Bard WA721 - Manual (Page 16)

Manual 2100-425
Page 14
START UP
IMPORTANT INSTALLER NOTE
For improved start-up performance, wash the indoor
coil with a dishwasher detergent.
CRANKCASE HEATERS
WA611, WA70 and WA721 units are provided with
compressor crankcase heat.
The WA611, WA70 and WA721 models have a band
type heater located around the bottom of the
compressor. This heater is controlled by the crankcase
heater relay. The heater is only energized when the
compressor is not running.
Some form of crankcase heat is essential to prevent
liquid refrigerant from migrating to the compressor,
casing oil pump out on compressor start-up and
possible valve failure due to compressing a liquid.
The decal in Figure 9 is affixed to all WA611, WA70
and WA721 units detailing start-up procedure. This is
very important. Please read carefully.
HIGH PRESSURE SWITCH
The WA611, WA70 and WA721 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 change 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.
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
tabulated values.
The direction of rotation of the compressor may be
changed by reversing any two line connections to the
unit.
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
disconnect 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 properly elapsed time, the
thermostat may be set to operate the
compressor.
5. Except as required for safety while
servicing – Do not open system
disconnect switch.
7961-061
FIGURE 9
START-UP LABEL