York MILLENNIUM YIA-ST-1A1 User manual

MODELSYIA-ST-1A1THROUGHYIA-ST-14F3(STEAM)
MODELSYIA-HW-1A1THROUGHYIA-HW-14F3 (HOT WATER)
OPERATORS MANUAL
MILLENNIUM
TM CONTROL CENTER
OPERATIONS MANUAL
Supersedes: 155.16-O3 (894) Form 155.16-O3 (797)
ABSORPTION LIQUID CHILLERS
28342A

YORK INTERNATIONAL 1
FORM155.16-O3
TABLE OF CONTENTS
USINGTHIS BOOK............................................................................................... 2
THEORY OF OPERATION
Overview .................................................................................................. 2
Operation.................................................................................................. 3
Dilution...................................................................................................... 9
Purge........................................................................................................ 10
OPERATION FLOW CHART ................................................................................. 11
CONTROL CENTER ............................................................................................. 88
OPERATION
Displaying System Parameters ................................................................. 89
LiBr Concentration Calculator ................................................................... 91
System Setpoints...................................................................................... 91
Displaying System Setpoints .................................................................... 93
PROGRAMMINGTHE ISOFLOW CONTROL CENTER
Programming System Setpoints ............................................................... 94
SERVICE KEYS
Unit Keys .................................................................................................. 98
Other Service Keys................................................................................... 99
OPERATING MODES............................................................................................ 102
UNIT SWITCH....................................................................................................... 103
DISPLAYMESSAGES........................................................................................... 103
Page

2YORK INTERNATIONAL
USING THIS BOOK
The“TheoryofOperation”sectionprovidesan overview
of the unit control provided by the MILLENNIUM CON-
TROL CENTER.Unitcontrol isdescribed andoperating
and status messages that are displayed on the Control
Center display are highlighted.
The “Operation Flow Chart” can be used as a quick
reference of unit control providing safety, cycling and
warning messages and the inputs or thresholds that
produce these shutdowns and messages. Also, the
sequence of events of all safety and cycling shutdowns
and respective reset thresholds are detailed in sepa-
rate flow charts. To use this flow chart, start at the
beginning and read down. The starting sequence is
described, followed by the system parameters that are
monitored (checked) by the Control Center. The Con-
trol Center’s response to each of these checks is de-
scribed adjacent to the check. The Control Center is
programmed to respond in a certain way to each of the
monitored parameters. Pressures and temperatures
that exceed safety thresholds result in a safety shut-
down. Other Control Center inputs that are open or
closed cause safety or cycling shutdowns. If a shut-
down is initiated, the displayed message is shown.The
user is directed to a safety or cycling shutdown flow-
chart that details the sequence of events of the shut-
down and allowable restart thresholds. That flowchart
then returns the user to the main flowchart. Not all
responses cause shutdowns. Some cause the Control
Center to limit operation by shutting down a pump or
inhibit unit loading. These responses are shown adja-
cent to the check along with any warning message.
The “Control Center”and “Operation”section describes
how to operate the Control Center.The functions of the
major grouping of keys are described. It also describes
how to display system parameters such as tempera-
tures and pressures. Finally, each system setpoint is
explained along with how to display the programmed
system setpoints.
Inthe“ProgrammingtheMillenniumControlCenter”sec-
tion, the operator is instructed in how to program sys-
tem setpoints.
The “Service Keys” section describes the function and
operation of the service keys.The service keys are pro-
vided for use by the service technician or operator to
have manual control of certain unit functions.
The “Operating Modes” section describes the various
operating modes and how to change the operating
modes.The“Unit Switch” section describes how to start
and stop the unit.
The “Display Messages” section is a listing of all the
operating, status, safety and cycling shutdown mes-
sages that are displayed on the keypad display. The
meaning of each message is described in detail; in-
cluding the system event threshold that caused the
message to be displayed and the event or threshold
that causes the message to be cleared.
THEORY OF OPERATION
OVERVIEW
An understanding of the operation of a single-stage
absorption chiller requires a review of the chiller’s mi-
cro panel wiring diagram, power panel wiring diagram,
the keypad, and the description which follows. Major
system components include the solution pump (re-
placed by two pumps – absorber and generator on 50
Hz Models YIA-10E3 – YIA-14F3 units equipped with
Franklin pumps– that areindividually controlled);refrig-
erant pump;purge (vacuum) pump and purge solenoid
valve; manual purge valve; steam or hot water control
valve feedback potentiometer and steam or hot water
stop valve; generator shell pressure transducer, strong
solutiontemperaturesensor,high pressureandhigh tem-
peraturecut-out switches;steam supplypressuretrans-
ducer(steamunitsonly);steamor hotwatersupplytem-
perature sensor; automatic decrystallization (ADC)
temperature sensor; refrigerant temperature-sensor;
refrigerant temperature leaving the condenser sensor;
low refrigerant temperature cut-out switch; refrigerant
level float switch (1F); motor coolant level float switch
(2F)(unitsequipped withFranklinpumps only);refriger-
ant level float switch (3F) (units equipped with Buffalo
pumpsonly);chilledand condenser waterflowswitches
(condenserwaterflowswitchfurnished byothers);chilled
andcondenserwaterpumps(byothers);inlet andoutlet
temperaturesensors forchilledandcondenserwatercir-
cuits;refrigerant (unloader) solenoidvalve;stabilizerre-
frigerant solenoid valve; motor coolant solenoid valve
(units equipped with Franklin pumps only); and steam
condensate drain solenoid valve.
An absorption chiller functions by heating a lithium bro-
mide solution to generate hot refrigerant vapor and
strong solution (64.5% lithium bromide).

