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4
B
C
L
C*
Rectangular
Curb
Footprint
C
L
C
L
A
A/2
A
Roof
Opening
A/2
C*
C*
*C- Determine equal dimension for these 3 locations
Sealant
Ductwork
Duct Adaptor
Supply
Ductwork
by Others
Step 1 Roof Opening
Determine the center of the supply duct roof
opening. The chart below shows the maximum
recommended roof opening dimensions. These
sizes can be smaller based on codes and
ductwork sizes.
A - Max Roof Open. Sq. 47"
Supply Duct C
L
to
B - 88
1
/2"
Equip. Support C
L
Before beginning this installation:
Make sure that there is room to access the unit from all sides.
Make sure inlet of unit is located well away from any exhaust fans.
Step 3 Install Ductwork
The chart shows at left shows the duct
sizes and straight lengths recommended
for optimal performance (AMCA Publication
201-90). Using duct sizes less then
recommended lengths will affect fan
performance. Good duct installation
practices should be followed for the
remaining ductwork. The use of a duct
adapter with the supply duct is strongly
recommended to properly align the
ductwork with the supply fan discharge.
The duct adaptor is only a guide and is not
intended to be used as support for the
ductwork.
Step 4 Apply Sealant
Before installing unit apply a sealant or a
gasket around the perimeter of the supply
duct adaptor to isolate the fan and
minimize vibration.
For Installations using rectangular curb
Recommended Supply
Ductwork Sizes
Straight
Duct Duct
Size Length
16 x 16 54"
Installation Instructions for:
NV-45 w/Downblast Discharge
Step 2 Install Roof Curb and
Equipment Support
For rectangular curbs, center curb on 3 sides of roof opening, as shown in above installation diagram, by
determining C dimension (varies per unit/curb size). For either installation, level the curb and shim if necessary.
Attach curb to roof and flash in place.
If equipment support is needed, refer to chart in step 1 for dimensional location based on NV unit size. Attach to
roof in the same manner as the curb. Remove metal cover, flash to wooden nailer, and reinstall cover.