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7
Model VSU Make-Up Air
®
Burner/Blower Section
Use a crane and a spreader bar hooked to the factory
lifting lugs (shown below) to lift and center the unit onto
the filter stand section. The sections should be caulked
together.
Install Ductwork
This table shows the duct sizes and straight lengths
recommended for optimal performance (AMCA
Publication 201-90). Using duct sizes less than
recommended will affect fan performance. Good
duct installation practices should be followed for the
remaining ductwork.
Recommended Supply Ductwork Sizes
VSU
Blower Size
Duct Size
(in.)
Straight Duct Length
(in.)
108 10x13 32
109 14x13 38
110 16x14 42
112 18x16 48
115 19x16 49
118 24x22 64
120 28x28 79
218 68x24 114
220 68x26 118
225 104x37 175
230 104x37 203
Installation
Concrete Slab Dimensions
Housing Size A B C D E
20 64 64 42 40 40
30 77 76 42 52 53
40 78 135 42 54 111
50 87 180 42 63 153
All dimensions are shown in inches.
Building Wall
A
B
C
Concrete Slab
Approx. Stand Feet Locations
Required with service
platform only
12
E
D
12
Unit Control Side
Concrete Slab and Unit Footprint
Concrete Slab
The first step in unit installation is to pour a concrete
slab capable of holding the unit weight as a base. The
slab should have a proper gravel drainage bed.
Service and Access Clearance
The slab should be positioned to allow 3 feet of
clearance on the control end of the unit and 2 feet of
clearance on the other three sides. Housing size 50
requires 3 feet of clearance on both ends because of
filters access. Note that the concrete forms a 1 foot
wide apron on all four sides of the unit unless a 42 in.
extension is added to the control end of the unit.
NOTE
If optional service platform is included, a minimum of
42 inches must be added to Dimension B.
Clearance to Combustibles
Floor Top Sides Ends
Insulated/
Units
0 in.
(0 mm)
0 in.
(0 mm)
0 in.
(0 mm)
0 in.
(0 mm)
Non Insulated
Units
0 in.
(0 mm)
6 in.
(152.4 mm)
6 in.
(152.4 mm)
6 in.
(152.4 mm)
Clearance to combustibles is defined as the minimum distance required
between the heater and adjacent combustible surfaces to ensure the
adjacent surface’s temperature does not exceed 90 degrees above the
ambient temperature.
Spreader Bar