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Installation Instructions for:
CURB MOUNTING*
NV-90 and NV-120
2. Locate and Cut Roof Opening
When locating unit, make sure there is room to access unit
from all sides. Make sure inlet of this unit is located well
away from exhaust fans.
Roof Opening for NV-120 and NV-90 = (A) 36" x (B) 36"
3. Install Curb
Located curb over roof opening with dimensions shown to
the right and fasten in place.
Check that diagonal dimensions are within
± 1/8" of each other and adjust as necessary. Shim as
required to level.
Roof Opening
Ductwork
by Others
Roof Curb
A
B
4. Install Ductwork
D
The following chart shows the duct sizes and straight
lengths recommended for optimal performance (AMCA
Publication 201-90). Using duct sizes less than
recommended lengths will affect fan performance. Good
C
duct installation practices should be followed for the
remaining ductwork.
*For installations using Greenheck's
optional roof curb.
1. Assemble Roof Curb
Curbs are shipped knockdown and require assembly
by others. Assembly instructions are also included
with curb.
Assemble curb sections as shown using hex bolts and
lock nuts supplied with curb.
Detail shown is typical for all four corners.
Roof Curb
5
40
/
8
Duct Locations:
A
B
C
3
NV-90
24
9
/
24
8
1
NV-120
26
9
/
26
2
9
1
4
/
2
1
24
/
4
Recommended
Roof Opening
(36"x36")
1
43
/
4
81
3
/
16
Straight
D
Duct Length
1
30
/
81
4
1
29
/
96
4
1
103
/
2
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