Nordyne Light Commercial Air Handler B5SM -090 - Manual (Page 8)

8
STARTUP AND ADJUSTMENTS
Pre-Start Check List
Prior to start-up, complete the following inspection:

Verify the unit is level and condensate can drain. Check
condensate drain line(s) for proper slope and trap.

Verify the air handler is mounted securely.

Verify the surrounding area and top of the unit is free
from obstructions and debris.

Check all ductwork connections. Make sure the duct
work is adequetly sealed to prevent air leakage.

Check all coil connections for leaks.

Verify that the line voltage power leads are securely
connected and the unit is properly grounded.

Verify that the low voltage wires are securely connected
to the correct leads on the low voltage terminal strip.
Make sure the thermostat is wired correctly.

Verify the blower rotates properly. Check the blower belt
between the pulleys for proper tension and alignment.

Verify the power supply branch circuit overcurrent
protection is sized properly.

Verify all fi lters are in place and all equipment access/
control panels are in place
Motor Sheave Adjustment
The motor sheave consists of an outer, moveable pulley
face and an inner stationary face. To adjust the motor
sheave,
1. Relieve the belt pressure by loosening motor mount
bolts and the belt tensioning bolts on the motor mount.
2. Move the blower fan belt out of the way (if necessary)
and loosen the set screw in the outer sheave face.
3. Rotate the face in increments of one half or full turns
only. NOTE: This maintains the set screw position
precisely over the fl ats on the pulley hub. Rotating the
sheave clockwise (when viewed from the lead end of
motor - opposit end of shaft) will make the blower run
slower which decreases airfl ow. Rotating the sheave
counter clockwise (as viewed from lead end) will cause
the blower to speed up.
4. Tighten the setscrews after the desired adjustment has
been made and verify the moveable face is properly
secured.
Grounding
WARNING:
The unit cabinet must have an uninterrupted or
unbroken electrical ground to minimize personal
injury if an electrical fault should occur. Do not
use gas piping as an electrical ground!
This unit must be electrically grounded in accordance
with local codes or, in the absence of local codes, with
the National Electrical Code (ANSI/NFPA 70) or the CSA
C22.1 Electrical Code. Use the grounding lug provided in
the control box for grounding the unit.
Example :
AB = 451V
BC = 460V
AC = 453V
2. Determine the average voltage in the power supply.
3. Determine the maximum deviation:
4. Determine percent of
voltage imbalance by
using the results from
steps 2 & 3 in the following
equation.
max voltage deviation
from average voltage
= 100 x
average voltage
% Voltage Imbalance
6
454
100 x = 1.32%
Example:
1. M e a s u r e t h e l i n e
voltages of your 3-phase
power supply where it
enters the building and
at a location that will
only be dedicated to the
unit installation. (at the
units circuit protection or
disconnect).
Unbalanced 3-Phase Supply Voltage
Voltage unbalance occurs when the voltages of all phases
of a 3-phase power supply are no longer equal. This
unbalance reduces motor effi ciency and performance.
Some underlying causes of voltage unbalance may include:
Lack of symmetry in transmission lines, large single-phase
loads, and unbalanced or overloaded transformers. A
motor should never be operated when a phase imbalance
in supply is greater than 2%.
Perform the following steps to determine the percentage
of voltage imbalance:
In this example, the measured line voltages were
451, 460, and 453. The average would be 454 volts
(451 + 460 + 453 = 1,364 / 3 = 454).
The amount of phase imbalance (1.32%) is satisfactory
since the amount is lower than the maximum allowable
2%. Please contact your local electric utility company if
your voltage imbalance is more than 2%.
Example:
From the values given in step 1, the BC voltage
(460V) is the greatest difference in value from
the average:
460 - 454 = 6
454 - 451 = 3
454 - 453 = 1 Highest Value