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MeQuw@ Installation andMaintenance Data
Bulletin No. IM 552December, 1993Form No. 573899Y
Microprocessor-BasedLeaving Water Control
Model AS-UNT33n-l
This controller is offered as an option on ALR “C vintage and sor-based Leaving Water Controller and accessories contactWHR “D” vintage packaged chillers where control of Leaving SnyderGeneral Corporation for specification sheets for eachWater Temperature is desired. On these units with the control- individual control,Ier factory installed, the control is preset and calibrated and The controller and sensor covered in this installation andshould not need any adjustment other than the control setpoint. maintenance data bulletin are available as substitute replace-
For further information on the AS-UNT33n-l microproces- ments for earlier ALR and WHR units.
Table Of Contents
introduction—AS-UNT33n-l ................................................2
General Description .........................................................2
Standard Control Characteristics .........................................2
AS-UNT33n-l Specifications ... ............................................2
AS-UNT33n-l Accessories ..................................................2
Installation ...........................................................................3
Standards Compliance .....................................................3
Dimensional Data .............................................................4
Mting ...............................................................................5
Operation .............................................................................7
Chiller System ..................................................................7
Leaving Water Temperature Control Operation ...............7
Johnson Controls Leaving Water Sensor ,...........................8
Hone~ell Leaving Water Sensor ........................................8
Additional Features ..............................................................9
Settings and Adjustments ..................................................l O
System Checkout and Troubleshooting .............................10
Features Requiring Factory Configuration ......................... 11
Reset Options ................................................................ll
Zone Terminal User’s Guide ..............................................l3
Introduction ....................................................................l3
Getting Started ..................................................................l4
Making Zone Terminal Adjustments ..................................15
Zone Terminal Glossary ....................................................l6
01993 SnyderGeneral Corporation
IntroductionGeneral Description
The AS-UNT33n-l microprocessor-based leaving water con-trol is designed to control multiple capacity steps of coolin9froma single sensor.
The AS-UNT33n-l operation is based on an adjustablesetpoint and control band as shown in the “operation” sectionof this document. If the Leaving Chilled Water Temperaturebegins to rise to the desired setpoint plus control band/2 (upperlimit), Cooling Stage 1 brings on the first stage of cooling.Additional stages of cooling will follow as long as the LeavingWater Temperature remains above the upper limit of the controlband. As the leaving water temperature begins to drop tosetpoint minus control band/2 (lower limit), cooling stages will
begin to de-energize.There will be no energizing orde-energizing of cooling stages
as long as the leaving water temperature is between the upperand lower limits of the control band.As a rule, anytime the leaving water temperature is above theupper limit of the control band, stages will be energized, andanytime the leaving water temperature falls below the lowerlimit of the control band, stages will be de-energized.At the initial start of the unit a time delay will occur. There is a60-second Interstate On Delay between stages. Each stageincorporates minimum on and off timers with a maximum cyclerate of six cycles per hour.
Standard Control CharacteristicsTable 1: Standard Control Characteristics
I DESCRIPTION
AS-UNT33n-lSETTING
Setpoint Range I 10”F to 60”F (-12-C to +15-C)Adjustable
Control Band Range O-F to 10“F (O-C to 60”)Adjustable
Interstate On Delay BetweenStages 60 seconds
Minimum Off Time (each stage) 5 Minutes
Minimum On Time (each stage) 60 Seconds
Soft Start During Start-up 50% command over 5 minutes
AS-UNT33n-lElectrical Ratings”:Input voltage and frequency (terminals24 VAC-COMMON) 20 to 30 VAC at 50/60 Hz(50 Hz requires download.)Power Consumption:25 VA at 24 VAC and 50/60 HzInput Signal:Honeywell sensor—positive temperature coefficient of 4.8ohms/Degree F; resistance of 3484 ohms at 77”F. JohnsonControls sensor—positive temperature coefficient of 3 ohms/Degree F; resistance of 1000 ohms at 70”F.Number of Stages Selection:Refer to Table 5, Figure 1 for stage selection.Temperature Ranges:Ambient: -40”F to +150°F.
Table 2: Controller Specific Characteristics
CONTROLLER NUMBER OF LEAVING WATER
DESCRIPTION STAGES SENSOR
AS-UNT330-I 4or6 Honeywell
AS-UNT332-I 8 Honeywell
AS-UNT334-1 4or6 Johnson Controls
AS-UNT336-1 8 Johnson Controls
Caution: Offering this control device is not intended to implythat rapid cycling of compressors is condoned by SnyderGeneral.If an application produces rapid cycling, the control and/or theapplication must be reviewed and altered to prevent compres-sor failure.
SpecificationsHumidity Rating:5 to 90% RH noncondensing.Leaving Water Sensor:The Honeywell C7173AIOI 7, Honeywell C7170AI 010, orJohnson Controls TE-6300-300 senses Leaving Water Tem-perature on control terminals A13 and A13 COM.