YORK INTERNATIONAL 3
FORM155.16-O3
Two variations of the ModelYIA units are as follows:
• Models YIA-ST-1A1 thru YIA-ST-14F3 with ADC for
steam applications.
• ModelsYIA-HW-1A1 thruYIA-ST-14F3 with ADC for
hot water applications.
Although two applications exist for Models YIA steam
and hot water units; namely, standard and FAX-4500
versions, both are accomplished through the use of a
singleEPROM. FAX-4500 operationis selectedbyplac-
ing the EMS/MODEM Micro Board jumper in the EMS
positionandselectingREMOTE mode fromthe keypad.
Standard operation is selected by placing the EMS/
MODEM Micro Board jumper in the MODEM position
and selecting LOCAL mode from the keypad. Remote
hard-wired PULSE WIDTH MODULATION (PWM) op-
eration may also be selected by placing the MODEM/
EMS Micro Board jumper in the MODEM position and
selecting REMOTE mode from the keypad.
Units could be equipped with either of two pump types,
depending upon the unit vintage. Units manufactured
before June 1996 are equipped with Franklin pumps*.
After that, units are equipped with Buffalo pumps.
EPROMversionA.02F.02(andlater) support bothtypes
of pumps.Micro Board program jumper JP2 selects the
appropriate control for either pump type: IN – Buffalo
pumps, OUT – Franklin pumps.
Units equipped with Franklin pumps have a Refrigerant
Level Float Switch (1F), a Motor Coolant Float Switch
(2F) and a Motor Coolant SolenoidValve (1SOL).Also,
on 50 Hz ModelsYIA-10E3 thruYIA-14F3 with Franklin
pumps,the Solutionpump isreferredto astheAbsorber
pump; and there is an additional pump called the Gen-
erator pump (4M). Operation is as described below in
“Operation”section.
If the unit is equipped with Buffalo pumps, the Refriger-
antpumpmustbecontrolled differentlythan if theunit is
equipped with Franklin pumps.The Buffalo Refrigerant
pump must not be allowed to run for extended periods
without pumping refrigerant because it is cooled with
refrigerant. Refrigerant Level Float Switches (1F) and
(3F) are used to detect the refrigerant level at the pump
input.Floatswitch1Fislocated above 3F. The pumpwill
not be started until the refrigerant level is sufficient to
cause both 3F and 1F to close.When the level has de-
creased to a level that causes both 1F and 3F to open,
the pump will be shut off. There are certain program-
mablesetpointtimedelaysassociated withtheseevents;
“REFRIGERANT PUMP START-UP DELAY” timer de-
termines the time delay between detection of sufficient
refrigerant level and refrigerant pump start; “REFRIG-
ERANT PUMP SHUTDOWN DELAY” timer determines
thetimedelaybetween detectionof insufficient refriger-
ant level and refrigerant pump shutdown;and REFRIG-
ERANTFLOATSWITCHSHUTDOWN”timerdetermines
the number of minutes the unit is permitted to run with-
outthe refrigerantpumprunning.Ifthistimeisexceeded,
asafety shutdownis performed.These setpointscanbe
changed only by a qualified service technician following
instructions in “Service” manual, Form 155.16-M3.The
Motor Coolant Float Switch (2F), Motor Coolant Sole-
noid Valve (1SOL), and Generator Pump (4M) (50 Hz
Models YIA-10E3 thru YIA-14F3) required for Franklin
pumps are not present.The Solution pump is not called
the Absorber pump on 50 Hz models as with units
equipped with Franklin pumps. Also, the Automatic
Decrystallization Cycle (ADC) is performed differently
than with Franklin pumps.Operation is described below
in“Operation”section.
OPERATION
Whenever power is applied to the micro panel, the fol-
lowingsafetychecksareperformed: generatorshellhigh
pressure and high temperature (analog and digital) cut-
outs;steamsupply pressure(safetyand warningchecks;
steam units only); low refrigerant temperature (analog
anddigital)cut-outs;steamorhotwatersupply tempera-
ture (safety and warning checks); refrigerant tempera-
ture sensor; motor coolant level float switch (units
equipped with Franklin pumps only);solution (absorber
on 50 Hz Models YIA-10E3 – YIA-14F3 with Franklin
pumps),generator (50HzModelsYIA-10E3–YIA-14F3
withFranklinpumps)and refrigerantpumpoverloadsand
thermal switches; all standard customer interface con-
tacts;if tripped, they produce a“SYSTEM SHUTDOWN
PRESS STATUS” message with the appropriate status
message.Both the refrigerant level float switch and the
automaticdecrystallizationtemperaturesensor aremoni-
toredwheneverpoweris appliedto perform controlfunc-
tions. A 10 second lockout delay at power-up prevents
pump chattering if the supply power is intermittent.The
steam or hot water control valve potentiometer, when
open above 10%, prevents unit start by providing a unit
cycling shutdown.Whenever power is applied, the sta-
tusof thepurge pumpmotor overloadsarecheckedand,
if tripped, produce a background message“WARNING:
PURGE PUMP OVERLOADS OPEN”.
Thesteam condensatedrainsolenoidvalve(steam units
only) prevents steam flow through the generator when-
ever the unit is off or whenever a power failure occurs.
This reduces the possibility of unit crystallization. Simi-
larly, on hot water applications, the unit’s installer must
ensurethatthe hotwaterpumpdoes notoperateduring
unit power failures.
Manual operation of the solution (absorber on 50 Hz
Models YIA-10E33 – YIA-14F3 with Franklin pumps)
pump;generator pump (50 Hz ModelsYIA-10E3 –YIA-
14F3 with Franklin pumps); refrigerant pump; purge
pump;chilled water pump, condenser water pump, and

4YORK INTERNATIONAL
manual dilution cycle is controlled via the MANUAL
PUMP key in the Service section of the keypad. The
PUMP STATUS key employs a scrolling feature to allow
control of the pumps, the manual dilution cycle, and the
stabilizer refrigerant solenoid valve via the MANUAL
PUMP key. In SERVICE mode, each pump may be op-
erated manually if not already required to run due to
chiller operation or the dilution cycle; in addition, if the
refrigerant temperature is below 34°F (1.1°C), the solu-
tion pump does not allow manual operation;if a respec-
tive pump’s overloads trip, the manual run signal is ter-
minated.Units equipped with Franklin pumps do not al-
lowmanualoperationof the refrigerant,solution or gen-
eratorpumps whilethemotor coolantfloat switch(2F) is
open, and units equipped with Buffalo pumps do not al-
low manual refrigerant pump operation unless both re-
frigerant level float switches (1F) and (3F) are closed.
Thepumpshallbeonfor2hours (exceptthepurgepump,
which requires manual turnoff) and then automatically
turn off.While the PUMP STATUS keyis usedtodisplay
the message “MANUAL DILUTION CYCLE”, the MAN-
UAL PUMP key (in SERVICE mode only) allows on/off
operation of the manual dilution cycle; with the unit off
and not in the automatic dilution cycle, it initiates a dilu-
tioncycleunless therefrigerantlevel floatswitchis open
or the refrigerant temperature is less than or equal to
34°F (1.1°C). When activated, the solution (absorber
and generator on 50 Hz Models YIA-10E3 – YIA-14F3
withFranklinpumps),refrigerant, chilledand condenser
pumps run until the refrigerant level float switch opens,
the refrigerant temperature falls to 34°F (1.1°C), or 6
minutes has elapsed.To stop the manual dilution cycle
beforeautomatictermination,press theMANUAL PUMP
key again.The stabilizer refrigerant solenoid valve may
be controlled manually in SERVICE mode only via the
MANUAL PUMP key when the PUMP STATUS key is
used to display the “STABILIZER REFRIGERANT SO-
LENOID VALVE ON (OFF)” message and MANUAL
operationhasbeen selectedusingthe MANUAL PUMPS
key via the special access code in PROGRAM mode.
The on/off status for all pumps and solenoids is pro-
videdon theunitprint-out.InLOCAL, REMOTE, orSER-
VICE mode, the MANUAL PUMP key is used in con-
junction with the PUMP STATUS key to control opera-
tion of the PURGE PUMP to allow manual purge opera-
tion.
To initiateastartin LOCAL mode,presstheUNIT switch
on the keypad.If the steam or hot water control valve is
open less than 10% and the leaving chilled water tem-
perature is at or above setpoint, the panel displays the
message “COOLING START SEQUENCE INITIATED”
and the chilled water pump contacts close.The chilled
water and condenser flow switches are bypassed for 30
secondseachafter therespectivepumpis turned on,or
until the respective flow switch closes, if less than 30
seconds. If the unit is kept from starting because the
leaving water temperature is below setpoint, a cycling
shutdown shall be initiated, with the background mes-
sage “WED 2:34PM LVG WATER TEMP BELOW SET-
POINT”. For LWT shutdowns only, the system starting
temperatureis determinedbyadding 2.0°F(1.1°C)to the
leavingchilled watersetpoint.Similarly,the LWTcycling
shutdown occurs when the temperature falls to 2.0°F
(1.1°C) below setpoint or a minimum of 38°F (3.3°C);
when this occurs, the dilution cycle is initiated;following
this, the chilled water pump continues to run, unless the
UNIT switch is placed in STOP/RESET position. If one
or more of the system status checks is negative, the
paneldisplaysthe“SYSTEM SHUTDOWN-PRESS STA-
TUS” message with the appropriate background mes-
sage. If all checks are normal, the chilled water pump
starts immediately. When the chilled water flow switch
closes, the condenser pump is turned on.
If the condenser water flow switch does not close within
30 seconds of the condenser pump turn-on, a cycling
shutdownisperformed.Whenthecondenserflowswitch
closes,thesteam/hotwatershutoff valvesare energized
and if the unit is equipped with Franklin pumps, the re-
frigerant pumpandgenerator pump(50Hz ModelsYIA-
10E3-YIA-14F3)arestarted.Simultaneously,thepanel
displays “SYSTEM RUN-LVG CHILLED WATER CON-
TROL”.
If the unit is equipped with Buffalo pumps, refrigerant
pump operation is controlled by float switches 1F and
3F.The refrigerant pump is not started until both refrig-
erant level float switches 3F and 1F close and the “RE-
FRIGERANT PUMP STARTUP DELAY” setpoint timer
haselapsedas follows:Therefrigerantlevelwill rise toa
level that causes 3F to close. As the level continues to
rise, it will cause 1F to close.When 1F closes, the RE-
FRIGERANT PUMP STARTUP DELAY setpoint timer
(1-900 seconds) is started.If 1F remains closed for the
durationofthetimer,therefrigerantpumpis startedwhen
the programmed delay has elapsed. After the refriger-
ant pump has been started, if the refrigerant level de-
creases to the extent that first 1F opens and then 3F
opens, the REFRIGERANT PUMP SHUTDOWN DE-
LAY setpoint timer (1-45 seconds) is started when 3F
opens.If 3F remains open for the duration of the timer,
the refrigerant pump is shut off after the programmed
delay has elapsed.When the unit first enters SYSTEM
RUN orafter arefrigerantpumpshutdown hasoccurred
due to low refrigerant level, the REFRIGERANT FLOAT
SWITCH SHUTDOWN setpoint timer (20-60 minutes)
is started.The programmed value is the number of min-
utestheunitis allowedtorunwithouttherefrigerantpump
running.If the refrigerant pump is not started before the
timer has elapsed, a safety shutdown is initiated and
“DAY-TIME-REFRIGERANT PUMP FLOAT SW FAIL-
URE” is displayed.To assure that both 1F and 3F float
switches are operational and not stuck in one position,
the program compares the state of 1F to 3F.Since each
float switch closes as the refrigerant level rises against

