Two-Speed Indoor Fan Motor System; 2-Speed Fan With Variable Frequency; Drive (Vfd) - Bryant Preferred Series Service And Maintenance Instructions

REPLACING THE V-BELT
1. Use a belt with same section type or similar size. Do not
substitute a "FHP" or "notched" type V-belt.
2. Loosen (turn counterclockwise) the motor mounting plate
front bolts and rear bolts. See Fig. 4.
3. Loosen (turn counterclockwise) the jack bolt lock nuts.
Loosen (turn counterclockwise) the jack bolts relieving the
belt tension allowing easy removal of the belt by hand.
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, then tighten (turn clockwise) the jack bolts sliding
the motor plate away from the fan housing until proper
belt tension is achieved.
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in premature wear
and damage to equipment.
Do not use a screwdriver or a pry bar to place the new V-belt in
the pulley groove. This can cause stress on the V-belt and the
pulley resulting in premature wear on the V-belt and damage
to the pulley.
6. Check the alignment of the pulleys and adjust if necessary.
See Fig 6.
7. Tighten all bolts attaching the motor to the motor plate.
8. Tighten all jack bolt jam nuts by turning clockwise.
9. Check the tension after a few hours of runtime and re-
adjust as required. See Fig. 5.
ADJUSTABLE-PITCH PULLEY ON MOTOR
The motor pulley is an adjustable-pitch type that allows a servicer
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.
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 realignment of
the pulleys after any adjustment of the movable flange. Also reset
the belt tension after each realignment. The factory setting of the
adjustable pulley is five turns open from full closed.
Check the condition of the motor pulley for signs of wear. Glazing
of the belt contact surfaces and erosion on these surfaces are signs
of improper belt tension and/or belt slippage. Pulley replacement
can be necessary.
CHANGING FAN SPEED:
1. Shut off unit power supply and apply approved lock-out/
tag-out procedures.
2. Loosen belt by loosening the motor adjustment bolts as
described in the Belt Adjustment section above. See
Fig. 4.
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 fan speed in the product data or motor
amperage as listed on the unit rating plate.
5. Set movable flange at nearest keyway or flat of pulley hub
and tighten setscrew to torque specifications. Torque pul-
ley set screw to 72 ± 5 in.-lb (8.14 ± 0.56 Nm).
ALIGNING THE FAN AND MOTOR PULLEYS:
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft. Make angular alignment
by loosening motor from mounting. See Fig. 6.
3. Tighten fan pulley setscrews and motor mounting bolts to
torque specifications.
4. Recheck belt tension. See Fig. 5.
FAN PULLEY
MOTOR AND
FANSHAFTS
MUST BE
PARALLEL
MOTOR PULLEY
Fig. 6 — Supply-Fan Pulley Adjustment
BEARINGS
This fan system uses bearings featuring concentric split locking
collars. The collars are tightened through a cap screw bridging the
split portion of the collar. The cap screw has a Torx T25 socket
head. To tighten the locking collar: Hold the locking collar tightly
against the inner race of the bearing and torque the cap screw to 65
to 70 in.-lb (7.4-7.9 Nm). See Fig. 7.
Fig. 7 — Tightening Locking Collar

TWO-SPEED INDOOR FAN MOTOR SYSTEM:

2-SPEED FAN WITH VARIABLE FREQUENCY

Two-Speed Indoor Fan Motor System
NOTE: The 2-speed indoor fan motor option is not available on
units with Perfect Humidity™ adaptive humidification system.
The 2-speed indoor fan motor system utilizes a fan speed control
board and Variable Frequency Drive (VFD) to automatically ad-
just the indoor fan motor speed in sequence with the unit's venti-
lation, cooling and heating operation. Conforming to ASHRAE
90.1 2010 Standard Section 6.4.3.10.b, during the first stage of
cooling operation the 2-speed indoor fan motor system will ad-
just the fan motor to provide two-thirds (
flow rate for the unit. When the call for the second stage of cool-
ing is required, the 2-speed indoor fan motor system will allow
the design airflow rate for the unit established (100%). During
the heating mode, the 2-speed indoor fan motor system will al-
low total design airflow rate (100%) operation. During ventila-
tion mode, the 2-speed indoor fan motor system will operate the
fan motor at 2 / speed.
3
5
STRAIGHT EDGE
MUST BE PARALLEL
WITH BELT
SETSCREWS
FIXED FLANGE
SINGLE - GROOVE
LOCKING COLLAR
T--- 25 TORX SOCKET
HEAD CAP SCREW

DRIVE (VFD)

2 / ) of the design air-
3
MOVABLE
FLANGE