JOHNSON CONTROLS
15
FORM 160.77-O1
ISSUE DATE: 10/22/2020
SECTION 2 - SYSTEM OPERATING PROCEDURES
OIL HEATERS
This section along with the
YKEP Startup Checklist
(Form 160.77-CL2)
details the process and procedures
used to startup and operate the YKEP chiller. If the oil
heater is de-energized during a shutdown period, it
must be energized for 12 hours prior to starting com-
pressor, or remove all oil and recharge compressor with
new oil. (See Oil Charging Procedure on page 21.)
Oil Heater Operation
The oil heater operation is controlled by the YKEP
Control Center. The heater is turned on and off to main-
tain the oil temperature differential to a value 50°F
(27.8°C) above the condenser saturation temperature.
This target value is maintained by the control panel.
If the target value is greater than 160°F (71°C), the tar-
get defaults to 160°F (71°C). If the target value is less
than 110°F (43.3°C), it defaults to 110°F (43.3°C).
To prevent overheating of the oil in the event of a con-
trol center component failure, the oil heater thermostat
(1HTR) is set to open at 180°F (82°C).
Checking the Oil Level in the Oil Reservoir
During operation, the proper oil level should fall into
the “Operating Range” identified on the vertical oil
level indicator label located on the oil reservoir cover
plate.
• If the oil level during operation is in the “Over
Full” region of the oil level indicator, oil should
be removed from the oil reservoir.
• If the oil level during operation is in the “Low
Oil” region of the oil level indicator, oil should
be added to the oil reservoir. (See Oil Charging
Procedure, page 20.)
Always comply with EPA and Local regu-
lations when removing or disposing of
Refrigeration System Oil.
FIGURE 6 -
OIL LIVEL INDICATOR
LD08647
PRE-STARTING
Prior to starting the chiller, observe the Control Center
Refer to the
YKEP Control Panel Operations Manual
(Form 160.77-O2).
Make sure the display reads "SYS-
TEM READY TO START".
Vent any air from the chiller water boxes
prior to starting the water pumps. Failure
to do so will result in pass baffle damage.
START-UP
1. If the chilled water pump is manually operated,
start the pump. The Control Center will not al-
low the chiller to start unless chilled liquid flow
is established through the unit. If the chilled liq-
uid pump is wired to the Microcomputer Control
Center, the pump will automatically start; there-
fore this step is not necessary.
2. To start the chiller, press the
COMPRESSOR
START
button on the control panel. When the
start switch is energized, the Control Center is
placed in an operating mode and any malfunction
will be noted by messages on the graphic display.
For display messages and information pertaining
to the operation of the YKEP Control Center, re-
fer to the
YKEP Control Panel Operations Manu-
al (Form 160.77-O2)
.
Any malfunctions which occur during
SHUTDOWN are also displayed and
recorded.
CHILLER OPERATION
The chiller will vary capacity to maintain the leav-
ing
CHILLED LIQUID TEMPERATURE
setpoint
through a specific sequencing of optional hot gas by-
pass, pre-rotation vanes, and compressor speed.
Throughout capacity control, the compressor speed is
maintained above the minimum required for the pre-
vailing head condition, to avoid surge. Otherwise, the
device maintaining capacity is controlled by a pro-
portional-integral-derivative (PID) control based on
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