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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
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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
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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).
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Figure 2. Typical submittal drawing and air duct allowances through the roof curb.
Opening X Y Z W (Width) H (Height)
A Duct 4.75 4.75 16.00 76.50 25.25
B Duct 190.00 4.75 16.00 76.50 25.25
Dimensions measured from
244.00
238.50
234.50
CC
78.00
23.25
B
0
5
.
2
7
AA
21.25
2.75 Typ
2.75 Typ
)
e
d
i
s
t
u
o
h
t
d
i
w
t
i
n
U
(
0
0
.
2
8
37.25
)
)
e
e
d
d
i
i
s
s
t
n
u
i
o
h
t
h
t
d
i
d
i
w
w
b
r
b
r
u
u
C
(
C
(
0
0
5
.
5
.
2
6
7
7
35.25
0
5
.
2
7
96.00
MPLE
2.75 Typ
A
S
148.00
View A – Side View of Ducted End
Note that the inside of the curbing is
4.75 inches from the side of the unit.
Outside Unit
Duct
Opening
.38
4.75
2.00
Max Duct
Clearance
Roof Opening
Into Building
Roof
18.00
(Unit length outside)
(Curb length outside)
(Curb length inside)
e
s
a
B
b
r
u
C
B
18.50
View B – End View of Ducted End
Note that the inside of the curbing is 4.75 inches
from the outside of the unit on both sides.
68.00
t
i
n
U
e
s
a
B
4.75
b
r
u
C
Roof
Duct
Opening
.38
2.00
Max. Duct
Clearance
Roof Opening
Into Building
.38
2.00
4.75
Unit Duct
Opening
Duct Opening
Max.Duct
Clearance
Roof Opening
Into Building
View C – Side View of Unit Ducted In Open Space of Roof Curb
The duct opening through the roof curb is the same as the unit
duct opening.
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Figure 3. Roof Curb Features.
39.25
96.00
238.50
234.50
78.00
25.25
CU140
CU146
18.00
CU237
18.50
CU232
CU152
CU162
CU156
70.00
CU122
72.50
21.25
23.25
B
B
2.002.00
CU122
A
72.50
72.50 (Curb width inside)
76.50 (Curb width outside)
35.25
41.25 92.00 78.00
CU137
CU140
CU132
150.00
(Curb length outside)
(Curb length inside)
A
(Total length outside)
Gasket Provided for
Field Installation
A
Figure 3 illustrates the features of the roof curb. Intermediate
support channels are provided for support of the supply and
return air ducts. If the curbing is field supplied, the duct supports can be provided in accordance with the installation
requirements.
Intermediate supports are provided in the curb assembly at all
points where the curb rails require two sections to b e joined.
For field provided roof curbs, it is recommended that intermediate supports be incorporated as appropriate for lateral
rigidity of the roof curbs.
B
Intermediate supports are also provided on roof curbs that are
over 107 inches wide. These supports are required at all
points where the roof curb sides are joined. Support is also
required at the entering and leaving edges of cooling coil sections and fan sections. These intermediate supports are
required on all wide unit curbs to provide support to the unit
across the open span of the curb.
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Curbing Kit Assembly
The weight of the unit is concentrated and supported at the
inside wall of the roof curb. The structural system of the
building and the interface with the curb must provide support
at the points of concentrated loads. See Figure 4.
Roof curbs with a vestibule as semb ly.
NOTE: The vestibule assembly channel, part number CU146
must be attached to the vestibule curb assembly before the
vestibule assembly is attached to the main roof curb. Use two
1/4 x 1/2 screws to attach the channel.
Figure 4. Weight of unit on roof curb.
Gasket
Wood 2" x 4"
Nailer Strip
Metal Flashing
(Not furnished)
Roof Seal Membrane
Weight
Structural
Support
(Not furnished)
Roof Insulation
(Not furnished)
Each curb kit contains a hardware package. The package
contains 3/8 -16 x 1" bolts and nuts for assemb ly of the curb.
Two 1/4 - 20 x 1/2" screws are included when the unit has a
vestibule. Rolls of gasket are included to cover the top surfaces of the curb and supports.
The hardware kit includes a layout and assembly drawing of
the curbing with a sketch of the assembly.
Compare the curb layout drawing to the submittal documents
for the air handler to confirm that the details match.
Figure 3 illustrates a typical layout drawing of the roof curb.
Note that each air handler will have a dedicated drawing that
corresponds with the features that are included in the unit.
The curbing parts should be laid out according to the assembly drawing. The drawing shows dimensions of the parts and
locations of intermediate cross members. The curb parts
have labels attached that correspond with th e locatio ns of the
parts. Parts that are identical have the same part numb ers.
End parts have number CU122 and center supports have
number CU140.
The vestibule assembly is then attached to the main roof curb
by sliding the rear vertical flange of the vestibule curb under
the lip of the main roof curb. Apply sealant and gasket material after the vestibule curb is in place. See Figure 5.
Figure 5. Install vestibule assembly on main roof curb.
1. Assemble Channel
CU146 to Vestibule
Curb Assembly using
1/4" x 1/2" Screws.
3. Apply sealant
and gasket after
2. Slide the rear
vertical flange of
the vestibule assembly
under the lip of the
main roof curb.
Main
Roof Curb
Vestibule Curb
Assembly is in place.
The side supports are shown with sequential numbers
CU137, CU 237 and so on for parts on one side of the drawing. Likewise, parts on the other side have sequential num-
Vestibule
Curb Assembly
bers CU 132, CU 232 in progression. The curb parts for the
vestibule are marked with labels CU 152, CU 156 and
CU162.
The dimensions for the locations of all parts are shown and
should be checked carefully for proper assembly order.
Assemble the curb with the 3/8 inch diameter bolts and nuts
that are provided. Always check the di mensions o f the curb
before final installation to the roof and building structure.
Also check to be sure the curb is square and level.
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Prepare The Unit For Installation On Curb
THE UNIT MUST BE LIFTED AS INDIVIDUAL SECTIONS ONLY. Some sections require removal of the lifting
bracket to allow mating of the adjacent section(s). See Figure
10 on page 8.
A length of "D" gasket is attached to each section. This gasket MUST be installed to the unit base section as shown in
Figure 6.
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Figure 6. Attaching "D" gasket.
" D " G a s k e t
IMPORTANT
The gasket is to be installed in an arc shape with
the ends lower than the center so that any moisture that may reach the gasket will be drained to
the outside of the unit.
A hardware package is included in each unit section that contains the bolts and nuts for fastening the unit sections
together. Be sure to locate the hardware before the unit is
placed over the open roof curb.
Fasten each section at both the bottom and the top using the
bolts and hardware before setting the next section in position. Refer to Figure 8 and Figure 9.
Figure 8. Fasten bottom of section.
Apply a bead of sealant to the complete perimeter of the mating surface that has the splice collar projecting from the
frame. Use the frame as a guide as illustrated in Figure 7.
Figure 7. Applying sealant.
5 / 1 6 " d i a m e t e r
b e a d c e n t e r e d
i n f a c e o f
c l e a r a n c e
U s e S p l i c e
J o i n t a s a
g u i d e
Install Unit On Roof Curb
Check to see that all lifting brackets are secure and that the
rigging cables and straps are clear of door handles or any
other appendages of the unit.
The units have two inch interlocking splice collars at each
mating face. Care must be used so that the flanges engage as
the unit sections are mounted together. The units must be set
tightly together during lifting as the curb gasket will grip the
unit base and make moving the unit difficult.
3 / 8 x 1 " B o l t a n d N u t
Figure 9. Fasten top of unit.
S l i d e S p l i c e C a p o n
a n d b e n d e n d s d o w n
5 / 1 6 - 1 8 B o l t
5 / 1 6 - 1 8 N u t
S p l i c e
P l a t e
IM 770 Page 7
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Units with vestibules must be handled so that the lifting
bracket can be removed after the unit is placed on the curbing. Remove the lifting bracket that projects inwa rd over t he
curbing. Save the self tapping bolts. When the adjacent section is placed in position, use self tapping bolts to secure the
bases together as illustrated in Figure 10.
Figure 10. Remove vestibule lifting bracket.
Complete cabinet by placing sealant over any areas that
appear to have remaining gaps. Install the cabinet top strips
as indicated in IM Bulletin 672 that is included with the air
handler.
Assemble and install all air hoods in accordance with the
instructions that are provided with hood.
Installation of Piping and Wiring
Be sure that all piping, wiring and control penetrations that
are made through the unit panels and floors are thoroughly
sealed on both the inside and outside of the cabinet.
NOTICE:
The base section of each cabinet has a drip pan
installed below every panel that drains to the outside
frame trough. Any holes cut through the bottom of
the unit must also penetrate the drip pan. If holes are
cut in the drip pan, they must be sealed to prevent
moisture leakage.
A single metal thickness pan is provided in the bottom of the
vestibule. The pan can be removed if necessary. If holes are
cut into the pan for piping passage, the holes must be sea led
to prevent moisture leakage.
R e m o v a b l e
L i f t i n g B r a c k e t
This document contains the most current product information as of this printing . For the most up-to-da te
product information, please go to www.mcquay.com.
13600 Industrial Park Boulevard, Minneapolis, MN 55441 USA · (800) 432-1342 · www.mcquay.com
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