104
YORK INTERNATIONAL
SYSTEM RUN – REMOTE LOAD LIMIT
System is running in REMOTE mode and the unit load-
ing is being inhibited by the remote load limit command
from a remote device. The load limit value that is in ef-
fect can be viewed by pressing the DISPLAY DATA key-
pad key. One of the scrolled messages is
“REMOTE LOAD
LIMIT = XXX%”.
The steam or hot water valve position will
be limited to this value during SYSTEM RUN.
The remote load limit command is input to the relay board
TB4-82 as a 1-11 second PWM signal directly from an
external energy management system or from the op-
tional card file inside the Control Center that accepts 4-
20mA, 0-10VDC or contact closure inputs (refer to YORK
Form 155.16-PA1). The load limit command can also be
input to the Micro Board RS-485 serial port TB7 from
the YORK FAX-4500 Energy Management System.
The load limit value is 100% to (10-20% as programmed;
the minimum allowable valve position is programmable
from 10% to 20%). The minimum allowable steam or hot
water valve position is factory set to 10%. It should only
be changed by a qualified service technician using YORK
“Service” manual, Form 155.16-M3.
SYSTEM RUN – LEAVING CHILLED WATER CONTROL
The system is running in LOCAL or REMOTE mode.
The loading and unloading is being automatically con-
trolled by the LEAVING CHILLED WATER TEMP
setpoint. There are no status messages.
SYSTEM RUN – PULL DOWN LIMIT
The system is running in LOCAL, REMOTE or SER-
VICE mode. The loading is being inhibited by the pro-
grammed PULL DOWN DEMAND setpoint.
SYSTEM RUN – MAXIMUM COOLING
The system is running in LOCAL, REMOTE or SER-
VICE operating mode and the steam or hot water valve
position has reached and is being limited to the “Max
Allowed Loading” setpoint value that has been pro-
grammed by the service technician. During unit com-
missioning, it is sometimes necessary to temporarily limit
the load to some value less than 100% because of local
or unit conditions. Details of programming this function
are included in the Control Center “Service” manual,
Form 155.16-M3 and should only be performed by a
qualified service technician.
SYSTEM RUN – AUTOMATIC DECRYSTALLIZATION
If the system is running and the Automatic Decrystalli-
zation Cycle (ADC) temperature increases to 160°F
(71.1°C), this message is displayed and the steam or
hot water valve position is limited to 50% for a minimum
of 10 minutes. Simultaneously, the stabilizer refrigerant
solenoid valve is energized for 2 minutes, transferring
refrigerant to the generator’s drain line and thus to the
shell side of the heat exchanger to dilute the solution.
After 10 minutes, if the ADC temperature falls to 150°F
(65.6°C), the cycle terminates; otherwise, the cycle re-
peats. The ADC operation will continue for at least 10
minutes regardless of a shutdown or subsequent restart.
Units equipped with Buffalo pumps (Micro Board pro-
gram jumper JP2 in) and EPROM version A.02F.02 or
later: If the refrigerant pump is not running when the
ADC is initiated, or the refrigerant pump shuts down
during the ADC, the standard ADC as described above
is not performed. Instead, a LIMITED ADC is performed.
The LIMITED ADC has two phases: PRIMARY and SEC-
ONDARY. Refer to messages “SYSTEM RUN – PRIMARY
LIMITED AUTO-DECRYST” and “SYSTEM RUN – SECONDARY
LIMITED AUTO-DECRYST”.
SYSTEM RUN – PRIMARY LIMITED AUTO-DECRYST
(EPROM version A.02F.02 or later; applicable only to
units equipped with Buffalo pumps, Micro Board program
jumper JP2 in)
The unit is running and performing a “Primary Limited
Automatic Decrystallization Cycle”. This variation of the
standard automatic decrystallization cycle (ADC) is per-
formed if the refrigerant pump is not running when a
standard ADC is initiated or is turned-off during a
standard ADC. LIMITED ADC have two phases: Primary
and Secondary (see below). The Primary Limited ADC
is the same as Standard ADC except it is performed for
10 minutes only and the stabilizer refrigerant solenoid
valve (2SOL) is not energized (opened) during the first
two minutes of the cycle, as would be done in a Stan-
dard ADC. If float switches 1F and 3F close to start the
refrigerant pump before the “Primary Limited ADC” ter-
minates, a normal ADC is performed. Otherwise, when
10 minutes have elapsed and the “Primary Limited ADC”
terminates, normal chiller operation continues, unless
the ADC temperature (RT2) is > 150°F (65.6°C) when it
terminates, then the “Secondary Limited ADC” (see be-
low) is initiated.
SYSTEM RUN – SECONDARY LMTD AUTO-DECRYST
(EPROM version A.02F.02 or later; applicable only to
units equipped with Buffalo pumps, Micro Board program
jumper JP2 in)
The unit is running and performing a “Secondary Lim-
ited Automatic Decrystallization Cycle”. The secondary
limited ADC is performed for 15 minutes. It is initiated at
the completion of a “Primary ADC” (see preceding) if
the ADC temperature is > 150°F (65.6°C) when the pri-
mary ADC terminates. While the “Secondary ADC” is in
Summary of Contents for MILLENNIUM YIA-HW-14F3
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