Table 3: Contact Rating
CONTACT VOLTAGE (V) INRUSH (VA) RUNNING (VA)
N.O. 24 240 60
NC, 24 75 30
NO. 120/240 750 75
NC, 120/240 240 40
AS-UNT33n-l AccessoriesModel No. McQuay Pert No. Quantity Description Application
Johnson TE-6313P-1 070312301 1 Outdoor Air Sensor Used for reset of Leaving Water Setpoint.
Johnson TE-6300-300 070312401 1 Immersion Sensor (30 ft. cord) Senses Leaving or Return Water Temperature
Sensor Well 047441506 1 Immersion Well Used with TE-6300-300
Johnson TE-6410S-200-0 070312801 depends on Zone Temperature Sensor Used for zone temperature reset
#of zones
Johnson AS-ZW330-1 070312701 1 Zone Terminal Used for monitoring and local control of
designated points
Honeywell C7173AI 017 048442405 1 Immersion Sensor (30 ft. cord) Sensing of Leaving Water Temperature
Honeywell C7170AI 010 046442402 1 Immersion Sensor (10 ft. cord) Sensing of Leaving Water Temperature
Honeywell 121 371A 046442403 1 Copper Immersion Well Used with C7173AIO17 or C7170AIOI0
Honeywell 121371E 048442404 1 Stainless Steel Immersion Well Used with C7173AI017 or C7I7OA1OIO
Johnson AS-KITIOO-O 1 Resetor Test Kit Used for field diagnostics.
Page 2 I IM 552
InstallationStandards Compliance
The UNT Controller complies with the following standards:1 ● CSA C22.2 No. 205 ● UL916 ● IEEE 472
● IEEE 446 ● VDE 0871 Class B “ IEEE 587 Category A● IEEE 518 ● FCC Part 15, Subpart A, Class J ● NEMA ICS 2, Part 2-230
All wiring must comply with local codes and ordinances:
1.
2.
3.
4.
5.
6.
Disconnect power supply before making connections toavoid electrical shock and/or equipment damage.
Check ratings given in the specification and on the productto make sure the controller fits the application.
Choose a location for the AS-UNT33n-l controller that isnot exposed to the weather and where controls, connec-tions, and the zone bus phone jack are accessible.
Mount the controller with three No. 8 screws through themounting holes in the base. (See Figure 2,)
Install immersion well and sensor bulb in the LeavingChilled Water piping as instructed by the installation manualfor the unit being controlled.
Connect 24 VAC to terminals marked 24 VAC and COM.CAUTION: Never spark the 24 V power leads to checkfor power.
Table 5: Dipswitch Settings
AS-UNT330-I
AS-UNT334-1
4 stage selection
(set by others)
Oipswitch ettings Factory Stage I Factorv Set ISat Select
AS-UNT 13n-1 Al 1 A12
10 v ●
SW2
2V ●
AS-UNT330-1
AS-U NT334-1
6 stage selection
(set by others)
AS-UNT332-I
AS-UNT336-1
6 stage selection
(set by others)
Swl
SW2
Swl
SW2
Swl
T
v ● ●
10 v ●
2V ●
T ●
v ●
10 v ● ●
2V, I
T I I ●
v I ● I
A13—
—●
�
●
�
—●
●
�
—●
�
●
�
—
A14 A15 A16
● ● ●
● ● ●
● ● ●
● ● ●
● ● ●
● ● ●
Do not run low-voltage wiring in the same conduit as line-voltage wiring (30 VAC or above) or wiring that switchespower to highly inductive loads (such as contractors,coils, motors, or generators).
7. Wire the compressor and capacity controls steps to theindividual controller relay terminals as shown in the unitwiring diagram.
8. Adjust SW1 and SW2 on A12 for the appropriatenumber of cooling stages. The AS-UNT330-l/AS-UNT334-1 is factory set for 6 stages by JohnsonControls. The AS-UNT332-l/AS-UNT336-l is factoryset for 8 stages. Refer. o Table 5 and Figure 1.
L
Figure 1: Analog Input Switches
wArdog Inputswitches
IM 552 I Page 3
Dimensional Data
Figure 2: Dimensional DataI
—
—
+mrL3L-,Iuiuullin’u”i: II~lll_l I ‘1,0
II I&p--’1
L
5.80 1.24
r 1-
-
@
1
..
eF
1- -1
~ = mounting holes
A 7il
*I
—
mLy0)
—
o“ I
Page4/ IM 552
I
Wiring
Figure 3: Wiring Diagram
DEMAND LIMIT*(1) 0-10 VDC
(+)
25 (-)—Al CM A12
LEAVING
A= T ,
SHUTDOWN*
00Al CM A16 h
~~ p+15VDC +15VDC G
(2)
—— I
COMP LEADILAG*24VAC BI1
B14 ~
FLOW INTERLOCKI g;— g;. ;
* Indicates 18z
optional 512/518
~ ❑ :feature. 24VAC
28 )
n 519 + #
(1) Sensor for Outdoor, Return Water, or Zone Temperature Reset options are connected to Al-1 and Al-CM.
(2) Field connections must be made betweenTB3-18 and BI-4 for unit to operate.
