Utility and Centrifugal Fans
11
®
Ducted Outlet Installations
Discharge Duct Turns
- Duct turns located near
the fan discharge should always be in the direction of
the fan rotation.
Fan performance is reduced when duct turns
are made immediately off the fan
discharge. To achieve cataloged fan
performance there should be at least
three equivalent
duct diameters of
straight ductwork
between the fan
discharge and
any duct turns.
Non-Ducted Installations
Inlet Clearance
- Installation of a fan with an
open inlet too close to a wall or bulkhead will cause
reduced fan performance. It is desirable to have
a minimum of three-fourths of a wheel diameter
between the fan inlet and the wall.
Free Discharge
- Free or abrupt discharge into a
plenum results in a reduction in fan performance. The
effect of discharge static regain is not realized.
R
o
ta
tion
R
o
ta
tion
POOR
Length of Straight Duct
GOOD
3/4 to one
fan
wheel
diameter
Single Fan Installation
Fan Drainage Piping and Trap Detail
(by others)
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.
• Drain connections with a plug are 1.0 inch
(25.4 mm)
MNPT
• Installed piping to have a downward angle to allow
for drainage
• Fill traps to recommended level before start-up
Note: A conservative method of trap design is to set
N = total static pressure.
Check local codes for proper disposal of drain water
which has been in contact with the exhaust air.
Fans used for grease exhaust need to be equipped
with a separate grease collector.
Positive Pressure Trap
N = Negative fan pressure (inches W.C.)
H = N - 0.5 inches minimum
H/2
H/2
H
1.25 inch
minimum
N
FAN ON
FAN OFF
Connect
this end
to fan drain.
Drain Options
USFD-100
Drain only*
USF-200
None
Drain only*
With plug
USF-300
None
With plug
USF-400
None
With plug
CSW
None
With plug
*1.0 inch
(25.4 mm)
non-threaded drain hole
