4
SUPPLY FAN (BLOWER) SECTION
Supply Fan (Belt-Drive)
The supply fan system consists of a forward-curved centrifugal
blower wheel on a solid shaft with two concentric type bear-
ings, one on each side of the blower housing. A fixed-pitch
driven pulley is attached to the fan shaft and an adjustable-
pitch driver pulley is on the motor. The pulleys are connected
using a “V” type belt. (See Fig. 5.)
Fig. 5 — 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 Part Number “Belt Tension Checker” or equivalent
tool); tension should be 6-lbs at a
5
/
8
-in. deflection when mea-
sured at the centerline of the belt span. This point is at the cen-
ter 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 belt tension by loosening the motor mounting plate
front bolts and rear bolt and sliding the plate toward the fan (to
reduce tension) or away from fan (to increase tension). Ensure
the blower shaft and the motor shaft are parallel to each other
(pulleys aligned). Tighten all bolts when finished.
To replace the belt:
1. Use a belt with same section type or similar size. Do not
substitute a “FHP” type belt. When installing the new belt,
do not use a tool (screwdriver or pry-bar) to force the belt
over the pulley flanges, this will stress the belt and cause a
reduction in belt life.
2. Loosen the motor mounting plate front bolts and rear
bolts.
3. Push the motor and its mounting plate towards the blower
housing as close as possible to reduce the center distance
between fan shaft and motor shaft.
4. Remove the belt by gently lifting the old belt over one of
the pulleys.
5. Install the new belt by gently sliding the belt over both
pulleys and then sliding the motor and plate away from the
fan housing until proper tension is achieved.
6. Check the alignment of the pulleys, adjust if necessary.
7. Tighten all bolts.
8. Check the tension after a few hours of runtime and re-
adjust as required.
ADJUSTABLE-PITCH PULLEY ON MOTOR
The motor pulley is an adjustable-pitch type that allows a ser-
vicer to implement changes in the fan wheel speed to match as-
installed ductwork systems. The pulley consists of a fixed
flange side that faces the motor (secured to the motor shaft)
and a movable flange side that can be rotated around the fixed
flange side that increases or reduces the pitch diameter of this
driver pulley. (See Fig. 6.)
Fig. 6 — Supply-Fan Pulley Adjustment
As the pitch diameter is changed by adjusting the position of
the movable flange, the centerline on this pulley shifts laterally
(along the motor shaft). This creates a requirement for a re-
alignment of the pulleys after any adjustment of the movable
flange. Also, reset the belt tension after each realignment.
Check the condition of the motor pulley for signs of wear.
Glazing of the belt contact surfaces and erosion on these sur-
faces are signs of improper belt tension and/or belt slippage.
Pulley replacement may be necessary.
To change fan speed:
1. Shut off unit power supply.
2. Loosen belt by loosening fan motor mounting nuts. (See
Fig. 5.)
3. Loosen movable pulley flange setscrew. (See Fig. 6.)
4. Screw movable flange toward fixed flange to increase
speed and away from fixed flange to decrease speed.
Increasing fan speed increases load on motor. Do not
exceed maximum speed specified.
5. Set movable flange at nearest keyway of pulley hub and
tighten setscrew to torque specifications.
To align fan and motor pulleys:
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft. Make angular alignment
by loosening motor from mounting.
3. Tighten fan pulley setscrews and motor mounting bolts to
torque specifications.
4. Recheck belt tension.
WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before performing service or maintenance operations on the
fan system, shut off all unit power and tag-out the unit
disconnect switch. Do not reach into the fan section with
power still applied to the unit.
STRAIGHT EDGE
MUST BE PARALLEL
WITH BELT
SETSCREWS
MOTOR AND
FANSHAFTS
MUST BE
PARALLEL
FIXED FLANGE
MOVABLE
FLANGE
SINGLE - GROOVE
FAN PULLEY
MOTOR PULLEY
Содержание Puron R-410A
Страница 29: ...29 Fig 44 RTU Open Overlay for Economizer Wiring ...
Страница 30: ...30 Fig 45 VFD Overlay for W2770 Controller Wiring ...
Страница 50: ...50 Fig 63 50KC Typical Unit Wiring Diagram Power 06A 208 230 3 60 ...
Страница 51: ...51 Fig 64 50KC Unit Wiring Diagram Control A06 ...
Страница 76: ...76 Fig B Unit Wiring Diagram Controls for Sizes A04 A06 208 230 1 60 208 230 3 60 460 3 60 575 3 60 ...
Страница 77: ...77 Fig C Unit Wiring Diagram Power for Sizes A04 and A06 208 230 1 60 ...
Страница 78: ...78 Fig D Unit Wiring Diagram Power for Size A05 208 230 1 60 ...
Страница 79: ...79 Fig E Unit Wiring Diagram Power for Sizes A04 A06 208 230 3 60 460 3 60 575 3 60 ...
Страница 80: ...80 APPENDIX F MOTORMASTER SENSOR LOCATIONS Fig F 50KC A04 Outdoor Circuiting Fig G 50KC A05 Outdoor Circuiting ...
Страница 81: ...81 Fig H 50KC A06 Outdoor Circuiting ...