Figure 4: Stage Relay Configuration
Note: Refer to Unit WiringDiagram for StageWiring.
IM 552/ Page 5
Table 6: Wiring Location Cross Reference
Lead # H~Y# Stages Johnson Controls (JCI)AS-UNT33n-l
512 TB3-18 to TB3-29 (4,6,8, Stages) Not Needed (See Note 0 and@)
518 Tb3-29 to “TR” “ TB3-18 to 24 VAC
519 “TR” “ Common
522 Ground “ Not Needed
524 “7” “ Not Needad (See Note@)
525 TB3-23 to TB3-24 “ Not Needed
526 “6” “ Not Needed (see Note 0)
527 “P” to “Pi” “ Not Needed or Zone TerminalAdjust
528 “1-” “ AI-3 (JCI or HN Leaving WaterSensor. See appropriate
sensor section)
529 “Tl” “ AI-CM (JCI or HANLeaving WaterSensor. See appropriate
sensor section)
400 OHM “7” to “6”Resister
4 Stages
600 OHM “7” to “e”Resister
6 Stages See Table 5
600 OHM “7” to “e” 8 StagesResister523 Ground 8 Stages Not Needed
535 . .1 ,, Not Needed
536 “2” ,, Not Needed
537 “.3 ,, Not Needed
538 “.4 “ Not Needed
Notes:@ To install Flow Switch Contacts, connect between TB3-18 and UNT BI-4.@ To install Time Clock Contacts. connect between TB3-18 and UNT B1-1.~ The options areas follows. (Option A is standard; options B, C, and D require field download, See
“Features Requiring Configuration and/or Field Adjustment” section for more information):A. The standard is Demand Limit Input. O-1OVDC signal is required. Connect leads to
Al-1 and Al-CM on the controller.B. Johnson Controls Outdoor Air Sensor if Outdoor Air Reset is used.C. Johnson Controls Zone Temperature Sensor if Zone Temperature Reset is used.D. Johnson Controls Return Water Sensor if Return Water Reset is used.
Page 6/ IM 552
OperationChiller System
Chiller systems are used to provide cold water for comfort Figure5: Chiller Systemcooling or process applications. Control of the compressoroperation to supply that cold water maybe initiated by sensingReturn Water Temperature or Leaving Water Temperature. Ifprecise control of Leaving Water Temperature is desired a AS-UNT33n-1 controller is recommended.
I I CONTROL JRESET
(optional)
LEAVINGWATER
SENSORw=ENsOR ‘UMP
I ICOOLING LOAD
Leaving Water Temperature Control Operation
Leaving Water Temperature will be controlled to the ActualLeaving Water Setpoint. The Actual Leaving Water Setpoint willbe a function of what mode of operation the controller is in andif a reset option is used. The Control Band potentiometer locatedon the front of the controller is used to determine the ActualLeaving Dead Band and Prop Band.
Actual Leaving Dead Band: Control Band (A16)/2.
Actual Leaving Prop Band: Dead Band * Number of Stages.
Example:Control Band = 4 Deg FNumber of Stages = 6Dead Band. 4/2 = 2 Deg FProp Band= 2*6=12 Deg F
As the Leaving Water Temperature rises above the ActualLeaving Water Setpoint, but within the Leaving Dead Band,there will be no increase in the Compressor Command. As theLeaving Water Temperature continues to rise above the DeadBand and into the Prop Band, the Compressor Command will beincreased. When Leaving Integration Gain is used, a Propor-tional Plus Integral command will be calculated. As the Com-pressor Command increases, stages of cooling capacity will beenergized. Minimum on, off, interstage times, and cycles perhour attributes will control the stages.
As the Leaving Water Temperature decreases towards theActual Leaving Water Setpoint, the Compressor Command willbe decreased. Upon reentering the Dead Band, the currentCompressor Command will be maintained. If the Leaving WaterTemperature falls below the Actual Leaving Water Setpoint(using the same Dead Band), the Compressor Command willagain start to decrease.
The “Control Band” is the non-staging area of the control.Anytime the Leaving Water Temperature is outside of the control
Figure 6: AS-UNT33n-l Leaving Water Control Algorithm Operation
l\
Jband limits, staging will occur. Anytime the Leaving WaterTemperature is within the control band limits, no staging occurs.As shown in Figure 6, with a 45°F setpoint and a 4°F control bandsetting, stages of cooling energize when the Leaving Water is47°F or higher. Stages de-energize when the Leaving Water is43°F or lower (4°F difference). All stages will remain in theircurrent state between 43°F and 47°F.
AS-UNT33n-l LED OPERATIONThe AS-U NT33n-l has one LED for each staged output. TheLED on the AS-UNT33n-l will light simultaneously as thatstage relay energizes. If the LED is not lit, the stage is notenergized. When a stage relay energizes, the normallyclosed contacts open, and the normally open contacts close,
IM 552/ Page 7
Johnson Controls Leaving Water Sensor
Note: Johnson Controls or Honeywell Leaving WaterSensors may be used with the AS-UNT33n-l. Refer to Table2, page 2. A description of the Honeywell sensor follows thedescription of the Johnson Controls sensor.
