Marvair Scholar III™ VAISA I&S Manual 03/2019 Rev. 8
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suction pressure drops and the discharge pressure rises when the compressor
is energized. An alternate method of verification for self contained system
with small critical refrigerant charges, where the installation of gauges may be
objectionable, can be made by monitoring the temperature of the refrigerant
lines at the compressor. The temperature should rise on the discharge line
while the suction line temperature decreases. Reverse rotation also results in a
substantially reduced current draw when compared to tabulated values.
There is no negative impact on durability caused by operating three phase
compressors in the reversed direction for a short duration of time, usually
defined as less than one hour. However, after several minutes of operation the
compressor's internal protector will trip. The compressor will then cycle on the
protector until the phasing is corrected. Reverse operation for longer than one
hour may have a negative impact on the bearings.
B. 1. Low voltage wiring must be class 1.
2. For Scholar III™ units with a remote (wall mounted) thermostat, route the low
voltage wiring from the point of entry into the cabinet, upward through the
raceway adjacent to the disconnect shown in Figure 5.
Route wires into the terminal strip compartment through the openings provided.
Connect wiring to the terminal strip as shown in Figure 9 for a remote, wall
mounted thermostat installation.
