Page 1
Installation and
MeQuw@
Microprocessor-Based
Leaving Water Control
Model AS-UNT33n-l
This controller is offered as an option on ALR “C vintage and
WHR “D” vintage packaged chillers where control of Leaving
Water Temperature is desired. On these units with the controlIer factory installed, the control is preset and calibrated and
should not need any adjustment other than the control setpoint.
For further information on the AS-UNT33n-l microproces-
Maintenance Data
Bulletin No. IM 552
December, 1993
Form No. 573899Y
sor-based Leaving Water Controller and accessories contact
SnyderGeneral Corporation for specification sheets for each
individual control,
The controller and sensor covered in this installation and
maintenance data bulletin are available as substitute replacements 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
01993 SnyderGeneral Corporation
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
Page 2
Introduction
General Description
The AS-UNT33n-l microprocessor-based leaving water control is designed to control multiple capacity steps of coolin9from
a single sensor.
The AS-UNT33n-l operation is based on an adjustable
setpoint and control band as shown in the “operation” section
of this document. If the Leaving Chilled Water Temperature
begins to rise to the desired setpoint plus control band/2 (upper
limit), Cooling Stage 1 brings on the first stage of cooling.
Additional stages of cooling will follow as long as the Leaving
Water Temperature remains above the upper limit of the control
band. As the leaving water temperature begins to drop to
setpoint minus control band/2 (lower limit), cooling stages will
Standard Control Characteristics
Table 1: Standard Control Characteristics
DESCRIPTION
I
Setpoint Range
Control Band Range
Interstate On Delay Between
Stages
Minimum Off Time (each stage)
Minimum On Time (each stage)
Soft Start During Start-up
AS-UNT33n-l
10”F to 60”F (-12-C to +15-C)
Adjustable
I
O-F to 10“F (O-Cto 60”)
Adjustable
60 seconds
5 Minutes
60 Seconds
50% command over 5 minutes
SETTING
begin to de-energize.
There will be no energizing orde-energizing of cooling stages
as long as the leaving water temperature is between the upper
and lower limits of the control band.
As a rule, anytime the leaving water temperature is above the
upper limit of the control band, stages will be energized, and
anytime the leaving water temperature falls below the lower
limit of the control band, stages will be de-energized.
At the initial start of the unit a time delay will occur. There is a
60-second Interstate On Delay between stages. Each stage
incorporates minimum on and off timers with a maximum cycle
rate of six cycles per hour.
Table 2: Controller Specific Characteristics
CONTROLLER
DESCRIPTION
AS-UNT330-I
AS-UNT332-I
AS-UNT334-1
AS-UNT336-1
NUMBER OF
STAGES
4or6
8
4or6
8
LEAVING WATER
SENSOR
Honeywell
Honeywell
Johnson Controls
Johnson Controls
Caution: Offering this control device is not intended to imply
that rapid cycling of compressors iscondoned by SnyderGeneral.
If an application produces rapid cycling, the control and/or the
application must be reviewed and altered to prevent compressor failure.
AS-UNT33n-l
Electrical Ratings”:
Input voltage and frequency (terminals
24 VAC-COMMON) 20 to 30 VAC at 50/60 Hz
(50 Hz requires download.)
Power Consumption:
25 VA at 24 VAC and 50/60 Hz
Input Signal:
Honeywell sensor—positive temperature coefficient of 4.8
ohms/Degree F; resistance of 3484 ohms at 77”F. Johnson
Controls 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.
AS-UNT33n-l Accessories
Model No.
Johnson TE-6313P-1
Johnson TE-6300-300 070312401
Sensor Well 047441506
Johnson TE-6410S-200-0 070312801
Johnson AS-ZW330-1
Honeywell C7173AI 017
Honeywell C7170AI 010
Honeywell 121 371A 046442403
Honeywell 121371E
Johnson AS-KITIOO-O
Page 2 I IM 552
McQuay Pert No. Quantity Description
070312301
070312701 1 Zone Terminal
048442405
046442402
048442404 1
1 Outdoor Air Sensor
1
1 Immersion Well
depends on Zone Temperature Sensor
#of zones
1 Immersion Sensor (30 ft. cord)
1 Immersion Sensor (10 ft. cord)
1 Copper Immersion Well
1 Resetor Test Kit
Specifications
Humidity Rating:
5 to 90% RH noncondensing.
