Manual 2100-410
Page 17
START UP
IMPORTANT INSTALLER NOTE
For improved start up performance wash the indoor coil
with a dish washing detergent.
CRANKCASE HEATERS
SH491-B and -C are provided with compressor
crankcase heat. All other models are not provided with
crankcase heat. They are either single phase or the
system refrigerant charge is not of sufficient quantity to
require crankcase heat.
The SH491-B and -C models have a wrap around type
heater located on the lower section of the compressor
housing. This is an on/off heater that is controlled by
the compressor contactor.
The label in Figure 13 is affixed to all SH491-B and -C
units detailing start up procedure. This is very
important. Please read carefully.
HIGH PRESSURE SWITCH
All models are supplied with a remote reset high
pressure switch. If tripped, this pressure switch may be
reset by turning the thermostat off then back on again.
THREE PHASE SCROLL COMPRESSOR
START UP INFORMATION
Scroll compressors, like several other types of
compressors, will only compress in one rotational
direction. Direction of rotation is not an issue with
single phase compressors since they will always start
and run in the proper direction.
However, three phase compressors will rotate in either
direction depending upon phasing of the power. Since
there is a 50-50 chance of connecting power in such a
way as to cause rotation in the reverse direction,
verification of proper rotation must be made. All three
phase units incorporate a phase monitor to ensure
proper field wiring. See the “Phase Monitor” section
later in this manual.
Verification of proper rotation must be made any time
a compressor is changed or rewired. If improper
rotation is corrected at this time there will be no
negative impact on the durability of the compressor.
However, reverse operation for over one hour may have
a negative impact on the bearing due to oil pump out.
NOTE: If compressor is allowed to run in reverse
rotation for several minutes, the
compressor’s internal protector will trip.
FIGURE 13
START UP LABEL
IMPORTANT
THESE PROCEDURES MUST BE
FOLLOWED AT INITIAL START UP
AND AT ANY TIME POWER HAS
BEEN REMOVED FOR 12 HOURS
OR LONGER.
To prevent compressor damage which
may result from the presence of liquid
refrigerant in the compressor crankcase:
1.
Make certain the room thermostat is in
the “off“ position. (The compressor is
not to operate.)
2.
Apply power by closing the system dis-
connect switch. This energizes the
compressor heater which evaporates
the liquid refrigerant in the crankcase.
3.
Allow 4 hours or 60 minutes per pound
of refrigerant in the system as noted on
the unit rating plate, whichever is
greater.
4.
After proper elapsed time the thermo-
stat may be set to operate the
compressor.
5.
Except as required for safety while ser-
vicing, do not open system disconnect
switch.
7961-411
All three phase ZR3 compressors are wired identically
internally. As a result, once the correct phasing is
determined for a specific system or installation,
connecting properly phased power leads to the same
Fusite terminal should maintain proper rotation
direction.
Verification of proper rotation direction is made by
observing that suction pressure drops and discharge
pressure rises when the compressor is energized.
Reverse rotation also results in an elevated sound level
over that with correct rotations, as well as, substantially
reduced current draw compared to tabulate values.
The direction of rotation of the compressor may be
changed by reversing any two line connections to the
unit.
