Trane QFNA-IOM-1 - Manual (Page 20)

Start-Up Procedures
The following items must be
checked before initial start-up of
the fan:
1. Check all bolts, setscrews, and
locking collars on the fan,
bearings, drive, motor mount, and
accessories for tightness. See
Tables 4, 5, 10, 11 and 13.
2. Turn the fan wheel by hand to be
sure it does not strike any portion
of the housing. See Table 3 for tip
clearance for tip clearance.
3. Recheck bearing alignment and
lubrication.
4. Operate the variable inlet vanes
to be sure they move freely and
position properly.
5. Repair any coating flaws in units
with special protective coatings.
6. Check switches and wiring to
motor.
7. Check fan and duct for dirt and
debris and close all access doors.
Foreign material in the inlet cone
can cause wheel imbalance.
8. Check belt alignment and tension
as follows:
• Tighten the belts slightly and
manually rotate the drive several
times.
• On multiple belt drives, determine
that the force of deflection is
approximately the same by
pushing each belt in an equal
distance at a point halfway from
each sheave. If this force is not
the same for each belt, the motor
and fan shaft are not parallel.
Realign as required.
• After realignment, tighten the belts
again to a reasonable tension.
• Operate the unit a few minutes to
allow belts to seat. Belts should
not slip when running,but a slight
squeal at start-up is normal. DO
NOT OVER-TENSION BELTS.
• Belt tension should be rechecked
after 8 hours of operation and
monthly thereafter. When the belt
is in operation, the tight side of
the belt should form a straight line
from sheave with only a slight bow
on the slack side.
At initial start-up, check the fan wheel
for proper rotation. When facing the
inlet, the wheel must rotate
clockwise.
If the fan has inlet vanes, they can be
partially closed to lower power
requirements at start-up. On fans
with multi-speed motors, run initial
checkout at low speed.
Pay particular attention to any
vibration, noise or overheating of the
fan bearings and motor (bearings
may run warm during break in).
Vibration is the most common
problem encountered during start-up.
If the vibration is significant, it must
be corrected before allowing the fan
to operate continuously. See Table 8.
The “Trouble Shooting” section of
this manual details the common
causes for vibration. If the problem is
diagnosed as fan wheel imbalance,
use a vibration analyzer to rebalance
the fan. The addition of any balance
weights can be made on the inlet
cone. See Figure 11.
Determining Fan RPM
Q Fans and Super II Fans with
factory installed motor and drive are
shipped with the correct Fan RPM.
However, if the motor and drive are
field installed and the Fan RPM
needs to be set or checked, the
following procedure can be used:
Fan RPM can best be determined by
using a strobe-type tachometer. If
such an instrument is not available,
approximate RPM can be derived as
follows:
1. Remove belt guard and mark
motor sheave.
2. By hand, rotate the fan wheel 10
times while counting revolutions
of motor sheave to the nearest
quarter turn.
3. Divide the nameplate motor RPM
by the number of revolutions of
the motor sheave and multiply by
10. This is Fan RPM.
Example: If motor sheave revolves
8-1/4 turns - - Motor nameplate
states 1750 RPM.
1750 x 10 = 2121 RPM
8-1/4
20 QFNA-IOM-1
Start-Up Q Fans and Super Q II
Table 8 - Maximum Allowable Vibration on Trane Model Q Fans
Fan Size Fan RPM Vert, Horiz, and Axial
Fans
16-44 All Speeds 5 Mils
49-60 Up to 1000 4 Mils
49-60 1000 & Up 3 Mils