Direct Gas Make-Up Air
8
Metal Cover
Equipment
Support
Roof Curb
Curb and Equipment Support
Leg Supports
Unit Profile and Leg Support
2. Install Combination Curb Adaptor
Install combination curb adaptor over curb, fasten
adapter to curb using appropriate methods. Locate
extension so the tall louvered side is over the exhaust
opening, as shown in illustration. Caulk vented exhaust
extension to combination curb adaptor. Fasten
extension to curb adaptor using appropriate methods
(field-provided).
The installer is responsible for determining appropriate
support and fastening methods to ensure compliance
with all applicable codes.
3. Install Ductwork
Follow good duct practices for all ductwork. Install
ductwork in accordance with SMACNA and AMCA
guidelines, NFPA 96 and local codes. Reference
Installation, Duct Sizes
section in this Installation,
Operation, and Maintenance Manual for proper duct
sizes.
The use of a duct adapter is recommended on a
downblast (DB) arrangement to align the ductwork with
the supply unit. The duct adapter is only a guide and is
not to be used as a support for the ductwork.
Exhaust
Supply
1 inch
Inside Flange
Combination Extension
Supply
Ductwork
by Others
Exhaust
Ductwork
by Others
Ductwork
Installation
4. Apply Sealant
Apply an appropriate sealant around the perimeter of
the curb and duct to isolate unit vibration and prevent
water penetration.
Supply Duct with
Duct Adapter Installed
Exhaust Duct Installed
Sealant
Sealing Ductwork
Outdoor Unit Mounting
Combination Curb
1. Install Curb and Equipment/Leg Support(s)
Position curb and equipment/leg support(s) on the roof
(reference the unit submittal for placement in relation
to the unit). Verify that unit supports are level, shim
if necessary. Attach curb to roof and flash into place
using appropriate methods. Attach the equipment/
leg support(s) to the roof, remove metal cover, flash to
wooden nailer and reinstall cover.