Leaving Water Sensor:
The Honeywell C7173AIOI 7, Honeywell C7170AI 010, or
Johnson Controls TE-6300-300 senses Leaving Water Temperature on control terminals A13 and A13 COM.
Table 3: Contact Rating
CONTACT
N.O.
NC, 24
NO. 120/240
NC, 120/240
Immersion Sensor (30 ft. cord) Senses Leaving or Return Water Temperature
Stainless Steel Immersion Well Used with C7173AI017 or C7I7OA1OIO
VOLTAGE (V)
24
Application
Used for reset of Leaving Water Setpoint.
Used with TE-6300-300
Used for zone temperature reset
Used for monitoring and local control of
designated points
Sensing of Leaving Water Temperature
Sensing of Leaving Water Temperature
Used with C7173AIO17 or C7170AIOI0
Used for field diagnostics.
INRUSH (VA)
240
75
750
240
RUNNING (VA)
60
30
75
40
Page 3
Installation
Standards Compliance
The UNT Controller complies with the following standards:
1
● CSA C22.2 No. 205
● IEEE 446
● IEEE 518 ● FCC Part 15, Subpart A, Class J
● UL916
● VDE 0871 Class B “ IEEE 587 Category A
● IEEE 472
● NEMA ICS 2, Part 2-230
All wiring must comply with local codes and ordinances:
Disconnect power supply before making connections to
1.
avoid electrical shock and/or equipment damage.
Check ratings given inthe specification and on the product
2.
to make sure the controller fits the application.
Choose a location for the AS-UNT33n-l controller that is
3.
Do not run low-voltage wiring in the same conduit as linevoltage wiring (30 VAC or above) or wiring that switches
power to highly inductive loads (such as contractors,
coils, motors, or generators).
not 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 the
4.
mounting holes in the base. (See Figure 2,)
Install immersion well and sensor bulb in the Leaving
5.
Chilled Water piping as instructed bythe installation manual
for the unit being controlled.
Connect 24 VAC to terminals marked 24 VAC and COM.
6.
CAUTION: Never spark the 24 V power leads to check
for power.
7. Wire the compressor and capacity controls steps to the
individual controller relay terminals as shown in the unit
wiring diagram.
8. Adjust SW1 and SW2 on A12 for the appropriate
number of cooling stages. The AS-UNT330-l/ASUNT334-1 is factory set for 6 stages by Johnson
Controls. The AS-UNT332-l/AS-UNT336-l is factory
set for 8 stages. Refer. o Table 5 and Figure 1.
L
Table 5: Dipswitch Settings
Oipswitch ettings
AS-UNT 13n-1 Al 1 A12
AS-UNT330-I
AS-UNT334-1
4 stage selection
(set by others)
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)
10 v ●
SW2
2V
Swl
SW2
T
v ● ●
10 v ●
2V
Swl
T ●
v
10 v ● ●
SW2
2V
Swl
T
v
Factory
Sat
●
,
I I
●
I
I
I
Stage
Select
●
●
●
I
A13
—
—
●
●
—
●
●
—
●
●
—
Factorv Set
A14 A15 A16
● ● ●
● ● ●
● ● ●
● ● ●
● ● ●
● ● ●
Figure 1: Analog Input Switches
I
w
Ardog Inputswitches
IM 552 I Page 3
Page 4
Dimensional Data
—
—
Figure 2: Dimensional Data
+mrL3L-
,Iuiuullin’u”i: II~lll_l I
II I&p--’
,0
5.80
r 1-
-
@
‘1
1
L
1.24
1
eF
.
.
—
m
Ly
0)
—
I
1-
~ = mounting holes
A 7il
*I
o“ I
-1
Page4/ IM 552
Page 5
DEMAND LIMIT*
(1)
0-10 VDC
LEAVING
SHUTDOWN*
COMP LEADILAG*
Wiring
Figure 3: Wiring Diagram
25
(+)
—
(-)
Al CM
A=
00
Al CM
~~ p
+15VDC +15VDC G
—— I
24VAC BI
A12
T ,
A16
1
B14 ~
h
(2)
FLOW INTERLOCK
* Indicates
optional
feature.