YORK INTERNATIONAL 5
FORM155.16-O3
it and opens when the level decreases below the float,
and 1F is at a higher level than 3F, it is not possible that
1F would be closed if 3F is still open; unless one of the
switches is stuck in one position.If this condition is de-
tected,asafetyshutdownisperformed and“DAY-TIME-
REFPUMP FLOAT SWCONFLICT”is displayed.NOTE:
the state of each float switch is not recognized as being
valid until it has been in the same position for the dura-
tionofthe respective floatswitch timer.1F isdetermined
by REFRIGERANT PUMP STARTUP DELAY setpoint
timer; 3F is determined by REFRIGERANT PUMP
SHUTDOWN DELAY setpoint timer.Therefore,the float
switch conflict will be allowed to exist for the duration of
the respective timer, depending upon which float switch
is causing the conflict.
Therefrigerantlevelsolenoid (unloadercontrol)valveis
energized (open) whenever the refrigerant level float
switch opens and the leaving water temperature is less
than 5°F (2.8°C) above setpoint. If the refrigerant tem-
peratureis above34.0°F (1.1°C),thesolution (absorber
on 50 Hz Models YIA-10E3 – YIA-14F3 with Franklin
pumps) pump is also turned on.If however, the refriger-
ant temperature falls below 34.0°F (1.1°C), the solution
(absorber on 50 Hz Models YIA-10E3 –YIA-14F3 with
Franklin pumps) pump is turned off and will not turn on
untiltherefrigeranttemperaturehas risenabove35.5°F
(1.9°C). If the refrigerant temperature is above 36.0°F
(2.2°C), the stabilizer refrigerant solenoid valve is de-
energized(closed).Coincidental withtheopening ofthe
steam or hot water stop valve, if selected by the opera-
tor, a softwaretimer isinitiated,limiting the steamor hot
watercontrol valveactuator opening, delaying the auto-
matic temperature-controlled operation of the actuator.
Thisfunctionprevents excessive steamorhot wateruse
duringunitpulldown,allowingtheunittorampuptomatch
theloadoveranadjustable0 to255 minuteinterval.This
feature is called the Pulldown Demand Limiter. At the
conclusion of the pulldown interval or whatever the
pulldown limit is not exceeded, unit loading is controlled
by the automatic temperature control algorithm.
The minimum position of the modulating steam or hot
water valve is programmable from 10-20% valve posi-
tion.Themicropanelvariestheloadbypulsingthe steam
or hot water control valve actuator close and open to
control chiller capacity from the programmed lower limit
(10 - 20%) to 100%.At unit shutdown, the steam or hot
water control valve is driven closed.A potentiometer on
the valve provides position feedback to the micro panel,
whichis displayedon thekeypadviatheDISPLAY DATA
key.System start is only allowed when the steam or hot
water control valve is unloaded below 10%. Steam or
hotwaterunitsare usedfor coolingonly.Allunits canbe
manually controlled (LOAD, UNLOAD, HOLD) in SER-
VICE mode from the keypad. When a unit is commis-
sioned, it is sometimes necessary to limit the maximum
load. This is accomplished by entering the special ac-
cesscode toenter PROGRAMmode.ViatheLOAD key,
the Service Engineer can program the MAXIMUM
COOLING LOAD andfrom 50to100%.Thedefaultvalue
is100%.When theunit isoperating,ifthemaximumload
is reached, the message displayed is “SYSTEM RUN -
MAXIMUM COOLING”.
During operation, the refrigerant temperature sensor,
whichis continuouslymonitored anddisplayed,provides
several control functions. If the refrigerant temperature
fallsto 35.5°F(1.9°C), thestabilizerrefrigerantsolenoid
valve(2SOL)isenergized(open) onunitsequippedwith
Franklinpumps;iftheunitisequipped withBuffalopumps,
it will be energized only if the refrigerant pump is run-
ning. This transfers refrigerant to the generator’s solu-
tion outlet line to reduce the concentration, thus reduc-
ingthecoolingcapacityof theunit.This lessensthe pos-
sibility of crystallization. Simultaneously, the warning
message “LOW REFRIGERANT TEMPERATURE” is
displayed via the STATUS key and unit loading is inhib-
ited.If the temperature falls to 34.0°F (1.1°C), the solu-
tion (absorber on 50 Hz Models YIA-10E3 – YIA-14F3
with Franklin pumps) pump turns off; this should allow
therefrigeranttemperaturetorise.Ifthe refrigerant tem-
peraturerisesto35.5°F(1.9°C),thesolutionpump turns
on.Ifthe refrigeranttemperature risesto36.0°F(2.2°C),
the stabilizer refrigerant solenoid valve is de-energized
(closed), and the unit loading inhibit is removed. How-
ever if the refrigerant temperature continues to fall, a
low refrigerant temperature safety shutdown occurs at
33.0°F (.5°C).If the unit experiences a shutdown when
therefrigeranttemperature is34°F(1.1°C) orbelow, the
chilledwaterpump continuesto runfora minimumof 30
minutes. Subsequently, when the refrigerant tempera-
ture rises to 37.0°F (2.8°C), the dilution cycle begins.
The motor coolant solenoid valve (units with Franklin
pumps only) is energized (open) whenever the strong
solution temperature is above 160°F (71.1°C) (on units
equipped with EPROM version A.02F.02 or later, this
thresholdisprogrammablefrom 127°Fto160°F(52.8to
71.1°C);the threshold should only be programmed by a
qualifiedservicetechnicianfollowinginstructions in“Ser-
vice”manual, Form 155.16-M3).The solenoid is de-en-
ergized (closed) whenever the strong solution tempera-
ture is below 150°F (65.6°C) (on units equipped with
EPROMversionA.02F.02 orlater,the close thresholdis
equal to the programmed open threshold minus 10°F).
The purpose of the valve is to prevent evaporation of
water from the float chamber during unit shutdown or
when the unit operates at low load and low condensing
water temperatures.However, if the refrigerant and so-
lution (absorber and generator on 50 Hz Models YIA-
10E3–YIA-14F3withFranklinpumps) pump motorcool-
antlevelfloat switchopens,theunitlocksout ona safety
shutdown.
Afeaturelimitsthe steamorhotwatercontrolvalveopen-

