassembled
and requires field assembly and attachment to the field
designed building structural support. The building structural
supports for curb mounted units must be approved by qualified individuals. It is important to follow all building codes
and roofing standards.
Unit without
Base Rail
Do not place on open curbs
Unit with
Non-curb-ready
Base Rail
Do not place on open curbs
The information provided in these instructions describes the
curb kits that are ordered and provided with the Skyline outdoor air handler. The curb kits are intended to be installed as
described and are not intended to be modified or used in conjunction with other curb mounting features or apparatus.
The dimensional and support requirements are outlined to
provide a basis for field designed and applied roof curbs. It
is important that the weight and strength factors be carefully
The unit dimensions, weights and compon ent d etails are provided within the submittal documents and are unique for
each unit. The submittal documents also indicate the functional components within the air handler. While the total
weight of each unit section is shown in the submittal documents, the locations of coils, motors and fans can cause part
of the load to be concentrated in one area of an air handler
section. Appropriate safety factors should be used to account
for the weight distribution in determining structural load.
Allowance must be made for routing the air ducts through the
roof curb. Refer to the submittal data for each unit for the
proper dimensions of duct openings prior to installing ductwork. Figure 2 on page 4 shows a typical submittal drawing
for a curb-ready Skyline air handler. The unit submittal drawing illustrates the roof curb layout of the unit. The drawing
shows the outline of the air handler unit, the outside dimension of the curbing top flange and the inside dimension of the
curbing. The Skyline units may have piping vestibule sections included as part of the unit selection and the roof curb
will also have a vestibule curbing section attached to it. The
submittal drawing shows the location and dimensions for the
piping vestibule.
The submittal drawings also show the locations and dimensions of the air duct passages in the roof curb. The roof curb
may be ordered as a unit option or it can be field supplied.
View A shows a side view of the cabinet and View B shows
an end view. If the unit is ducted in the middle (not adjacent
to the curb), no allowances are required (View C).
IM 770 Page 3
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