Table 7: Johnson Controls Leaving Water SensorTE-6300-300
Temperature Resistance (OHMS)
“F “c Nickel
o -18 803
10 -12 830
20 -7 858
1301-11 885 II 4014 I 914 II 50 I 10 I 942 I
I 60 I 16 I 971 I170i 211 1000 I
Accuracy can be determined by measuring sensor resis-tance and making a comparison to the temperature and resis-tance chart. See Table 7. The thin-film nickel sensor has areference resistance of 1000 ohms at 70”F (21 ‘C) and a changein resistance of approximately 3 ohms/F (5 ohms/C). SeeTable 7 for resistance values at selected temperatures.
Temperature Resistance (OHMS)
“F I “c Nickel
90 32 1060
100 38 1090
110 I 43 I 1121
120 49 1152
Honeywell Leaving Water Sensor
The C71 73A and C71 70A are sensors for use in applicationsrequiring a broad temperature sensing range. Unlike ther-mistors, the C71 73A and C71 70A have a positive temperaturecoefficient (PTC); resistance increases as the temperatureincreases. As shown in Table 8, the resistance curve increasesby 4.8 ohms per degree F temperature rise [8.6 ohms/C].
Resistance in the sensor wiring positively offsets the tem-perature sensed by 1 degree F every 4.8 ohms [8.6 ohms/C] of
resistance. Use short wire lengths or larger gauge wire whenlonger lengths are necessary.
With an accurate thermometer (+/-1 “F [,5”C]), measure thefluid temperature at the sensor location, allowing time for thethermometer to stabilize before reading. Use an ohmmeter tomeasure the resistance across the sensor wires. Then verifysensor accuracy with the temperature/resistance values inTable 8.
Table 8: Honeywell Temperature/Resistance Table for C71 73A, Leaving Water Sensor
T~:P or.r~s y OHMS T~~p OHMS y’ OHMS T~:P OHMS y OHMS T~~P oHMs T!:p OHMS
23 3224.8 32 3268.0 41 3311.2 50 3354.4 59 3397,6 66 3440.8 77 3464.0 86 3527,2
24 3229,6 33 3272.8 42 3316.0 51 3359.2 60 3402.4 69 3445.6 78 3488.8 87 3532.0
25 3234.4 34 3277.6 43 3320.8 52 3364.0 61 3407.2 70 3450.4 9 3493.6 88 3536.8
26 3239.2 35 3262,4 44 3325.6 53 3366,8 62 3412.0 71 3455.2 80 3498.4 89 3541.6
27 3244.0 36 3287.2 45 3330.4 54 3373.6 63 3416.8 72 3460,0 81 3503.2 90 3546,4
28 3248.8 37 3292.0 46 3335.2 55 3378.4 64 3421.6 73 3464.8 82 3508.0 91 3551.2
29 3253.6 38 3296,6 47 3340.0 56 3383,2 65 3426.4 74 3469.3 63 3512.8 92 3556.0
30 3258.4 39 3301.6 48 3344.8 57 3388.0 66 3431.2 75 3474.4 84 3517.6 93 3560.8
31 3263.2 40 3306.4 49 3349.6 58 3392.6 67 3436.0 76 3479.2 65 3522.4 94 3565,6
Page 8 I IM 552
Additional Features
The following features are also included with the controlleralgorithm operation, Where there is a point number specifiedafter the feature name (e.g., A13), a sensor or contact closureinput is required.
Leaving Water Low LimitIf the leaving water sensor reads a reliable value below anadjustable Leaving Water Low Limit (LWLL) for more than 3seconds, the compressor command will be forced to 0%immediately. Once the Leaving Water Temperature risesabove the LWLL by a LWLL Differential (LWLLD), a normalcontrol sequence will be initiated. Default values are 15°F forthe LWLL and 5eF for the LWLLD. Leaving Water Low Limit willeffect compressor commands only. The default value for theLeaving Low Limit and Differential is adjustable through theZone Terminal, HVAC PRO Software, or Johnson ControlsFacility Management System.
Demand Limit Input - Analog Input (All)Demand Limit Input will effect the control strategy as follows.This Al will inversely limit the compressor command for externaldemand limiting control strategies. As the input goes from 0-10 VDC, the compressor command will be proportionallylimited from 100% to O%. For example, if the Demand LimitInput is 5 VDC, the compressor command cannot exceed 50%,if 8 VDC is present, the maximum compressor commands willbe 20% and so on. The Demand Limiting function can operatewhen the control is in the Occupied mode only. Demand limitingwill not occur while in the Ice Mode.CAUTION: For the demand limit Input feature, use only 0-10VDC input.
Cooling DiagnosticsThe leaving water temperature sensor will be used to determinea drop in leaving water temperature overtime whenever a stageis energized. When a stage is energized, if the Leaving WaterTemperature does not drop by 1“F in five minutes, this isconsidered a Cooling “Stage Failure.” This failure point can bemonitored with the use of a Zone Terminal or Johnson ControlsFacility Management System. Once a Failure has occurred fora particular stage, the alarm can only be cleared by producingthe change in temperature over time or by cycling power.
