INSTALLATION
EFFECT OF INSTALLATION ON PERFORMANCE
Any installation with inlet or discharge configurations that deviate from these recommendations may result in reduced fan
performance. Restricted or unstable flow at the fan inlet can cause pre-rotation of incoming air or even loading of the fan
prop yielding large system losses and increased sound levels. Free discharge or turbulent flow in the discharge ductwork
will also result in system effect losses.
The most common inlet and discharge conditions which affect fan performance are:
INLET DUCT TURNS
Installation of a duct turn or elbow too close to the fan inlet
reduces fan performance because air is loaded unevenly into
the fan prop. To achieve full fan performance there should
be at least one to two fan prop diameters between the turn
or elbow and the fan inlet.
DISCHARGE DUCT TURNS
Fan performance is reduced when duct turns are made
immediately off the fan discharge. To achieve cataloged
fan performance, there should be at least one equivalent
duct diameter of straight ductwork between the fan
discharge and any duct turns.
Motor at 3 or 9 o’clock position
TBIRU Installation
Curb Mounted
Good
Poor
Length of Straight Duct
1 Fan
Wheel
Dia.
Turning
Vanes
Good
Poor
Horizontal Ceiling Hung
Vertical Ceiling Hung
C
B
Optional
Mounting
Rails
D
C
Optional
Mounting
Rails
A
B
ROOF
CURB
CURB
CAP
TYPICAL INSTALLATIONS
Following are typical mounting installations for models TBI (horizontal or vertical mounting) and TBIRU (roof upblast).
Diagrams show dimensions for ceiling hung installations, the dimensions for floor or base mount installations are mirror
images of these. For TBI's with motor in the 3 or 9 o'clock position or vertical installations, additional mounting rails are
recommended. Mounting rail dimensions are shown for field fabrication.
Mounting Hole Locations
Fan B
Roof
Size
A
Level 3 Level 4
C
D
Opening
(TBIRU)
24
21
3
/
4
18
3
/
8
23
3
/
8
33
33
3
/
4
26
1
/
2
x 26
1
/
2
30
26
1
/
4
19
3
/
8
28
3
/
8
37
38
3
/
4
32
1
/
2
x 32
1
/
2
36
30
1
/
2
23
1
/
8
28
1
/
8
44
47
38
1
/
2
x 38
1
/
2
42
34
3
/
4
24
1
/
8
33
1
/
8
50
51
1
/
4
44
1
/
2
x 44
1
/
2
48
42
27
1
/
8
18
1
/
8
56
61
50
1
/
2
x 50
1
/
2
54
46
3
/
4
31
5
/
8
42
1
/
8
62
65
1
/
2
56
1
/
2
x 56
1
/
2
Unit Level Identification - Refer to fan name plate
Example:
TBI-3L42 (level 3)
TBI-4H30 (level 4)