6YORK INTERNATIONAL
ingto30%wheneverthegeneratorshellpressurethresh-
oldof10.00 PSIAis reached.During thistime,thepanel
displaysthe message“SYSTEMRUN-PRESS STATUS”
andthewarningrelaycontacts areclosed.The STATUS
key displays the warning message “HIGH PRESSURE
OVERRIDE”.This feature allows the chilled water tem-
peraturecontrol tobebypassedinorder tokeeptheunit
from cycling off.The warning relay contacts open when
the WARNING RESET key is pressed in LOCAL, RE-
MOTE or SERVICE mode; the message clears only if
the pressure falls to 6.00 PSIA (41.4 kPa) and subse-
quentlythe WARNINGRESET key isdepressedinSER-
VICE mode.If the generator shell pressure continues to
rise, however, the unit shall perform a safety via the HP
cut-out switch at the preset value and, display the mes-
sage “SYSTEM SHUTDOWN-DILUTION-PRESS STA-
TUS”.The background message shall read “DAY-TIME
GENSHELL HIGHPRESS-DIG”.Ananalogbackupcut-
out has also been put in place should the HP cut-out
switch fail. If the switch should fail, the analog HP cut-
out (triggered at generator shell pressure >15.00 PSIA
(103.4 kPa)) would cause the unit to perform a safety
shutdown and dilution cycle.The background message
shallread“DAY-TIMEGENSHELLHIGHPRESS-ANA”.
Whenever the unit shuts down, the steam or hot water
controlvalveand steam orhotwaterwaterstop valveare
de-energized.After completion of the dilution cycle, the
message shall read “SYSTEM SHUTDOWN-PRESS
STATUS”. When the pressure falls to the reset value,
with all other safety and cycling checks satisfied, the
chiller canbe manually restarted after pressingthe UNIT
switchtoSTOP/RESET.
WhentheADC temperaturerises to160°F(71.1°C), the
steam or hot water flow to the unit is reduced to 50% for
a minimum of 10 minutes.Simultaneously, the stabilizer
refrigerant valve is energized for two minutes, transfer-
ring refrigerant to the generator’s drain line and thus to
the shell side of the heat exchanger to dilute the solu-
tion;during the 10 minute cycle, the displayed message
is“SYSTEMRUN-AUTOMATICDECRYSTALLIZATION”.
After 10 minutes, if the ADC temperature falls to 150°F
(65.6°C), the cycle terminates; otherwise, the cycle re-
peats itself.It must be noted that the ADC operation will
continue for at least 10 minutes regardless of a shut-
downorsubsequentrestart.Manualoperationofthesta-
bilizer refrigerant solenoid valve may be selected by us-
ing the MANUAL PUMP key in PROGRAM mode via
thespecialaccess code.Whenselected, manualopera-
tion of the stabilizer solenoid valve is controlled inSER-
VICE mode using the MANUAL PUMPS key.The ADC
temperature is displayed via the DISPLAY DATA key.
On units equipped with Buffalo pumps, if the refrigerant
pump is not running (due to low refrigerant level) when
an AUTOMATIC DECRYSTALLIZATION CYCLE (ADC)
is initiated or if the pump is turned off during an ADC
(due to low refrigerant level), The normal ADC is not
performed.Instead,a“LIMITED ADC”is performed.The
limited ADC has two phases;PRIMARY and SECOND-
ARY. The PRIMARY LIMITED ADC is the same as a
normal ADC except it is performed for 10 minutes only
and the STABILIZER REFRIGERANT SOLENOID
VALVE (2SOL)is notenergized (opened)duringthefirst
two minutes of the cycle, as would be done in a normal
ADC.If aPrimaryADCis initiatedduringa normalADC,
itwillbe performed forthetime remainingonthe normal
ADC timer.“SYSTEM RUN-PRIMARY LIMITED AUTO-
DECRYST”is displayed.Ifrefrigerantlevel floatswitches
1F and 3F close to start the refrigerant pump before the
PRIMARY limited ADC terminates, a normal ADC is
performed for the time remaining on the 10 minute pri-
marylimited ADC timer(the StabilizerRefrigerantSole-
noid Valve 2SOL is energized for the first 2 minutes of
the of the remaining time).Otherwise, when 10 minutes
have elapsed and the PRIMARY LIMITED ADC termi-
nates,normalchilleroperationcontinues,unless theADC
temperature (RT2) is > 150°F (65.6°C) when it termi-
nates,thentheSECONDARYLIMITED ADCis initiated.
The SECONDARY LIMITED ADC is performed for 15
minutes. While it is in effect, the Stabilizer Refrigerant
Solenoid Valve (2SOL) is not energized (opened) and
steam/hot water valve is driven to the closed (0%) posi-
tion. “SYSTEM RUN-SECONDARY LMTD AUTO-
DECRYST”is displayed.Ifrefrigerantlevel floatswitches
1F and 3F close to start the refrigerant pump before the
SECONDARYlimitedADCterminates,aNORMALADC
isperformed (upto maximumof 10minutes)forthe time
remainingon the15 minutesecondarylimitedADCtimer
(theStabilizerRefrigerantSolenoidValve2SOL is ener-
gized for the first 2 minutes of the remaining time) and
the unit continues to run.Otherwise, a safety shutdown
is performed and “DAY-TIME-RFS-CHK FOR CRY-
STALIZATION” is displayed. (RFS = Refrigerant Float
Switch.)
If the refrigerant level float switch opens and the leaving
chilledwater temperatureis lessthan5°F (2.8°C)above
setpoint,therefrigerant levelsolenoid (unloadercontrol)
valve is energized (open) to transfer solution from the
solution (absorber on 50 Hz Models YIA-10E3 – YIA-
14F3 with Franklin pumps) pump discharge to the re-
frigerant pump suction when a low level of refrigerant
wouldotherwise causerefrigerantpump cavitation.This
occursatlight loadswith lowcondenserwatertempera-
tures.Therefrigerantlevel solenoidvalveisinhibitedfrom
openingwheneverthe leavingchilled watertemperature
is greater than or equal to 5°F (2.8°C) above setpoint.
The status of the refrigerant level float switch (open or
closed) and the panel’s control signal to the refrigerant
level solenoid (unloader control) (open or closed) is dis-
playedviathe DISPLAY DATA key.Manualoperation of
the unloader control solenoid may be accomplished in
SERVICE mode via the special access code using the
DISPLAY DATA key in PROGRAM mode. Note that