Shutdown Mode (B1-1)When shutdown mode is enabled, all stages will be de-ener-gized.
Compressor Lead/Lag Control (B12)If Lead/Lag Control is desired, a BI (Binary Input) point can beconfigured to initiate the mode of operation. When B12is open,circuit 1 is the lead, When B12is closed, circuit 2 is the lead. Thelead circuit will not change unless all stages are off.
Flow Interlock Input (B14)After a transition from Shutdown Mode or Restart Delay thecontroller will wait 10 seconds for a verification of Pump Status.If Pump Status is verified during this time, normal control willoccur. If Pump Status is not verified, a “Pump Failure” point willbe initiated. If Pump Status had previously been verified, andthen is lost for a period of three seconds, the compressor commands will be forced to zero. If Pump Status is lost for aperiod of 10 seconds (Pump Status Delay Timer), the PumpFailure Alarm will be initiated. Once Pump Status is againverified, normal control will occur and the Alarm will be cleared.
IM 552 I Page 9
Setting and Adjustments
Setpoint KnobHVAC Applications—Typical setpoints for HVAC applications or rapid cycling occurs, widen the control band setpoint.range from 42°F to 50”F [5°C to 10“C]. These setpoints may SnyderGeneral recommends the following formulator calculat-change due to many factors, including desired space temperi- ing the minimum Control Band Setpoint:ture, required/desired humidity conditions, etc. Temperature drop across vessel (AT) at full load/number of
Control Band Knobstages + .5”F.
Set for the desired control band in accordance with the followingExample:
formula. Increasing the control band slows down the response10°F AT/4 stages of cooling +.5°F = 3°F control band.
of the AS-UNT33n-l. and increases the temperature deviation. Reset Knob
System Checkout and TroubleshootingEquipment needed:1.Digital Voltmeter2.Resistor Harness (AS-KITI 00-0)
Table 9: Troubleshooting
Step Action Verification
1 Disconnect power to AS-UNT33n-l.
2 Disconnect compressor and unloader line voltage power. Check for OVAC at compressor and unloader contactor:
or relays.
3 Remove Fast-On for Control Band input from A16 and
connect resistors as shown.
E
Al CM A16
Y+
&+ 15VDC
4 Set Setpoint knob on AS-UNT33n-l to 10OF (-12“C).
5 Turn 24 VAC power onto the AS-UNT33n-l. Check for 24 VAC power at AS-UNT33n-l
6 After approximately 70 seconds, all stages will be All LED’s should be ON, The number of stage LED’s
energized quickly in an ascending order. illuminated should correspond to the control model num
ber. If there is a discrepancy, the stage selection DIP
switch (A12)should be checked for proper settings. Refer
to page 2, Figure 1, Table 5.
7 Move Setpoint to60”F(16“C).
8 All stages should now be turned off quickly in a All LED’s should be OFF.
descending order.
9 Remove power from AS-UNT33n-l terminals. Check for OVAC at compressor and unloader contactors
or relays.
10 Reconnect all wiring as originally installed.
11 Reconnect AS-UNT33n-l power supply, close System is now operational.
Compressor disconnects and place setpoints as desired
Lowering the control band speeds up the response of the AS- This adjustment adds to the Leaving Water Setpoint, when theUNT33n-1, while decreasing the temperature deviation fromSetpoint.
control is factory downloaded to incorporate an Outdoor Air,Zone Temperature, or Return Water Reset function. The
The control band setpoint should be as narrow as possible standard application does not include reset; therefore, thiswithout causing hunting or rapid cycling. If instability, hunting setpoint is disregarded in the algorithm.
Page 10/ IM 552
FeaturesRequiringFactoryConfigurationand/orFieldAdjustmentReset Options
One of the following three reset options can be selected:Outdoor Air Reset, Zone Temperature Reset, and ReturnWater Reset. The reset options described below operate onidentical strategies. The main differences are Setpoints andsensor locations.
Leaving Water Setpoint and Leaving Water Reset Band areadjustable using the Setpoint adjustment knobs on the front ofthe AS-UNT33n-l.
Outdoor Air, Zone Temperature, and Return Water HighLimits and their respective Reset Bands are values that can beadjusted by use of a Zone Terminal, HVAC PRO Software, orJohnson Controls Facility Management System.
Ramping StrategyThis ramping strategy applies to all three reset options. Whena reset function is used, a Ramping of the Compressor Com-mand is also used. Two adjustable variables setup the ramp asneeded. These are Ramp Output and Ramp Time. TheRamp is used to meter the Proportional Command into theSequencer when conditions don’t require a quick startup of allstages. For example, if the Outdoor Air Temperature (OAT) isat Outdoor Air Low Limit (OALL), with OALL being equal toOutdoor Air High Limit minus Outdoor Air Reset Band (OAHL- OARB), the stages do not need to be energized as quickly asthey do if the OAT is at the Outdoor Air High Limit (OAHL).When the OAT is at OAHL, the Proportional Command is fedto the Sequencer at the same rate as it is calculated. But if theOAT drops below the OAHL, the Proportional Command isramped to the Sequencer. This allows for a slower startup ofstages.
