Crankcase Heaters - Daikin WGZ030DW Installation And Maintenance Manual

System Maintenance
Oil can be added to the compressor through the oil fill hole in
the crankcase. Special equipment is required to add oil and the
work should be done by qualified refrigeration technicians
with the proper training and equipment.
!
POE oil must be handled carefully using proper protective
equipment (gloves, eye protection, etc.) The oil must not come
in contact with certain polymers (e.g. PVC), as it may absorb
moisture from this material. Also, do not use oil or refrigerant
additives in the system.
Sightglass and Moisture Indicator
The refrigerant sight glasses should be observed periodically.
A monthly observation should be adequate. A clear glass of
liquid indicates that there is adequate refrigerant charge in the
system to provide proper feed through the expansion valve.
The sight glass should be clear when:
• Ambient temperature is above 75°F (23°C)
• Both compressors on a circuit are running
• All fans on a circuit are running
Bubbling refrigerant in the sight glass may occur at other
conditions and may indicate that the system is short of
refrigerant charge. Refrigerant gas flashing in the sight glass
could also indicate an excessive pressure drop in the line,
possibly due to a clogged filter-drier or a restriction elsewhere
in the system. An element inside the sight glass indicates what
moisture condition corresponds to a given element color. If the
sight glass does not indicate a dry condition after about 12
hours of operation, the unit should be pumped down and the
filter-driers changed.
If the system is suspected of being short of refrigerant, a
qualified service technician with EPA certification should be
contacted to thoroughly check out the unit and add refrigerant
if necessary.

Crankcase Heaters

The compressors are equipped with crankcase heaters. The
function of the heater is to keep the temperature in the
crankcase high enough to prevent refrigerant from migrating to
the crankcase and condensing in the oil during off-cycle. When
a system is to be started up initially, the power to the heaters
should be turned on for at least 12 hours before the
compressors are started. The crankcase should be up to about
80°F (26.7°C) before the system is started up, to minimize
lubrication problems or liquid slugging of compressor on start-
up.
If the crankcase is cool (below 80°F) (26.7°C) and the oil level
in the sight glass is full to top, allow more time for oil to warm
before starting the compressor.
The crankcase heaters are on whenever power is supplied to
the unit and the compressor is not running.
56
WARNING
Phase/Voltage Monitor (Optional)
The phase/voltage monitor is a device that provides protection
against three-phase electrical motor loss due to power failure
conditions, phase loss, and phase reversal. Whenever any of
these conditions occur, an input relay is deactivated,
disconnecting power to the thermostatic control circuit. The
compressor does a rapid shutdown pump down.
The input relay remains deactivated until power line
conditions return to an acceptable level. Trip and reset delays
prevent nuisance tripping due to rapid power fluctuations.
When three-phase power has been applied, the input relay
should close and the "run light" should come on. If the relay
does not close, perform the following tests.
Check the voltages between L1-L2, L1-L3, and L2-L3.
1
Voltages should be approximately equal and within
+10% of the rated three-phase line-to-line voltage.
If these voltages are extremely low or widely
2
unbalanced, check the power system to determine the
cause of the problem.
If the voltages are good, turn off the power and
3
interchange any two of the supply power leads at the
disconnect switch. This may be necessary, as the phase/
voltage monitor is sensitive to phase reversal. Turn on
the power. The relay should now close after the
appropriate delay.
Factory settings are as follows:
• Voltage Setting: set at nameplate voltage.
• Trip Delay Time: 2 seconds
• Restart Delay Time: 60 seconds
Hot Gas Bypass (Optional)
This option allows passage of discharge gas to the evaporator,
permitting operation at lower loads than available with
compressor unloading. It also keeps the velocity of refrigerant
gas high enough for proper oil return at light load conditions.
The pressure regulating valve is factory set to begin opening at
69 psig and can be changed by changing the pressure setting.
The adjustment range is 0 to 100 psig. To raise the pressure
setting, remove the cap on the bulb and turn the adjustment
screw clockwise. To lower the setting, turn the screw
counterclockwise. Do not force the adjustment beyond the
range it is designed for, as this will damage the adjustment
assembly. The regulating valve opening point can be
determined by slowly reducing the system load while
observing the suction pressure. When the bypass valve starts to
open, the refrigerant line on the evaporator side of the valve
will begin to feel warm to the touch.
The hot gas line can become hot enough to cause personal
injury in a very short time. Avoid contact when it is operating or
during cool-down period.
CAUTION
IM 1131-2