(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
24VAC
18
28
n
512/518
519 +
I
Note:
g;— g;. ;
z
❑
~
)
#
Refer to Unit Wiring
Diagram for Stage
Wiring.
:
I
IM 552/ Page 5
Page 6
Table 6: Wiring Location Cross Reference
Lead #
512
518
519
522
524
525
526
527
528
529
400 OHM
Resister
600 OHM
Resister
600 OHM
Resister
523
535
536
537
538
H~Y#
TB3-18 to TB3-29
Tb3-29 to “TR”
“TR”
Ground
“7”
TB3-23 to TB3-24
“6”
“P” to “Pi”
“1-”
“Tl”
“7” to “6”
“7” to “e”
“7” to “e”
Ground
. .
1
“2”
“.
3
“.
4
Stages
(4,6,8, Stages)
“
“
“
“
“
“
“
“
“
4 Stages
6 Stages
8 Stages
8 Stages
,,
,,
,,
“
Johnson Controls (JCI)
AS-UNT33n-l
Not Needed (See Note 0 and@)
TB3-18 to 24 VAC
Common
Not Needed
Not Needad (See Note@)
Not Needed
Not Needed (see Note 0)
Not Needed or Zone Terminal
Adjust
AI-3 (JCI or HN Leaving Water
Sensor. See appropriate
sensor section)
AI-CM (JCI or HANLeaving Water
Sensor. See appropriate
sensor section)
See Table 5
Not Needed
Not Needed
Not Needed
Not Needed
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
Page 7
Operation
Chiller System
Chiller systems are used to provide cold water for comfort
cooling or process applications. Control of the compressor
operation to supply that cold water maybe initiated by sensing
Return Water Temperature or Leaving Water Temperature. If
precise control of Leaving Water Temperature is desired a ASUNT33n-1 controller is recommended.
Leaving Water Temperature Control Operation
Leaving Water Temperature will be controlled to the Actual
Leaving Water Setpoint. The Actual Leaving Water Setpoint will
be a function of what mode of operation the controller is in and
if a reset option is used. The Control Band potentiometer located
on the front of the controller is used to determine the Actual
Leaving 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 F
Number of Stages = 6
Dead Band. 4/2 = 2 Deg F
Prop Band= 2*6=12 Deg F
As the Leaving Water Temperature rises above the Actual
Leaving Water Setpoint, but within the Leaving Dead Band,
there will be no increase in the Compressor Command. As the
Leaving Water Temperature continues to rise above the Dead
Band and into the Prop Band, the Compressor Command will be
increased. When Leaving Integration Gain is used, a Proportional Plus Integral command will be calculated. As the Compressor Command increases, stages of cooling capacity will be
energized. Minimum on, off, interstage times, and cycles per
hour attributes will control the stages.
As the Leaving Water Temperature decreases towards the
Actual Leaving Water Setpoint, the Compressor Command will
be decreased. Upon reentering the Dead Band, the current
Compressor Command will be maintained. Ifthe Leaving Water
Temperature falls below the Actual Leaving Water Setpoint
(using the same Dead Band), the Compressor Command will
again start to decrease.
The “Control Band” is the non-staging area of the control.
Anytime the Leaving Water Temperature isoutside of the control
Figure5: Chiller System
CONTROL
I
J
I
LEAVING
WATER
SENSOR
I
Figure 6: AS-UNT33n-l Leaving Water Control Algorithm Operation
w=ENsOR ‘UMP
COOLING LOAD
RESET
(optional)
l\
J
band limits, staging will occur. Anytime the Leaving Water
Temperature is within the control band limits, no staging occurs.
As shown in Figure 6, with a 45°F setpoint and a 4°F control band
setting, stages of cooling energize when the Leaving Water is
47°F or higher. Stages de-energize when the Leaving Water is
43°F or lower (4°F difference). All stages will remain in their
current state between 43°F and 47°F.
