York YD A, Operating & Maintenance, Page: 19 / 52

JOHNSON CONTROLS
19
SECTION 1 – DESCRIPTION OF SYSTEM AND FUNDAMENTALS OF OPERATION
FORM 160.69-O2
ISSUE DATE: 9/30/2020
1
FIGURE 2 – CHILLER OPERATION FLOW CHART - (CONT'D)
LD10491
2 Compressors Running
(from Page 3)
Electro Mechanical Starter
Chiller Soft Shutdown
Close vanes on
both compressors
Chiller normal
or cycling stop
signal
Yes
Disch Valves closed
Both compressors?
No >40 Sec
Close Discharge Valves
on both compressors
Stop both compressor
motors.
Post Lube Run time
both compr oil pumps
Energize Oil Heater
1 Compressor Running
(from Page 1 or 4)
Chiller normal
or cycling stop
signal
Stop Lead compressor
motor
Post Lube Run time
lead compr oil pump
Energize Oil Heater
System Standby
Alarm/Fault.
Proceed to stop
motors
PRV Motor Switches
Closed or 150 Seconds
Close vanes on
Lead compressor
Yes
Disch Valves closed
Both compressors?
No >40 Sec
Close Discharge Valves
on Lead compressor
Alarm/Fault.
Proceed to stop
lead motor
PRV Motor Switch Closed
or 150 Seconds
YD Dual Compressor Chiller