Outdoor Air ResetWhen this option is chosen, an Outdoor Air Temperature (OAT)sensor (All )is required.
Four variables are used to setup the reset ramp that calculatesthe Actual Leaving Water Setpoint. These are: Leaving WaterSetpoint (A14), Leaving Reset Band (A15), Outdoor Air HighLimit (OAHL); and Outdoor Air Reset Band (OARB).
Figure 7: Sensor Wiring for Reset Options:
1 c Al-1
Al-1 COM
Figure 8: Outdoor Air Reset
I I I
OALL~oAHOALL=OAHL - OARB) OARB
As the OAT increases above the Outdoor Air Low Limit (OALL),the Actual Leaving Water Setpoint is decreased from its Leav-ing High Limit (Leaving Water Setpoint plus Leaving ResetBand) to the Leaving Water Setpoint. When OAT reaches theOAHL, the Actual Leaving Water Setpoint equals the LeavingWater Setpoint (A14). If the OAT sensor is missing or unreliable,no reset occurs and the Actual Leaving Water Setpoint equalsthe Leaving Water Setpoint. If the Leaving Water Sensor (A13)becomes unreliable, the compressor command is forced to 0’%..
Outdoor Temperature Lockout: Ifan Outdoor Air Tempera-ture sensor is installed and reliable, the shutdown mode isinitiated whenever it senses, for more than five minutes, aninput below the adjustable Outdoor Temperature Lockout (OTL)Setpoint (45”F).
The default value for this Setpoint is adjustable through theZone Terminal, HVAC PRO Software, or Johnson ControlsFacility Management System.
Zone Temperature Lockout: When this option is chosen, aZone Temperature must be made available to the controller,There are two ways to do this. The first is through an adjustableAnalog Data Float (ADF) point. With the use of a JohnsonControls Facility Management System, a Zone Temperature oraverage of multiple Zone Temperatures can be shared with thecontroller through the ADF point. The second is through a ZoneTemperature Sensor connected directly to the controller. Re-gardless of which method is used, the control strategy is thesame.
IM 552 I Page 11
Figure 9: Averaging Zone Temperature Using MultipleJohnson Controls TE-641OS-2OO-O (METASTAT) Sensors
sensor sensor sensor
Four variables are used to setup the reset ramp that calculatesthe Actual Leaving Water Setpoint. These are: Leaving WaterSetpoint (A14), Leaving Reset Band (A15), Zone TemperatureHigh Limit (ZTHL), and Zone Temperature Reset Band (ZTRB).
Figure 10: Zone Temperature Reset
LWRB
r \LWSP
ZTU=ZTHL - ZTRB)
As the Zone Temperature increases above the Zone Tempera-ture Low Limit (ZTLL), the controller decreases the ActualLeaving Water Setpoint from its Leaving High Limit (LeavingWater Setpoint plus Leaving Reset Band) to the Leaving WaterSetpoint. When the Zone Temperature reaches the ZTHL, theActual Leaving Water Setpoint equals the Leaving WaterSetpoint (.14). If the Zone Temperature sensor is missing orunreliable, or if there is an unreliable Zone Temperature valueat the Analog Data Float (ADF) point, no reset occurs and theActual Leaving Water Setpoint equals the Leaving WaterSetpoint. If the Leaving Water Sensor (A13) becomes unreli-able, the compressor command is forced to 0%..
Return Water ResetWhen this option is chosen, a Return Water Temperature(RWT) sensor (All) is required. Four variables are used tosetup the reset ramp that calculates the Actual Leaving WaterSetpoint. These are: Leaving Water Setpoint (Ai4), LeavingReset Band (.15), Return Water High Limit (RWHL), and I
Return Water Reset Band (RWRB).
Figure 11: Return Water Reset
LWRB
r ~ \LWSP
RWLL=RWHL- RWRB) tiRB
As the RWT increases above the Return Water Low Limit(RWLL), the controller decreases the Actual Leaving WaterSetpoint from its Leaving High Limit (Leaving Water Setpointplus Leaving Reset Band) to the Leaving Water Setpoint. WhenRWT reaches the RWHL, the Actual Leaving Water Setpointequals the Leaving Water Setpoint (.14). If the RWT sensor ismissing or unreliable, no reset occurs and the Actual LeavingWater Setpoint equals the Leaving Water Setpoint. If theLeaving Water Sensor (.13) becomes unreliable, the compres-sor command is forced to O%.
When Return Water Reset is chosen, a Fail Smart Logicoption is also available. This option works as follows. If theLeaving Water Sensor (A13) becomes unreliable, the controllerswitches from Leaving Water control to Return Water control.Actual Return Water Setpoint equals Leaving Water Setpoint(A14) plus an adjustable Leaving Water Setpoint Offset. Thisvalue takes into account the temperature differential betweenLeaving and Return water temperatures, which is typicallyabout 10“F. If both the Leaving and Return water sensors areunreliable, the compressor is forced to 07..
