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Inlet Spin
- Inlet spin is a frequent cause of reduced fan
3/4 to
performance. The change in fan performance is a function
one fan
wheel
diameter
of the intensity of spin and not easily defined. The best
solution is proper duct design and airflow patterns.
Turning vanes reduce the effects of inlet spin.
3/4 to
one fan
wheel
Ducted Outlet Installations
diameter
Discharge Duct Turns
always be in the direction of the fan rotation.
Fan performance is reduced when duct turns are made immediately off the
FAN BYPASS
fan discharge. To achieve cataloged fan performance there should be at
.75 NPT
3/4 to one
AIR PLENUM
fan
least three equivalent duct diameters of straight ductwork between the fan
inlet
diameter
discharge and any duct turns.
ROOF
CURB
*
14.000
Non-Ducted Installations
3/4 to one
Inlet Clearance
3/4 to one
fan
fan
inlet
wheel
open inlet too close to a wall or bulkhead will cause
diameter
diameter
SUBFLOOR
reduced fan performance. It is desirable to have
a minimum of three-fourths of a wheel diameter
RECOMMENDED DRAIN TRAP DESIGN
between the fan inlet and the wall.
(TRAP BY OTHERS)
NEGATIVE PRESSURE TRAP
Note: A conservation method of trap design is to set
3/4 to one
fan
N = TSP and P = TSP (TSP = Total Static Pressure)
wheel
diameter
Single Fan Installation
Free Discharge
H
H/2
in a reduction in fan performance. The effect of discharge static
3/4 to one
regain is not realized.
fan
wheel
FAN OFF
diameter
N = Negative fan pressure (inches W.C.)
Fan Drainage Piping and Trap Detail
H = N - 0.5 inches minimum
Fans may have been supplied with an optional drain. Drains are located at the underside of the scroll housing.
The drain may need to be connected to a drainage system to ensure proper disposal of any water or condensate
that may occur.
RECOMMENDED DRAIN TRAP DESIGN
• Drain connections with a plug are 1 inch (25.4 mm) MNPT.
(TRAP BY OTHERS)
• Installed piping to have a downward angle to allow for drainage.
• Fill traps to recommended level before start-up.
POSITIVE PRESSURE TRAP
Three fan wheel diameters
Note: A conservative method of trap design is to set N = total static pressure.
NOTE: A conservative method of trap design is to set
N = Total Static Pressure and P = Total Static Pressure
Positive Pressure Trap
Connect
this end
to fan drain.
H/2
FAN OFF
1 Fan
Wheel
N = Negative fan pressure (inches W.C.)
Diameter
H = N - 0.5 inches minimum
Turning
Vanes
®
GOOD
3/4 to
One fan
one fan
diameter
wheel
diameter
3/4 to
One fan
one fan
diameter
wheel
diameter
- Duct turns located near the fan discharge should
ENERGY RECOVERY
PLENUM
3/4 to one
fan
inlet
diameter
ROOF
CURB
3/4 to one
- Installation of a fan with an
3/4 to one
fan
One fan
inlet
diameter
wheel
diameter
diameter
SUBFLOOR
3/4 to one
fan
wheel
diameter
1.25 inch minimum
N
- Free or abrupt discharge into a plenum results
H/2
FAN ON
POOR
POOR
N
H
H/2
FAN ON
POOR
3/4 to
one fan
wheel
diameter
1.25 NPT
NOTE: INSULATION OR OTHER MEANS
*
14.750
OF FREEZE PROTECTION MAY BE
REQUIRED IN CERTAIN CLIMATES
fan
1.2
1.0
(by others)
0.8
1.2
0.6
1.0
0.4
0.8
Three fan wheel diameters
0.2
0.6
0.4
0.0
Check local codes for proper disposal of drain water
0
5
which has been in contact with the exhaust air.
1.25 inch
GOOD
0.2
minimum
Fans used for grease exhaust need to be equipped
with a separate grease collector.
0.0
1.2
0
Series
1.0
100
0.8
300
0.6
500
* 1 inch (25.4 mm) non-threaded drain hole
0.4
0.2
POOR
POOR
One fan
diameter
Turning
*BASED ON STANDARD
Vanes
VEKTOR ERS CURB HEIGHTS
POOR
POOR
3/4 to one
3/4 to one
Three fan wheel diameters
fan
inlet
inlet
diameter
diameter
GOOD
Three fan wheel diameters
GOOD
POOR
SYSTEM EFFECT FACTORS CURVES
DRAWN BY
DATE
P.O.BOX 410 SCHOFIELD, WISCONSIN 54476-0410
06/29/2009
Length of Straight Duct
SUPERSEDES
TITLE
SCALE
ERS DRAIN SUBMITTAL
CAD DRAWING NO.
SYSTEM EFFECT FACTORS CURVES
GOOD
10
15
20
25
POOR
FPM X 100
OUTLET VELOCITY
SYSTEM EFFECT FACTORS CURVES
5
10
15
20
25
Drain Options
FPM X 100
Drain only *
OUTLET VELOCITY
No drain
Drain with plug
No drain
Drain with plug
Universal Single Width Fans
GOOD
GOOD
3/4 to
one fan
wheel
diameter
GOOD
fan
POOR
ECO
FAUST
ENG. REF.
VK-ERS
1/8
B
30
35
40
45
30
35
40
45
7
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
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