AS-UNT33n-l LED OPERATION
The AS-U NT33n-l has one LED for each staged output. The
LED on the AS-UNT33n-l will light simultaneously as that
stage relay energizes. If the LED is not lit, the stage is not
energized. When a stage relay energizes, the normally
closed contacts open, and the normally open contacts close,
I
IM 552/ Page 7
Page 8
Johnson Controls Leaving Water Sensor
Note: Johnson Controls or Honeywell Leaving Water
Sensors may be used with the AS-UNT33n-l. Refer to Table
2, page 2. A description of the Honeywell sensor follows the
description of the Johnson Controls sensor.
Table 7: Johnson Controls Leaving Water Sensor
TE-6300-300
Temperature
“F “c
o -18
10 -12
20 -7
1301-11
4014
I
I
50 I 10 I
I 60 I 16 I
170i 211 1000 I
Resistance (OHMS)
Nickel
803
830
858
885
I
914
942
971
I
I
I
I
Honeywell Leaving Water Sensor
Accuracy can be determined by measuring sensor resistance and making a comparison to the temperature and resistance chart. See Table 7. The thin-film nickel sensor has a
reference resistance of 1000 ohms at 70”F (21‘C) and achange
in resistance of approximately 3 ohms/F (5 ohms/C). See
Table 7 for resistance values at selected temperatures.
Temperature
“F
I
90 32
100 38
110
120
43
I
49
“c
Resistance (OHMS)
Nickel
1060
1090
I
1121
1152
The C7173A and C7170A are sensors for use in applications
requiring a broad temperature sensing range. Unlike thermistors, the C7173A and C71 70A have a positive temperature
coefficient (PTC); resistance increases as the temperature
increases. As shown in Table 8, the resistance curve increases
by 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
Table 8: Honeywell Temperature/Resistance Table for C71 73A, Leaving Water Sensor
T~:P
or.r~s
23 3224.8 32
24 3229,6 33 3272.8 42
25 3234.4 34 3277.6 43
26 3239.2 35 3262,4 44
27 3244.0 36 3287.2 45
28 3248.8 37
29 3253.6 38 3296,6 47 3340.0 56
30 3258.4 39
31 3263.2 40 3306.4 49
y OHMS
3268.0 41 3311.2 50
3292.0 46 3335.2 55 3378.4 64
3301.6 48 3344.8 57 3388.0 66
T~~p
OHMS
3316.0 51 3359.2 60
3320.8 52 3364.0 61
3325.6 53 3366,8 62 3412.0 71
3330.4 54 3373.6 63 3416.8 72
3349.6 58 3392.6 67 3436.0 76
y’
OHMS
3354.4 59 3397,6 66 3440.8 77
3383,2 65 3426.4 74
resistance. Use short wire lengths or larger gauge wire when
longer lengths are necessary.
With an accurate thermometer (+/-1“F [,5”C]), measure the
fluid temperature at the sensor location, allowing time for the
thermometer to stabilize before reading. Use an ohmmeter to
measure the resistance across the sensor wires. Then verify
sensor accuracy with the temperature/resistance values in
Table 8.
T~:P
OHMS
3402.4 69 3445.6 78
3407.2 70 3450.4 9
3421.6 73 3464.8 82
3431.2 75
y
3474.4 84 3517.6 93 3560.8
3479.2 65 3522.4 94
OHMS
3455.2 80 3498.4 89
3460,0 81
3469.3 63 3512.8 92
T~~P
oHMs
3464.0 86
3488.8 87 3532.0
3493.6 88 3536.8
3503.2 90 3546,4
3508.0 91
T!:p OHMS
3527,2
3541.6
3551.2
3556.0
3565,6
Page 8 I IM 552
Page 9
Additional Features
The following features are also included with the controller
algorithm operation, Where there is a point number specified
after the feature name (e.g., A13), a sensor or contact closure
input is required.