Page 12/ IM 552
Zone Terminal User’s GuideIntroduction
This user’s guide contains step-by-step instructions for usingthe Zone Terminal (AS-ZTU330-1 ) on a McQuay ReciprocatingChiller (AS-U NT33n-l ). This guide assumes you are familiarwith the McQuay Reciprocating Chiller.
This guide contains examples of the Zone Terminal (ZT)screen that is standard with the ZT accessory to the McQuayReciprocating Chiller.
User’s Guide OrganizationThree major sections describe how to use the Zone Terminal.
Introduction and OverviewExplains in general terms the features and operating modes ofthe Zone Terminal.
Getting StartedIncludes an explanation of the keys, displays, and symbols onthe Zone Terminal. Also includes an explanation of the ZoneTerminal labels and how to install them. In addition, this sectioninstructs the user about handling Alarm Status and connectingthe Zone Terminal.
Making ZT AdjustmentsIncludes specific instructions for making set point adjustmentswith the Zone Terminal.
Overview of the zone TerminalThe Zone Terminal (ZT) is a hand-held or wall-mounted devicethat monitors and adjusts your McQuay Reciprocating Chillerinformation.
A standard telephone-style jack connects the ZT to theMcQuay Reciprocating Chiller controller directly or through theTE-6410S-200-0 Zone Temperature Sensor.
FeaturesThe ZT provides:
. Portability
. Simultaneous monitoring of three different setting:or values
● Easy operation with only seven buttons
. Flashing numbers to show which items are ZT adjustable
● Flashing symbols to notify you of alarm conditions
CapabilitiesWith the ZT, you can:
. Quickly identify a chiller alarm and its location
. Monitor and adjust up to 18 different settings
To familiarize yourself with the ZT, refer to Figure 12.
Fiaure 12: Zone Terminal Template (See Glossary for definition of template terms)
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IM 552 I Page 13
Operating ModesTwo operating modes are included: Monitor and Adjust.
Monitor ModeAssoon as the ZT is connected, it completes a self-check, andstarts up in the Monitor Mode. Monitor Mode lets you view upto three of chiller settings/sensed values at a time.
To allow you to monitor your system, a clear plastic Insert(factory made and installed) relates the ZT’s output to yourMcQuay Reciprocating Chiller system.
You can simultaneously monitor the chiller in three ways:
. Monitor up to three settings/sensed values, A maximumof six items are accessible in each of the three displays.
. Read the symbols to the right of the display numbers tolearn the on/off status of various inputs, outputs, or modes(1= On status; O = Off status). This provides continuous
monitoring of 18 different statuses (on/off).. Monitor alarm status-a flashing red alarm light and any
flashing symbol (1, O, A) visually notifies you when yourchiller has an alarm condition.
Adjust ModeIn Adjust Mode, the ZT displays information in each of the threenumerical displays. Typically, the displays are set up so that therelationship between the values can be viewed simultaneously.For example:
Display 1 = Lvg Water TempDisplay 2 = Lvg SetpointDisplay 3. Comp Command
This operating mode allows you to adjust any flashing setpoints.Setpoints adjusted by the ZT remain in effect until you changethem.
Getting StartedDisplays, Symbols, Keys and ButtonsThe Zone Terminal simultaneously displays three set points orsensed values. In addition, flashing symbols indicate whenitems are in a state of alarm. The keys, buttons, displays, andsymbols are explained below
Table 10: Displays, Symbols, Keys, Buttons
Displays,Symbols, Keys,Buttons Description
Display Button Select the value you want to
1,2,3 monitor or adjust.
Enter Key Use to commit your changes.
Adjustments are not processsd
unless you press Enter.
Flashing Numbers Appear in Display 1, 2, or 3 to
indicate numbers you can adjust.
Numbers that do not flash are
monitor only numbers.
Flashing Shows an item is in alarm
A, O,(l) IMode Selector Button Press this button to select Operating
I I Modes: Monitor, Adjust, Password,
Time Scheduling. A green Mode
I I Indicator light moves through the
modes.
I 1
On/Off Status Observe On/Off conditions of a point
Symbols( I ) for On/a
circle (0) for Off
in the HVAC controller with these
symbols. A bart(l ) for On, a circle
(0) for Off. These are always
I I monitor only items. If the symbol
Red Alarm Light
Up (f)or Down (/)
Arrow Keys
●
flashes, item is in alarm.
Flashes anytime a problem exists
regardless of which Operating Mode
vou have enterad.
Use these keys to adjust a
flashino number.
Appears in the displays, and
corresponds to the item you are
Installing the Plastic LabelsNote: The insert is normally factory-installed. These steps are
required only if the insert is not already installed.
To use the Zi_, you’ll need the plastic label which is included withyour ZT.
InsertThe clear plastic Insert is a custom-made label unique to yourchiller. Use this Insert when monitoring or adjusting specificitems of your system:
1. With the ZT on a flat surface, press the white tab with yourindex finger (Figure 13).
2. Pull the front cover of the ZT away from the back and slidethe Insert into position.
3. Press the ZT together, With the Insert in place and the ZTconnected, the ● in the top position of each displav lines,.up with the first word.
Figure 13: Installing the Insert
I I monitoring or adjusting.
Page 14 I IM 552
Connecting The Zone TerminalYou can wall-mount the ZT, or use it as a portable tool forconvenient access to any chiller information.
McQuay Reciprocating Controller ConnectionA standard telephone-style jack connects the ZT to a McQuayChiller Controller directly or through aTE-6410S-200-0 sensor.
Figure 14: Connecting ZT to a Reciprocating ChillerController Using 6 to 8 Pin Cable - -
6 PinConnection
Figure 15: Connecting ZT to aTE-6410S-200-0 (METASTAT)Sensor Using Coiled 6 to 6 Pin Cable
Open cover.
Alarm StatusThe ZT indicates an alarm as follows (see Figure 12):
. The warning signal (s) flashes to the right of the DisplayIndicator dot ( I ) if the system operating values are inalarm.
. The On/Off Status bar(I) or circle (m) flashes when an On/Off status is in alarm.
. The red alarm light to the right of the Mode Selector Panelflashes when any of the above items are in alarm.
Alarms cannot be cleared with the ZT. The problem must becorrected by maintenance or repair of the affected item.
Making Zone Terminal Adjustments
Adjusting Control SettingsYou can adjust only a flashing number with the ZT. If thenumber does not flash, that item is a monitor only item. AdjustControl Settings in Display 1,2, or 3 as follows:1. Press the Mode Selector Button until the green Mode
Indicator Light moves next to the word Adjust.2. Press either Display Button 1, 2, or 3 to locate adjustable
items, which are indicated by flashing numbers. If youcontinue pressing the display buttons, the dot ( I ) in eachdisplay changes positions and the corresponding numberappears.
3, Press the Up (!) or Down(J) Arrow key until you reach thenumber you want to enter. If you hold down the Up (~) orDown (J) Arrow keys, you can speed through the numbersmore quickly. Press Enter. After you press Enter, thenumbers stop flashing for a few seconds. This pause tellsyou the ZT has processed your adjustment.
4. Press any of the Display Buttons to make other adjust-ments, and repeat Steps 2 and 3.
Note: Some adjustable set points have high and low limitsbeyond which you cannot adjust them.
Adjustable PointsThe following McQuay Reciprocating Chiller points are adjust-able by the Zone Terminal.
Table 11: Adjustable Points
Full Point Name Template name
Leaving Low Limit Lvg Low Limit
Low Limit Differential Low Limit Diff
Ice Mode Setpoint Ice mode Setpt
Failsoft Setpoint Failsoft Setpt
Cool Diagnostic Time Cool Diag Time
Cool diagnostic Temperature Cool Diag Temp
Refer to the Glossary (next section) for definitions of tem-
plate terms.
IM 552/Page 15
Zone Terminal Glossary
Chiller OffA “1” indicates the chiller is in Shutdown Mode.
Ckt 2 LeadA “1” indicates circuit 2 is lead circuit.
Comp CommandThe Compressor Command is the percent of Chiller capacitythat is required.
Cool Diag Time/TempWhen a compressor stage is started, the controller must sensethe Leaving Water Temperature change (Cool Diag Temp)within a time span (Cool Diag Time) or a Full Stage Alarm willoccur,
Demand LimitThe percentage by which the maximum Compressor Com-mand of 100% is reduced.
Failsoft SetptIf the adjustable Leaving Water Setpoint setting ion the face ofthe controller fails, the failsoft setpoint is the value the LeavingWater Setpoint defaults to.
Fail Stage nA “1” indicates a possible fault condition exists.
Low Limit DiffThe amount the Leaving Water Temperature has to increaseabove the Leaving Water Low Limit to allow compressors torestart.
Lvg Cntrl BandThe Leaving Water Control Band is centered around theLeaving Water Setpoint. When the Leaving Water Tempera-ture is within the Leaving Water Control Band, stages will not beenergized or de-energized.
Lvg Dead BandThe Leaving Water Dead Band is one half of the Leaving WaterControl Band.
Lvg Low LimitWhen Leaving Water reaches the Leaving Water Low Limit, theCompressor Command will be forced to 0%.
Lvg Prop BandThe Leaving Water Proportional Band is the Leaving WaterDead Band multiplied by the number of stages,
Lvg Reset BandWhen reset functions are used, the Leaving Water Reset Bandis the amount the Leaving Water Setpoint is automaticallyincreased. The Leaving Water Reset Band adjustment can befound on the face of the controller.
Lvg SetpointThe Leaving Water Temperature setting by which the controllerwill control to. The Leaving Water Setpoint adjustment can befound on the face of the controller.
Lvg Water TempThe temperature of the leaving water from a McQuay Recipro-cating Chiller.
Ramp Output/TimeRamp Output and Time are used to determine softstart. Theydefine the percentage rate of increase for the CompressorCommand.
Stage nA “1” indicates stage is energized.
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