YORK INTERNATIONAL 7
FORM155.16-O3
manualoperationofthe refrigerantlevelsolenoidis only
allowedin MANUAL PUMPS keyvia thespecialaccess
code in the PROGRAM MODE. If the refrigerant level
solenoidis manuallyenergized(open), itisde-energized
(closed) as follows:
• Manually, using the DISPLAY DATA key
• Automatically,ifthemodeis changedforSERVICE to
LOCAL or REMOTE
Whenever the refrigerant level float switch is open, the
dilution cycle is inhibited or terminated.
Whenever the panel is placed in MANUAL SOLENOID
OPERATION in SERVICE mode through the use of the
MANUAL PUMPS key via the special access code in
PROGRAM mode, both the refrigerant solenoid valve
and the stabilizer refrigerant solenoid valve fall under
manual control. With the exception of the automatic
decrystallization routine, neither pump will respond to
any automatic control while manual control is active. If
the automatic decrystallization routine become active,
the refrigerant stabilizer solenoid valve is reverted from
manual control back to automatic control for as long as
the decrystallization, routine is active.At the end of the
automaticdecrystallization, therefrigerantstabilizerso-
lenoid, if previously in MANUAL mode, will once again
fall under manual operation. When automatic solenoid
operation is selected using the same procedure de-
scribed above, manual control of the refrigerant level
solenoid valve is inhibited and only automatic controls
will affect the operation of the valves. Upon exit form
SERVICE mode, if the valves are in MANUAL OPERA-
TION mode, they will automatically switch to automatic
solenoid control operation.
When the unit is running, there are two different fea-
tures designed to prevent crystallization; if unit is
equipped with EPROM version A.02F.00, the STRONG
SOLUTION TEMP CONTROL is used. If the unit is
equipped with EPROM version A.02F.01 or later, this is
replaced by “LOW ENTERING CONDENSER WATER
TEMP LOAD LIMIT”.
WhentheunitisequippedwithEPROMversionA.02F.00,
three temperatures are monitored to perform STRONG
SOLUTIONTEMP CONTROL as follows:
• Refrigerant Temperature Leaving the Condenser
(RTLC)
• StrongSolutionTemperature
• Leaving ChilledWaterTemperature (LCWT)
The first two sensor temperatures are displayed via the
REFRIGERANT / SOL’NTEMPS keys using a scrolling
technique. Whenever the RTLC is between 72°F and
117°F(22.2°C and47.2°C), thestrong solutiontempera-
ture shall not exceed the values listed following:
For RTLC values between 72°F and 117°F (22.2°C and
47.2°C), but not listed in the table, the corresponding
maximum strong solution temperature is interpolated.If
the strong solution temperature exceeds the allowable
limit, steam or hot water control valve loading is inhib-
itedand theRTLC/strongsolution temperaturealgorithm
is enabled to slowly pulse the valve closed (based on
the table below) until the strong solution temperature is
less than or equal to the limit. However, if the leaving
chilled water temperature is less than or equal to the
setpoint, the steam or hot water control valve is closed
in accordance with the LCWT automatic temperature
controlalgorithm.Wheneverthe RTLClimitsloading, the
displayed message is “SYSTEM RUN - STRONG SO-
LUTIONTEMP CONTROL”.When theRTLClimits load-
ing,ifsubsequentlytheRTLCcheckdetermines thatthe
specified temperature is 1.0°F (.6°C) below the maxi-
mum, the message is replaced with “SYSTEM RUN -
LVG CHILLED WATER CONTROL”, and the automatic
temperature control algorithm is in effect.
If the unit is equipped with EPROM version A.02F.01,
theSTRONG SOLUTION TEMP CONTROL isreplaced
by LOW ENTERING CONDENSER WATER TEMP
LOAD LIMIT.Aftera30minutebypassatunitstart,when-
everthe enteringcondenserwatertemperatureis <74°F
(23.2°C), the maximum allowed steam/hot water valve
position is determined by the valve profile.This profile
includes the valve size, flow characteristics and linear-
ity. These parameters are stored in memory and ac-
cessed based on the YORK part number of the value
used on the unit.This part number is entered by a quali-
fied serviced technician using a procedure in the “Ser-
vice”manual, Form 155.16-M3.While the loading is be-
ing limited due to this condition, “SYSTEM RUN - LOW
ECDWT LIMITIN EFFECT”isdisplayed.Unitsequipped
with EPROM version A.02F.02 and later, in addition to
requiring the entering condenser water temperature to
be<74°F(23.2°C), alsorequire the strongsolution tem-
perature to be > the LOW ECDWT SOLUTION TEMP
OVERRIDE setpoint to perform this load limit. This
setpoint is entered by a qualified service technician us-
ing a procedure in “Service” manual, Form 155.16-M3.
An upper limit on entering condenser water tempera-
VALVE PULSE INTERVAL
TYPE DURATION BETWEEN PULSES
BUTTERFLY 1 second 15 seconds
CAGE/GLOBE 2 seconds 60 seconds
Maximum Refrigerant
Temperature Leaving (°F) 72 97 104 117
the Condenser (RTLC) (°C) 22.2 36.1 40 47.2
Strong Solution (°F) 170 205 214 231
Temperature (°C) 76.7 96.1 101.1 110.6

