Carrier 48TC 17 Series, Инструкции по обслуживанию и техническому обслуживанию, Страница: 8 / 96

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25.
Adjust the V-belt tension using the adjustment tool.
26.
Turn the two jack bolts clockwise, moving the motor
assembly away from the blower pulley, increasing the
V-belt tension.
27.
Tighten the four bolts securing the motor mounting
brackets to the unit. Torque bolts to 120
±
12 in-lbs
(14
±
1.4 Nm).
28.
Remove the cover on the motor connection box.
29.
Re-connect all electrical leads to the motor and re­
place the connection box cover.
30.
Re-connect all electrical power to the unit. Remove
lockout tags on all electrical power sources.
31.
Start the unit and allow to run for a designated period.
32.
Shut off the unit and make any necessary adjustments
to the V-belt tension or the motor and blower wheel
pulley alignment.
BROWNING BELT
TENSION CHECKER
STRAIGHTEDGE
1/2”
(1.3 cm)
BELT
DEFLECTION
C12093
Fig. 11 − Adjusting V − belt Tension
Changing Fan Wheel Speed by Changing Pulleys
The horsepower rating of the belt is primarily dictated by
the pitch diameter of the smaller pulley in the drive
system (typically the motor pulley in these units). Do not
install a replacement motor pulley with a smaller pitch
diameter than provided on the original factory pulley.
Change fan wheel speed by changing the fixed fan pulley
(larger pitch diameter to reduce wheel speed, smaller
pitch diameter to increase wheel speed) or select a new
system with both pulleys and matching belt(s).
Before changing pulleys to increase fan wheel speed,
check the fan performance at the target speed and airflow
rate to determine new motor loading (bhp). Use the fan
performance tables or use the Packaged Rooftop Builder
software program. Confirm that the motor in this unit is
capable of operating at the new operating condition. Fan
shaft loading increases dramatically as wheel speed is
increased.
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in equipment
damage.
Drive packages cannot be changed in the field. For
example: a standard drive cannot be changed to a high
static drive. This type of change will alter the unit’s
certification and could require heavier wiring to support
the higher amperage draw of the drive package.
CAUTION
!
NOTE :
Drive packages cannot be changed in the field.
For example: a standard drive cannot be changed to a high
static drive. This type of change will alter the unit’s
certification and could require heavier wiring to support
the higher amperage draw of the drive package.
To reduce vibration, replace the motor’s adjustable pitch
pulley with a fixed pitch pulley (after the final airflow
balance adjustment). This will reduce the amount of
vibration generated by the motor/belt-drive system.
To determine variable pitch pulley diameter, perform the
following calculation:
1.
Determine full open and full closed pulley diameter.
2.
Subtract the full open diameter from the full closed
diameter.
3.
Divide that number by the number of pulley turns
open from full closed
This number is the change in pitch datum per turn
open.
EXAMPLE:
–
Pulley dimensions 2.9 to 3.9 (full close to full open)
–
3.9 - 2.9 = 1
–
1 divided by 5 (turns from full close to full open)
–
0.2 change in pulley diameter per turn open
–
2.9 + 0.2 = 3.1” pulley diameter when pulley closed
one turn from full open
CONDENSER COIL SERVICE
ROUND TUBE PLATE FIN (RTPF)
CONDENSER COIL
The condenser coil is fabricated with round tube copper
hairpins and plate fins of various materials and/or coatings
(see the Model Number Nomenclature in Appendix I to
identify the materials provided in this unit). The coil may
be one − row or composite − type two − row. Composite
two − row coils are two single − row coils fabricated with a
single return bend end tubesheet.
Recommended Condenser Coil Maintenance
and Cleaning
Routine cleaning of coil surfaces is essential to maintain
proper operation of the unit. Elimination of contamination
and removal of harmful residues will greatly increase the
life of the coil and extend the life of the unit. The
following maintenance and cleaning procedures are