Leaving Water Low Limit
If the leaving water sensor reads a reliable value below an
adjustable Leaving Water Low Limit (LWLL) for more than 3
seconds, the compressor command will be forced to 0%
immediately. Once the Leaving Water Temperature rises
above the LWLL by a LWLL Differential (LWLLD), a normal
control sequence will be initiated. Default values are 15°F for
the LWLL and 5eF forthe LWLLD. Leaving Water Low Limit will
effect compressor commands only. The default value for the
Leaving Low Limit and Differential is adjustable through the
Zone Terminal, HVAC PRO Software, or Johnson Controls
Facility 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 external
demand limiting control strategies. As the input goes from 010 VDC, the compressor command will be proportionally
limited from 100% to O%. For example, if the Demand Limit
Input is 5 VDC, the compressor command cannot exceed 50%,
if 8 VDC is present, the maximum compressor commands will
be 20% and so on. The Demand Limiting function can operate
when the control is in the Occupied mode only. Demand limiting
will not occur while in the Ice Mode.
CAUTION: For the demand limit Input feature, use only 0-10
VDC input.
Cooling Diagnostics
The leaving water temperature sensor will be used to determine
a drop in leaving water temperature overtime whenever astage
is energized. When a stage is energized, if the Leaving Water
Temperature does not drop by 1“F in five minutes, this is
considered a Cooling “Stage Failure.” This failure point can be
monitored with the use of a Zone Terminal or Johnson Controls
Facility Management System. Once a Failure has occurred for
a particular stage, the alarm can only be cleared by producing
the change in temperature over time or by cycling power.
Shutdown Mode (B1-1)
When shutdown mode is enabled, all stages will be de-energized.
Compressor Lead/Lag Control (B12)
If Lead/Lag Control is desired, a BI (Binary Input) point can be
configured to initiate the mode of operation. When B12is open,
circuit 1 isthe lead, When B12is closed, circuit 2 is the lead. The
lead circuit will not change unless all stages are off.
Flow Interlock Input (B14)
After a transition from Shutdown Mode or Restart Delay the
controller will wait 10 seconds for a verification of Pump Status.
If Pump Status is verified during this time, normal control will
occur. If Pump Status is not verified, a “Pump Failure” point will
be initiated. If Pump Status had previously been verified, and
then is lost for a period of three seconds, the compressor c
ommands will be forced to zero. If Pump Status is lost for a
period of 10 seconds (Pump Status Delay Timer), the Pump
Failure Alarm will be initiated. Once Pump Status is again
verified, normal control will occur and the Alarm will be cleared.
IM 552 I Page 9
Page 10
Setting and Adjustments
Setpoint Knob
HVAC Applications—Typical setpoints for HVAC applications
range from 42°F to 50”F [5°C to 10“C]. These setpoints may
change due to many factors, including desired space temperi-
ture, required/desired humidity conditions, etc.
Control Band Knob
Set for the desired control band in accordance with the following
formula. Increasing the control band slows down the response
of the AS-UNT33n-l. and increases the temperature deviation.
Lowering the control band speeds up the response of the ASUNT33n-1, while decreasing the temperature deviation from
Setpoint.
The control band setpoint should be as narrow as possible
without causing hunting or rapid cycling. If instability, hunting
System Checkout and Troubleshooting
Equipment needed:
1.Digital Voltmeter
2.Resistor Harness (AS-KITI 00-0)
Table 9: Troubleshooting
Step Action
1 Disconnect power to AS-UNT33n-l.
2 Disconnect compressor and unloader line voltage power.
Remove Fast-On for Control Band input from A16 and
3
connect resistors as shown.
or rapid cycling occurs, widen the control band setpoint.
SnyderGeneral recommends the following formulator calculating the minimum Control Band Setpoint:
Temperature drop across vessel (AT) at full load/number of
stages + .5”F.
Example:
10°F AT/4 stages of cooling +.5°F = 3°F control band.
Reset Knob
This adjustment adds to the Leaving Water Setpoint, when the
control is factory downloaded to incorporate an Outdoor Air,
Zone Temperature, or Return Water Reset function. The
standard application does not include reset; therefore, this
setpoint is disregarded in the algorithm.
Verification
Check for OVAC at compressor and unloader contactor:
or relays.
Al CM
Y
+15VDC
E
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
energized quickly in an ascending order.