8YORK INTERNATIONAL
ture provides a warning message and limits the maxi-
mum load to 60% of the steam or hot water valve posi-
tion.The feature, which is bypassed for the first 30 min-
utesofunit operation,is ineffectwhenthe enteringcon-
denser water temperature exceeds the specified limit
for 10 minutes continuously. The maximum allowable
entering condenser water temperature for full load op-
eration is programmable from 75°F to 125°F (23.9°C to
51.7°C).Toprogramthevalue,theService Engineermust
enter the special access code and then PROGRAM
mode. Press the CONDWATERTEMPS key and enter
the desired maximum entering condenser water tem-
perature for which 100% load is allowable.The default
value is 86°F (30°C).
Pull down demand limiting is a standard feature for all
units. In PROGRAM mode, this function allows selec-
tionofthedurationof thedemandlimitinterval,thestart-
ing maximum steam or hot water valve position signal,
andtheending maximumsteam orhotwatervalveposi-
tionsignal.The programmablerange isfrom 20to100%
for steam or hot water units; the allowable duration is
from 0 to 255 minutes. Operation of this function is as
follows: Each time the unit starts, a timer begins count-
ing down the pull down interval.Unit loading/unloading,
controlled by the automatic temperature control algo-
rithm, is initially limited by the maximum programmed
start value.For the remainder of the interval, the limit is
thevaluedeterminedbythe differencebetweenthestart-
ing and ending values multiplied by the time since start-
ing divided by the total time interval selected.Thus, the
actual limit linearly increases from start to end, allowing
the unit to ramp load to limit steam or hot water input.
During thepull downinterval,pressing thePULL DOWN
DEMAND key displaysthe actualload limit andthe time
remaining until timeout.
All steam/hot water valve loading limits (strong solution
temp control, low entering condenser water temp limit,
automatic decrystallization limit, pulldown limit, remote
load limit, maximum load limit), when active, will auto-
matically be scrolled on the display one after another
should two or more be in effect simultaneously. For ex-
ample, if the automatic decrystallization limiting is in ef-
fectand thesteam/hot watervalve isabovethepulldown
limit, the display will flash between the following two
messages so long as the two limits are in effect: SYS-
TEM RUN-AUTOMATIC DECRYSTALLIZATION, and
SYSTEM RUN-PULL DOWN LIMIT.
Unitswith YORK’s optionalIntegrated SystemsNetwork
allow remote start/stop, remote reset of leaving chilled
temperature, and remote steam or hot water limiting.In
addition, all unit information that is displayed on the mi-
cro panel is transmitted to the FAX. Whenever the re-
mote load limit function inhibits the automatic tempera-
ture control operation, the message “SYSTEM RUN-
LEAVINGCHILLEDWATERCONTROL” is replacedwith
the message “SYSTEM RUN REMOTE LOAD LIMIT”.
Unitinstallations whereit isdesiredtocommunicatewith
an existing building automation system or a DDC con-
troller can be accommodated by employing theTransla-
tor.
Steamandhot waterunits havea feature whichallowsa
remote hard-wired input signal on relay board terminals
82 and 1 to provide a remote steam or hot water limit
function.The standardsignal accepted bythepanel isa
1-11secondPWM signalwhich allowsthe limittobe set
from the programmable lower valve limit of 10 - 20% to
100% of the steam or hot water valve position.With the
optional card file and reset card, the signal can be 4-
20mA, 0-10VDC, or a discrete contact closure. If the
remote steam or hot water limit function inhibits the au-
tomatic leaving chilled water temperature control algo-
rithm,themessage“SYSTEMRUN-LEAVINGCHILLED
WATER CONTROL” is replaced with “SYSTEM RUN-
REMOTE LOAD LIMIT”.
When the HISTORY PRINT key is pressed without a
printer connected to the panel the last four causes of
safety or cycling shutdowns and the date and time of
eachare scrolledin alast in,firstoutformat.Uponpress-
ing the HISTORY PRINT key, each shutdown message
may be scrolled manually via the ADVANCE DAY/
SCROLL key. Pressing the ADVANCE DAY/SCROLL
key repeatedly or any other Display key (including the
CANCEL key)exitstheHISTORYdisplay.Thestandard
print-out also includes this information.
The absorption chiller can display and print messages
in either English or German. Jumper J12 on the I/O Ex-
pansion Board determines which language is displayed
and printed. If J12 is installed, English messages will
appear, otherwiseifJ12isremoved,German messages
will be active.
The software is also equipped with a concentration cal-
culator routine.This routine allows a serviceman to de-
termine what the concentration level of the solution is at
any time. Access to the calculator routine is gained by
pressing the OPTIONS key in PROGRAM mode.
Iftheunit isequippedwith EPROMversion A.02F.02 (or
later), the solution concentration is automatically calcu-
lated using the strong solution temperature (as sensed
bythermistorRT3)and therefrigerant temperatureleav-
ing the condenser (as sensed by thermistor RT9).Con-
centrations between 40% and 70% will be displayed.
Concentrations outside of this range will be displayed
as “> 70%” or “< 40%”. The solution concentration is
displayed as one of the scrolled messages using the
REFRIGERANT/SOLUTION TEMPS key.

YORK INTERNATIONAL 9
FORM155.16-O3
DILUTION
The dilution cycle occurs at most shutdowns.The dilu-
tion cycle is required to prevent crystallization of the
lithium bromide solution. During the dilution cycle, the
solution (absorber and generator on 50 Hz ModelsYIA-
10E3 –YIA-14F3 with Franklin pumps);refrigerant;and
chilled and condenser water pumps are on and a 6
minute timer is initialized. Normally, the dilution cycle
terminates via the 6 minute timer. However, if the re-
frigerant level float switch is open,the dilution cycle
isterminated immediately;if therefrigerant tempera-
ture is less than or equal to 34°F (1.1°C), the dilution
cycle is terminated.If the chiller is shut down due to
the solution (absorber or generator on 50 Hz Mod-
elsYIA-10E3 –YIA-14F3 with Franklin pumps) or re-
frigerant pump overloads or thermal switches, the
condenser water flow switch, the refrigerant tem-
perature sensor or cut-out switch,the chilled water
flow switch, or the motor coolant level float switch,
thedilution cycleshall beby-passed.Openingof any
of the previously listed contacts (in bold type) dur-
ingthe dilutioncyclealso disablesthe dilutioncycle.
If the solution (absorber or generator on 50 Hz Models
YIA-10E3–YIA-14Swith Franklinpumps) orrefrigerant
thermal switches reclose, the dilution cycle is initiated
(onetimeonly)ifthe strongsolutiontemperature isabove
136°F(57.8°C).However, ifthe strongsolution tempera-
ture falls to <136°F (57.8°C) and the dilution cycle has
not begun, or if the overload contacts close a second
time, the unit shall initiate a safety shutdown with the
background message “TUE 9:47AM-PO-CHK FOR
CRYSTALLIZATION”. After decrystallization, if neces-
sary, theunit canbe restartedbydepressing theWARN-
ING RESET key in SERVICE mode.Either a power fail-
ure,unit start, or “CHKFORCRYSTALLIZATION”mes-
sage clears the dilution cycle counter.
Ifthecondenser waterflowswitch is openforat least30
seconds while the system is running or during a dilution
cycle, the unit will shut down on a condenser water flow
switch failure. If the UNIT switch is in RUN position, the
start sequence is initiated if the switch recloses and the
strong solution temperature is above 136°F (57.8°C); if
theUNIT switch isin STOP/RESET position,the dilution
cycle is initiated.If the strong solution temperature falls
to <136°F (57.8°C), however and the condenser water
flow switch is open, the unit shall initiate a safety shut-
down with the background message “TUE 9:47AM
CDFL-CHKFORCRYSTALLIZATION”.Afterdecrystalli-
zation, if necessary, the unit can be restarted by de-
pressingtheWARNING RESET key in SERVICE mode.
If the unit is shut down due to the low refrigerant tem-
perature cut-out at 33.0°F (.5°C) (provided by the low
refrigeranttemperatureswitchorsensor), thechilled wa-
ter pump shall continue to run for a minimum of 30 min-
utes.The dilutioncycleshall beinitiatediftherefrigerant
temperaturerisesto37.0°F (2.8°C)and thestrongsolu-
tion temperature is above 136°F (57.8°C). If the strong
solution temperature falls to <136°F (57.8°C), and the
dilutioncycle hasnotbegun,theunit shallinitiateasafety
shutdown; the background message shall be “WED
2:34PM-LRT-CHK FOR CRYSTALLIZATION”. After
decrystallization, if necessary, the unit can be restarted
by depressing the WARNING RESET key in SERVICE
mode.
Following a chilled water flow switch failure and subse-
quentunitsafetyshutdown, thechilled waterpump con-
tinues to run for a minimum of 30 minutes.If the chilled
waterflowswitch recloseswhilethestrongsolution tem-
peratureis above 136°F(57.8°C), thedilution cycleshall
begin. If however, the strong solution temperature falls
to <136°F (57.8°C) with the chilled water flow switch
open,thedilutioncycleis bypassedand thebackground
message is “WED 2:34PM-FLS-CHK FOR CRYSTAL-
LIZATION”.After decrystallization, if necessary, the unit
can be restarted by depressing the WARNING RESET
key in SERVICE mode.
Following a power failure, if the unit had not previously
completedthe dilutioncycle andthestrongsolutiontem-
perature is above 136°F (57.8°C) and the unit is config-
ured for manual restart after power failure (via removal
ofMicroBoard jumperJ50), theunitshall beginthe dilu-
tion cycle. However, if the strong solution temperature
falls to <136°F (57.8°C), and the dilution cycle has not
begun, the unit shall initiate a safety shutdown in which
the background message is “WED 2:34PM-PF-CHK
FORCRYSTALLIZATION”.Afterdecrystallization,if nec-
essary, the unit can be restarted by depressing the
WARNING RESET key in SERVICE mode.If the unit is
configured for auto restart after power failure (via inser-
tion of Micro Board jumper J50), the dilution cycle shall
be bypassed and a system start will occur.
If the unit is equipped with EPROM version A.02F.00,
followinga motorcoolantfloat switchsafetyshutdown, if
the float switch recloses while the strong solution tem-
perature is above 136°F (57.8°C), the unit shall begin
the dilution cycle. However, if the strong solution tem-
perature falls to <136°F (57.8°C) before the switch
recloses, the unit shall initiate a safety shutdown with
the background message “WED 2:34PM-MCFL-CHK
FORCRYSTALLIZATION”.Afterdecrystallization,if nec-
essary, the unit can be restarted by depressing the
WARNING RESET key in SERVICE mode. If unit is
equipped with EPROM version A.02F.01 or later, a dilu-
tioncycleis notresumed when themotor coolantswitch
closes.
On units equipped with Buffalo pumps, the “REFRIG-
ERANT PUMP STARTUP DELAY” setpoint timer is dis-

