Requirements/Adjustments And Data For Blower Units - Modine Manufacturing PTX Installation And Service Manual

INSTALLATION
To Install
1. Remove and discard the motor tie down strap and the
shipping block beneath the motor adjustment screw (not used
on all models.)
2. For 3 and 5 HP motors, affix sheave to the motor shaft and
install motor on the motor mounting bracket. Install belt on
blower and motor sheaves.
Figure 20.1 - Blower Model
MOUNTING BRACKETS ON BLOWER
ASSEMBLY
BLOWER BLOWER
SHEAVE HOUSING
3. Adjust motor adjusting screw for a belt deflection of
approximately 3/4" with 5 pounds of force applied midway
between the sheaves (refer to Figure 20.3). Since the belt
tension will decrease dramatically after an initial run-in period,
it is necessary to periodically re-check the tension. Excessive
tension will cause bearing wear and noise.
4. The blower bearings are lubricated for life; however, before
initial unit operation the blower shaft should be lubricated at
the bearings with SAE 20 oil. This will reduce initial friction
and start the plastic lubricant flowing.
5. Make electrical connections according to the wiring diagram.
6. Check rotation of the blower. Motor should be in clockwise
rotation when facing motor pulley. If rotation is incorrect,
correction should be made by interchanging wiring within the
motor. See wiring diagram on the motor.
7. The actual current draw of the motor should be determined.
Under no condition should the current draw exceed that
shown on the motor rating plate.
8. It is the installer's responsibility to adjust the motor sheave to
provide the specified blower performance as listed on pages
22 & 23 for blower settings different from the factory set
performance. The drive number on the unit may be identified
by referring to the Power Code number on the serial plate of
the unit (see page 31 for model number nomenclature) and
matching that number with those shown on page 21. From
the listing, the drive number can be determined.
20
MOTOR MOUNTING
BRACKET
MOTOR ADJUSTABLE
ADJUSTMENT MOTOR SHEAVE
SCREW
Blower Adjustments
Following electrical connections, check blower rotation to assure
blow-through heating. If necessary interchange wiring to reverse
blower rotation. Start fan motor and check blower sheave RPM
with a hand-held or strobe-type tachometer. RPM should check
out with the speeds listed in performance data shown on pages
22 and 23. A single-speed motor with an adjustable motor
sheave is supplied with these units. If blower fan speed
changes are required, adjust motor sheave as follows:
NOTE: Do not fire unit until blower adjustment has been
made or unit may cycle on limit (overheat) control.
1. Shut-off power before making blower speed
adjustments. Refer to "Determining Blower Speed" on
page 19 and to "Performance Data" on pages 22 and 23 to
determine proper blower RPM.
2. Loosen belt and take belt off of motor sheave.
3. Loosen set screw on outer side of adjustable motor sheave
(see Figure 20.2).
4. To reduce the speed of the blower, turn outer side of motor
sheave counterclockwise.
5. To increase the speed of the blower, turn outer side of motor
sheave clockwise.
6. Retighten motor sheave set screw, replace belt and
retighten motor base. Adjust motor adjusting screw such
that there is 3/4" belt deflection when pressed with 5 pounds
of force midway between the blower and motor sheaves
(see Figure 20.3). Since the belt tension will decrease
dramatically after an initial run-in period, it is necessary to
periodically re-check the tension to assure continual proper
belt adjustment.
7. Check to make certain motor sheave and blower sheave are
aligned. Re-align if necessary.
8. Re-check blower speed after adjustment.
9. Check motor amps. Do not exceed amps shown on motor
nameplate. Slow blower if necessary.
10. Check air temperature rise across unit. Check temperature
rise against values shown in performance tables on pages
22 and 23 to assure actual desired air flow is being achieved.
11. If adjustments are required, recheck motor amps after final
blower speed adjustment.
Figure 20.2 - Motor Sheave Adjustment
TOWARD MOTOR
Figure 20.3 - Belt Tension Adjustment
6-534.1
SET SCREW
ADJUSTABLE HALF
OF SHEAVE
3/4" DEFLECTION
WITH 5 LBS. FORCE