7 Move Setpoint to60”F(16“C).
8 All stages should now be turned off quickly in a
descending order.
Remove power from AS-UNT33n-l terminals. Check for OVAC at compressor and unloader contactors
9
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
&
A16
+
All LED’s should be ON, The number of stage LED’s
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.
All LED’s should be OFF.
or relays.
Page 10/ IM 552
Page 11
FeaturesRequiringFactoryConfigurationand/orFieldAdjustment
Reset Options
One of the following three reset options can be selected:
Outdoor Air Reset, Zone Temperature Reset, and Return
Water Reset. The reset options described below operate on
identical strategies. The main differences are Setpoints and
sensor locations.
Leaving Water Setpoint and Leaving Water Reset Band are
adjustable using the Setpoint adjustment knobs on the front of
the AS-UNT33n-l.
Outdoor Air, Zone Temperature, and Return Water High
Limits and their respective Reset Bands are values that can be
adjusted by use of a Zone Terminal, HVAC PRO Software, or
Johnson Controls Facility Management System.
Ramping Strategy
This ramping strategy applies to all three reset options. When
a reset function is used, a Ramping of the Compressor Com-
mand is also used. Two adjustable variables setup the ramp as
needed. These are Ramp Output and Ramp Time.
Ramp is used to meter the Proportional Command into the
Sequencer when conditions don’t require a quick startup of all
stages. For example, if the Outdoor Air Temperature (OAT) is
at Outdoor Air Low Limit (OALL), with OALL being equal to
Outdoor Air High Limit minus Outdoor Air Reset Band (OAHL
- OARB), the stages do not need to be energized as quickly as
they do if the OAT is at the Outdoor Air High Limit (OAHL).
When the OAT is at OAHL, the Proportional Command is fed
to the Sequencer at the same rate as it is calculated. But if the
OAT drops below the OAHL, the Proportional Command is
ramped to the Sequencer. This allows for a slower startup of
stages.
The
Outdoor Air Reset
When this option is chosen, an Outdoor AirTemperature (OAT)
sensor (All )is required.
Four variables are used to setup the reset ramp that calculates
the Actual Leaving Water Setpoint. These are: Leaving Water
Setpoint (A14), Leaving Reset Band (A15), Outdoor Air High
Limit (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~oAH
OALL=OAHL - OARB)
As the OAT increases above the Outdoor Air Low Limit (OALL),
the Actual Leaving Water Setpoint is decreased from its Leaving High Limit (Leaving Water Setpoint plus Leaving Reset
Band) to the Leaving Water Setpoint. When OAT reaches the
OAHL, the Actual Leaving Water Setpoint equals the Leaving
Water Setpoint (A14). Ifthe OAT sensor is missing or unreliable,
no reset occurs and the Actual Leaving Water Setpoint equals
the Leaving Water Setpoint. If the Leaving Water Sensor (A13)
becomes unreliable, the compressor command isforced to 0’%..
Outdoor Temperature Lockout: Ifan Outdoor AirTemperature sensor is installed and reliable, the shutdown mode is
initiated whenever it senses, for more than five minutes, an
input below the adjustable Outdoor Temperature Lockout (OTL)
Setpoint (45”F).
The default value for this Setpoint is adjustable through the
Zone Terminal, HVAC PRO Software, or Johnson Controls
Facility Management System.
Zone Temperature Lockout: When this option is chosen, a
Zone Temperature must be made available to the controller,
There are two ways to do this. The first is through an adjustable
Analog Data Float (ADF) point. With the use of a Johnson
Controls Facility Management System, a Zone Temperature or
average of multiple Zone Temperatures can be shared with the
controller through the ADF point. The second isthrough a Zone
Temperature Sensor connected directly to the controller. Re-
gardless of which method is used, the control strategy is the
same.
OARB
IM 552 I Page 11
Page 12
Figure 9: Averaging Zone Temperature Using Multiple
Johnson Controls TE-641OS-2OO-O (METASTAT) Sensors
sensor sensor
sensor
Return Water Reset
When this option is chosen, a Return Water Temperature
(RWT) sensor (All) is required. Four variables are used to
setup the reset ramp that calculates the Actual Leaving Water
Setpoint. These are: Leaving Water Setpoint (Ai4), Leaving
Reset Band (.15), Return Water High Limit (RWHL), and
Return Water Reset Band (RWRB).