10 YORK INTERNATIONAL
abled at the instant of unit shutdown. This allows the
refrigerant pump to start at the beginning of the dilution
cycle without any delay.
PURGE
Since absorption chillers operate at pressures below
atmospheric,apurge systemisrequired toremovesys-
tem impurities which degrade performance and cause
internal corrosion. The system employs a purge pump
motorandpurgesolenoidvalve(wiredinparallel),which
are manually controlled by the operator from the micro
panel keypad, and a manual purge valve (piped in se-
ries).Onatypicalsystem,aminimumofonepurgecycle
is recommended each week. To initiate a purge cycle,
depress the PUMP STATUS key until PURGE PUMP
OFF is displayed;immediately, depress the HOLD key.
WhentheMANUAL PUMP keyisdepressedinLOCAL,
REMOTE, or SERVICE mode with the purge pump off,
the pump runs, the purge solenoid valve is energized
(opened), and the display indicates PURGE PUMP ON.
After the pump runs for about 20 minutes and the suc-
tion pressure as measured on a field-supplied manom-
eter falls to 1.6 mm of Hg absolute (0.03 PSIA), the op-
erator opens the manual purge valve while the pump
continues to run. AFTER about 30 minutes, the purge
cycleiscomplete and themanual purge valve isclosed.
Although the purge cycle is complete, the pump and
solenoid valve are energized for an additional 30 min-
utes or until the suction pressure falls to 1.6 mm of Hg
(0.03 PSIA).The pump and solenoid valve are then de-
energized by depressing the MANUAL PUMP key a
second time,This allows the pump to clean its oil to ex-
tend pump life.After the purge pump runs for at least 10
minutescontinuously,the7dayand theunitlifetimepurge
counters(displayedviathePURGE CYCLE COUNTER
key) increment by 1 count when the pump turns off.
The PURGE PUMP SERVICE INTERVAL key in the
Setpoints area of the keypad allows the operator to
select an appropriate interval for servicing the purge
pump.In PROGRAM mode,the keyallowsa cumulative
purgepumpoperatingintervalfrom5 to100hours tobe
entered.In addition, the display includes the number of
hourstobe entered.Inaddition, thedisplay includesthe
number of hours that the pump has operated since the
last pump service.When the pump operating hours are
greaterthan orequal tothepresetintervalwarning mes-
sage is displayed. After servicing the pump, pressing
the WARNING RESET key in SERVICE mode clears
the message and resets the counter. Moving the CLK
jumperfromOFF toON positionalso clearsthecounter.
The default value for the service interval is 10 hours.

YORK INTERNATIONAL 11
FORM155.16-O3
UNIT OPERATION
LOCAL OR REMOTE MODE
STEAM OR HOTWATER UNITS
BEGIN
LOCAL
OR REMOTE
START
1
2
➤
➤
➤
➤
LVG
WATER TEMP <
SETPOINT
CYCLING SHUTDOWN-
DISPLAY “DAY-TIME-LVG
WATER TEMP < SETPOINT”
AS STATUS
➤
NO
YES
YES
NO
9
PAGE 43
➤
CYCLING SHUTDOWN-
DISPLAY “DAY-TIME-
STEAM/HOT WATER
VALVE LOADED ABOVE
10%” AS STATUS
STEAM/
HOT WATER
VALVE POS.
> 10%
➤
YES
NO
10
➤
PAGE 43
CLOSE CHILLED WATER
PUMP CONTACTS
TB4-44/45
DISPLAY “COOLING
START SEQUENCE
INITIATED”
➤➤
A

12 YORK INTERNATIONAL
START
30 SECOND TIMER
CLEAR
30 SECOND TIMER
CHILLED
WATER FLOW
SWITCH
CLOSED
30 SECOND
TIMER
ELAPSED
SAFETY
SHUTDOWN-
DISPLAY “DAY-
TIME-CHILLED
WATER FLOW
SWITCH” AS
STATUS
CLEAR
30 SECOND TIMER
START
30 SECOND TIMER
CLOSE CONDENSER
WATER PUMP
CONTACTS TB4-55/56
CONDENSER
WATER FLOW
SWITCH
CLOSED
30 SECOND
TIMER
ELAPSED
CYCLING
SHUTDOWN-
DISPLAY “DAY-
TIME-CONDENSER
FLOW SWITCH-
AUTOSTART” AS
STATUS
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤➤
➤➤
➤
➤
➤
12
11
PAGE 45
PAGE 44
NO
YES
NO
NO
NO YES
YES
YES
A
A

YORK INTERNATIONAL 13
FORM155.16-O3
DISPLAY “SYSTEM
RUN-LEAVING
CHILLED WATER
CONTROL
REFRIG
TEMP >34°F
(1.1°C)
START SOLUTION PUMP (1M),
ABSORBER PUMP (50 HZ
MODELS YIA-10E3 – YIA-14F3
WITH FRANKLIN PUMPS)
ENERGIZE 1R RELAY
TO OPEN STEAM/HOT
WATER SHUTOFF VALVE
STEAM
UNIT
ENERGIZE 6SOL
TO OPEN STEAM
CONDENSATE
DRAIN VALVE
BUFFALO
PUMPS
START REFRIGERANT PUMP (2M)
AND GENERATOR PUMP (4M)
(50 HZ MODELSYIA-10E3 –YIA-14F3)
START REFRIGERANT
FLOAT SWITCH
SHUTDOWN SETPOINT
TIMER (20 - 60 MIN)
➤➤➤➤➤➤ ➤
➤
➤
➤
➤
➤
NO
NO
NO
YES
YES
YES
➤
A
AB

