I-RPB (04-21) 131782-A, Page 6
5.3.1 Curb Cap Base
Outdoor systems are equipped with a load bearing curb cap which forms an integral
part of the unit. This curb cap has welded joints and has a skirt that ts over a roof curb
to provide a weatherproof installation. Four holes are provided at the curb cap corners
for lifting the unit. These holes do not interfere with unit weatherproong. The curb
cap is not designed to be placed directly on the roof surface. The system may be
mounted on an optional roof curb purchased with the unit, a eld-supplied roof curb, or
eld-supplied supports. If the system has a downturn plenum and/or a bottom return
air opening, a roof curb is recommended to provide a weatherproof installation as well
as more workable clearances for ductwork.
5.3 Mounting Base
and Methods
5.3.2 Mounting
on Field-Supplied
Supports (without a
roof curb)
Prior to installation, be sure that the method of support is in agreement with all local
building codes and is suited to the climate. If considering this type of installation in
snow areas, it is recommended that the 4x4 wooden rails underneath the system be
on cross-support structure at least 12" higher than the roof surface (see support loca-
tions in FIGURE 2B).
Whether the supports are being mounted directly on the roof or being placed "up" on
additional structure, the horizontal length of the system should be supported by two
4x4 treated wooden rails. Cut the rails to the appropriate length (dimension A) in FIG-
URE 2A. NOTE: Although dimensions are included for units with a downturn plenum
cabinet, it is strongly recommended that a full roof curb be used on an installation with
a downturn plenum cabinet and/or a bottom return air duct.
Space the 4 × 4 wooden rails (see dimension B, FIGURE 2A) so that the curb cap skirt
will t over the edge of the boards with the rails setting inside the horizontal length of
the curb cap.
If the rails are being laid directly on the roof, position them as shown in FIGURE 2A.
Set the system on the rails, leaving the ends underneath open for ventilation.
If the treated wooden rails are not being placed directly on the roof surface, cross-
supports should be placed underneath the rails at the ends of the unit and at all cabinet
joints: between the blower cabinet and the furnace section and between the furnace
and the optional downturn plenum (see FIGURE 2B).
The eld-supplied, weather-resistant cross-support structure must be adequate for the
weight of the system. Cross-supports should run the entire width of the system sup-
porting the 4x4 wooden rails at the recommended locations (see FIGURE 2B).
Blower
Cabinet
Furnace
Section
Field
Supplied
Duct
4x4 Treated
Lumber
= Cross Support Locations
Field
Supplied
Duct
FIGURE 2B - Cross-Support Locations
Whether using an optional roof curb available with the system or a eld-supplied curb,
the curb must be secure, square and level. The top surface of the roof curb must be
caulked with 1/4" × 1-1/4" sealant tape or two 1/4" beads of suitable sealant. The unit
must be sealed to the curb to prevent water leakage into the curb area due to wind
blown rain and capillary action. Except for the curb assembly details which are specic
to the optional roof curb available with the system, the information and requirements
FIGURE 2A - Mounting Support Dimensions (inches/mm)
Unit
Size
Standard Heater
and Blower
Package
With Factory-Installed
Downturn Plenum
Cabinet (Option AQ)
All
A A B
125 60-5/8" 84-9/16" 24-5/16"
150, 175 60-5/8" 84-9/16" 29-13/16"
200, 225 60-5/8" 84-9/16" 35-5/16"
250, 300 60-5/8" 84-9/16" 43-9/16"
350 60-5/8" 84-9/16" 49-1/16"
400 60-5/8" 84-9/16" 54-1/2"
125 1540mm 2148mm 618mm
150, 175 1540mm 2148mm 757mm
200, 225 1540mm 2148mm 897mm
250, 300 1540mm 2148mm 1106mm
350 1540mm 2148mm 1246mm
400 1540mm 2148mm 1384mm
5.3.3 Mounting on a
Roof Curb
5.0 Mounting
(cont'd)
To Next Page
Loading...
Need help?
General