Figure 11: Return Water Reset
LWRB
I
Four variables are used to setup the reset ramp that calculates
the Actual Leaving Water Setpoint. These are: Leaving Water
Setpoint (A14), Leaving Reset Band (A15), Zone Temperature
High 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 Temperature Low Limit (ZTLL), the controller decreases the Actual
Leaving Water Setpoint from its Leaving High Limit (Leaving
Water Setpoint plus Leaving Reset Band) to the Leaving Water
Setpoint. When the Zone Temperature reaches the ZTHL, the
Actual Leaving Water Setpoint equals the Leaving Water
Setpoint (.14). If the Zone Temperature sensor is missing or
unreliable, or if there is an unreliable Zone Temperature value
at the Analog Data Float (ADF) point, no reset occurs and the
Actual Leaving Water Setpoint equals the Leaving Water
Setpoint. If the Leaving Water Sensor (A13) becomes unreli-
able, the compressor command is forced to 0%..
\
r ~
LWSP
RWLL=RWHL- RWRB)
As the RWT increases above the Return Water Low Limit
(RWLL), the controller decreases the Actual Leaving Water
Setpoint from its Leaving High Limit (Leaving Water Setpoint
plus Leaving Reset Band) to the Leaving Water Setpoint. When
RWT reaches the RWHL, the Actual Leaving Water Setpoint
equals the Leaving Water Setpoint (.14). If the RWT sensor is
missing or unreliable, no reset occurs and the Actual Leaving
Water Setpoint equals the Leaving Water Setpoint. If the
Leaving Water Sensor (.13) becomes unreliable, the compressor command is forced to O%.
When Return Water Reset is chosen, a Fail Smart Logic
option is also available. This option works as follows. If the
Leaving Water Sensor (A13)becomes unreliable, the controller
switches from Leaving Water control to Return Water control.
Actual Return Water Setpoint equals Leaving Water Setpoint
(A14) plus an adjustable Leaving Water Setpoint Offset. This
value takes into account the temperature differential between
Leaving and Return water temperatures, which is typically
about 10“F. If both the Leaving and Return water sensors are
unreliable, the compressor is forced to 07..
\
tiRB
Page 12/ IM 552
Page 13
Zone Terminal User’s Guide
Introduction
This user’s guide contains step-by-step instructions for using
the Zone Terminal (AS-ZTU330-1 ) on a McQuay Reciprocating
Chiller (AS-U NT33n-l ). This guide assumes you are familiar
with the McQuay Reciprocating Chiller.
This guide contains examples of the Zone Terminal (ZT)
screen that is standard with the ZT accessory to the McQuay
Reciprocating Chiller.
User’s Guide Organization
Three major sections describe how to use the Zone Terminal.
Introduction and Overview
Explains in general terms the features and operating modes of
the Zone Terminal.
Getting Started
Includes an explanation of the keys, displays, and symbols on
the Zone Terminal. Also includes an explanation of the Zone
Terminal labels and how to install them. In addition, this section
instructs the user about handling Alarm Status and connecting
the Zone Terminal.
Making ZT Adjustments
Includes specific instructions for making set point adjustments
with the Zone Terminal.
Fiaure 12: Zone Terminal Template (See Glossary for definition of template terms)
Overview of the zone Terminal
The Zone Terminal (ZT) is a hand-held or wall-mounted device
that monitors and adjusts your McQuay Reciprocating Chiller
information.
A standard telephone-style jack connects the ZT to the
McQuay Reciprocating Chiller controller directly or through the
TE-6410S-200-0 Zone Temperature Sensor.
Features
The 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
Capabilities
With 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.
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IM 552 I Page 13
Page 14
Operating Modes
Two operating modes are included: Monitor and Adjust.
Monitor Mode
As
soon as the ZT is connected, it completes a self-check, and
starts up in the Monitor Mode. