AAON LZ Series, Installation Operation & Maintenance

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Three phase voltage imbalance will cause
motor overheating and premature failure.
The maximum allowable imbalance is 5%.
Voltage imbalance is defined as 100 times the
maximum deviation from the average voltage
divided by the average voltage.
Example:
(218V+237V+235V)/3
= 230V, then
100*(230V-218V)/230V = 5.2%, which
exceeds the allowable imbalance.
Check voltage imbalance at the unit
disconnect switch and at the compressor
terminal. Contact your local power company
for line voltage corrections.
Variable Speed Compressors
Variable speed compressors should not be
operated outside the factory determined
frequency range. The factory determined
compressor VFD frequency range is given
below in Table 5
Table 5- Tandem Circuited Variable Speed
Compressor VFD Frequency Range
Model LZ-
Air-
Cooled
Model LZ -
Evap-
Condensed
Compressor
VFD Range
(Hz)
208V, 230V, 460V and 575V Units
045, 055,
060
053, 061,
069
45-65Hz
075 078 45-70Hz
095, 105,
120, 200,
245, 315,
385
106, 121,
134, 274,
356, 441
35-60 Hz
140, 170,
280, 350,
420
161, 193,
239, 319,
401, 478
35-65 Hz
Evaporative-Condensed Chiller Field Piping
Connections
There are at least two field water connections
that must be made for the evaporative-
condensed chiller. There is a 3/4” MPTF
copper fitting city make up water connection
and a 2” PVC socket drain connection, as
shown in
Figure 26. This drain should connect to a
sanitary sewer or other code permitted drain.
These connections can go through the base or
the wall of the unit.
There is a cutout in the base with a cap that is
1” tall and the cap is sealed to the unit base to
prevent any leaks in the unit from penetrating
into the building. Any piping through the
base should go through a field cutout in this
Rotation must be checked on all
MOTORS AND COMPRESSORS of
three phase units. Condenser fan
motors should all be checked by a
qualified service technician at startup
and any wiring alteration should only
be made at the unit power connection.
Variable
frequency drives are
programmed to automatically rotate
the fan in the correct rotation. Do not
rely on fans with variable frequency
drives for compressor rotation.
CAUTION
No variable speed compressor shall
operate below 35 Hz. Operating
variable speed compressors outside
the frequency range specified in this
manual voids all warranties and may
result in compressor failure.
CAUTION