3
outside air damper is added, an inlet air screen
will also be present.
Each of these filters and screens will need to be periodically re-
placed or cleaned.
RETURN AIR FILTERS
Return air filters are disposable fiberglass media type. Access
to the filters is through the vertical panel to the right of the con-
trol box. Filters are situated on slide-out racks for easy inspec-
tion and repair. (See Fig. 1.)
To remove the filters:
1. Remove vertical filter access door.
2. Reach in and extract the filters from the filter rack.
3. Replace these filters as required with similar replacement
filters of same size. Observe the flow direction arrows on
the side of each filter frame.
4. Re-install filter access panel.
OUTSIDE AIR HOOD
Outside air hood inlet screens are permanent aluminum-mesh
type filters. Check these for cleanliness.
Remove the screens when cleaning is required. Clean by wash-
ing with hot low-pressure water and soft detergent and replace
all screens before restarting the unit. Observe the flow direc-
tion arrows on the side of each filter frame.
ECONOMIZER AND MANUAL OUTSIDE AIR SCREENS
This air screen is retained by spring clips under the top edge of
the hood. (See Fig. 3.)
Fig. 3 — Filter Installation
To remove the filter, remove screws in horizontal filter retain-
ers on leading edge of hood. Slide filters out. To re-install fil-
ters, slide clean or new filters into hood side retainers. Once
positioned, re-install horizontal filter retainer.
SUPPLY FAN (BLOWER) SECTION
Supply Fan Assembly
The supply fan system consists of two forward-curved centrif-
ugal blower wheels mounted on a solid blower shaft that is
supported by two greaseable pillow block concentric bearings.
A fixed-pitch driven (fan) pulley is attached to the fan shaft
and an adjustable-pitch driver pulley is mounted on the motor.
The pulleys are connected using a “V” type belt. (See Fig. 4.)
Fig. 4 — Belt Drive Motor Mounting
BELT
Check the belt condition and tension quarterly. Inspect the belt
for signs of cracking, fraying or glazing along the inside sur-
faces. Check belt tension by using a spring-force tool (such as
Browning’s “Belt Tension Checker” or equivalent tool); ten-
sion should be between 5 and 10 lbs with
5
/
8
-in. deflection
when measured at the centerline of the belt span. This point is
at the center of the belt when measuring the distance between
the motor shaft and the blower shaft.
NOTE: Without the spring-tension tool, place a straight edge
across the belt surface at the pulleys, then deflect the belt at mid-
span using one finger to a
1
/
2
-in. deflection.
Adjust the belt tension by loosening the four motor mounting
nuts and bolts where the motor bolts to the blower rail. There
are two jack bolts and nuts that are used to slide the motor plate
to either increase or decrease belt tension. There are locking
nuts on the jack bolts that need to be loosened at the motor
plate. Turn the jack bolts clockwise or counter clockwise until
the correct belt tension is achieved. Ensure the fan shaft and
motor shaft are parallel prior to tightening motor plate nuts.
(See Fig. 5.)
Fig. 5 — Adjusting Belt Tension
IMPORTANT: DO NOT OPERATE THE UNIT WITH-
OUT THESE FILTERS!
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal inju-
ry or death.
Before performing service or maintenance operations on
unit, LOCKOUT/TAGOUT the main power switch to unit.
Electrical shock and rotating equipment could cause severe
injury.
S
tep 1: Loo
s
en
motor bolt
s
S
tep 2: Loo
s
en j
a
ck bolt
lock n
u
t
s
S
tep
3
: Loo
s
en or tighten
j
a
ck bolt
s
u
ntil proper
belt ten
s
ion i
s
a
chieved
Summary of Contents for 50LC 14
Page 26: ...26 Fig 34 50LC 14 26 Control Wiring Diagram...
Page 27: ...27 Fig 35 50LC 14 26 RTU Open Control Wiring Diagram...
Page 28: ...28 Fig 36 50LC 14 20 208 230V 3 Phase Power Wiring Diagram...
Page 29: ...29 Fig 37 50LC 24 26 208 230V 3 Phase Power Wiring Diagram...
Page 30: ...30 Fig 38 50LC 14 26 460V 575V 3 Phase Power Wiring Diagram...