14 YORK INTERNATIONAL
FLOAT
SW 3F
CLOSED
FLOAT
SW 1F
CLOSED
REFRIG
PUMP (1F)
START-UP DELAY
TIMER
ELAPSED
START
REFRIGERANT
PUMP (2M)
REFRIG
PUMP (2M)
RUNNING
REFRIG
FLOAT SW
SHUTDOWN
TIMER
ELAPSED
SAFETY SHUTDOWN –
DISPLAY “DAY-TIME-
REFRIGERANT PUMP
FLOAT SW FAILURE”
AS STATUS
FLOAT
SW 3F
CLOSED
FLOAT
SW 1F
CLOSED
START REFRIG PUMP
START-UP DELAY SET-
POINT TIMER (1-900 SEC)
WHEN 1F CLOSES
START REFRIGERANT PUMP WHEN
“REFRIG PUMP START-UP DELAY
SETPOINT TIMER” (1F) HAS ELAPSED
FLOAT
SW 3F
OPEN
FLOAT
SW 1F
CLOSED
BOTH
REFRIG PUMP
START-UP (1F) AND
SHUTDOWN (3F)
DELAY SETPOINT
TIMERS
ELAPSED
SAFETY
SHUTDOWN –
DISPLAY “DAY-TIME-
REF PUMP FLOAT
SW CONFLICT”
AS STATUS
43 PAGE 87
FLOAT
SW 1F
OPEN
FLOAT
SW 3F
OPEN
START REFRIG PUMP
SHUTDOWN DELAY SETPOINT
TIMER (1-45 SEC)
WHEN 3F OPENS
42
4
PAGE 86
PAGE 35
NO NO NO
NO
NO
NO NO
NO
NO NO
SHUTDOWN REFRIG PUMP WHEN
“REFRIG PUMP SHUTDOWN DELAY-
SETPOINT TIMER” (3F) HAS ELAPSED
YES YES
YES
YES
YES
YES
YES
YES
YES YES YES
NO
NO
➤➤
➤
➤
➤
➤
➤
➤
➤➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤➤ ➤
➤
➤
➤
➤➤➤
AB
A

YORK INTERNATIONAL 15
FORM155.16-O3
PULLDOWN
DEMAND
PROGRAMMED
START PULLDOWN
INTERVAL TIMER
(0-255 MIN)
YES
NO
PULLDOWN
DEMAND
PROGRAMMED
20-100%
PULLDOWN
INTERVAL
ELAPSED
PULLDOWN LOAD LIMIT (%) =
(STOP LIMIT-START LIMIT) T ELAPSED +
TINTERVAL
START
LIMIT
[]
PULLDOWN
LOAD LIMIT >
MAX ALLOWED
LOAD
VALUE
PULLDOWN
LOAD LIMIT >
PWM LOAD
LIMIT
PULLDOWN
LOAD LIMIT <
FAX-4500
LOAD
LIMIT
REMOTE
MODE
UNIT
LOADING =
PULLDOWN
LOAD
LIMIT
DISPLAY “SYSTEM RUN-
PULLDOWN LIMIT”
LIMIT LOADING TO PULLDOWN
DEMAND LIMIT (%) VALUE
YES
YES
YES
YESYES
YES
YES
NO
NO
NO
NO
NO
NO
NO
➤➤
➤
➤
➤➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
YES
A
A

16 YORK INTERNATIONAL
CONTROL PER FAX-4500 LEAVING
WATER TEMP SETPOINT
LIMIT UNIT LOADING TO FAX-4500
LOAD LIMIT (10-20) - 100%
DISPLAY “SYSTEM RUN
REMOTE LOAD LIMIT”
PWM REMOTE LOAD LIMIT (%) =
100- [PW-1(100-LOWER LIMIT)/10]
PWM
LOAD LIMIT
> MAX
ALLOWED
LOADING
VALUE
REMOTE
MODE
FAX-
4500
FAX-4500
LOAD LIMIT
> MAX
ALLOWED
LOADING
VALUE UNIT
LOADING =
FAX-4500
LOAD LIMIT
PWM
REMOTE
LOAD LIMIT
(10-20)-100%
UNIT
LOADING
> PWM
LOAD
LIMIT
LIMIT UNIT LOADING TO PWM
REMOTE LOAD LIMIT (10-20)-100%
DISPLAY “SYSTEM RUN
REMOTE LOAD LIMIT”
°F OFFSET =
(PULSEWIDTH-1) (REMOTE RESET TEMP RANGE)
10
SETPOINT = BASE SETPOINT + °F OFFSET
CONTROL PER BASE
LEAVING WATER TEMP
SETPOINT (40-77°F)
PWM
REMOTE
TEMP
SETPOINT
➤➤➤
➤
➤
➤
➤➤
➤➤
➤➤➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
➤
YES
YES YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
A
A

YORK INTERNATIONAL 17
FORM155.16-O3
CHECK PROGRAMMED
“MAX ALLOWED
LOADING”VALUE
(50-100%)
AT MAX
ALLOWED
LOADING DISPLAY “SYSTEM RUN”
MAXIMUM COOLING
LIMIT LOAD COMMAND
TO MAXIMUM ALLOWED
LOADING (50-100%)
CHECK CONDENSER
WATER FLOW SWITCH
@ TB2-20
OPEN
FOR 30
SECONDS
CYCLING SHUTDOWN
DISPLAY “DAY-TIME-COND
FLOW SWITCH-
AUTOSTART” AS STATUS
COMPARE LEAVING
CHILLED WATER TEMP TO
LEAVING WATER TEMP
SETPOINT
AUTO
SOLENOID
CONTROL
DE-ENERGIZE (CLOSE)
REFRIGERANT LEVEL
SOLENOID VALVE (3SOL)
LCWT
> (SP-2) &
< (SP+5)
REFRIG
LEVEL
FLOAT SW
OPEN
ENERGIZE (OPEN)
REFRIGERANT LEVEL
SOLENOID VALVE (3SOL)
13
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YES
YES
YES
YES YES
NO
NO
NO
NO NO
PAGE 46
A
A

18 YORK INTERNATIONAL
LCWT <
PREVIOUS
SP-2
LCWT
< SP-2
< 30
MINUTES
SINCE LCWT
SP RAISED
LOW WATER TEMP
SHUTDOWN
THRESHOLD = PREVIOUS
SETPOINT-2
CHECK MULTI-UNIT
CYCLING INPUT @ TB2-9
CLOSED
CHECK REMOTE/LOCAL
CYCLING INPUT @ TB2-13
CLOSED
CHECK AUXILIARY
SAFETY SHUTDOWN
INPUT @ TB-31
15
PAGE 49
SAFETY SHUTDOWN-DISPLAY
“DAY-TIME-AUXILIARY SAFETY
SHUTDOWN” AS STATUS
16
PAGE 50
CYCLING SHUTDOWN- DISPLAY
“DAY-TIME-SYSTEM CYCLING
AUTOSTART” AS STATUS
14
PAGE 48
CYCLING SHUTDOWN-DISPLAY
“DAY-TIME-LOWWATER
TEMP-AUTOSTART”
AS STATUS
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YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
A
A

YORK INTERNATIONAL 19
FORM155.16-O3
CHECK LOW REFRIGERANT
TEMP SAFETY CUTOUT @
RELAY BOARD TB3-81
SCHEDULED
FOR SHUTDOWN
CHECK DAILY SCHEDULE
START-STOP TIMES
> 35.5°F
(1.9°C)
SOLUTION
(ABSORBER)
PUMP
RUNNING
CLOSED
18
PAGE 52
CYCLING SHUTDOWN-DISPLAY
“DAY-TIME-INTERNAL CLOCK-
AUTOSTART” AS STATUS
19
SAFETY SHUTDOWN-DISPLAY
“DAY-TIME-LOW REFRIGERANT TEMP
DIGITAL” AS STATUS
PAGE 53
TRIPPED
CHECK REFRIGERANT
TEMP @ RT 8
CYCLING SHUTDOWN-DISPLAY
“DAY-TIME-MULTI-UNIT
CYCLING-AUTOSTART” AS STATUS
17
PAGE 51
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NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
B A
A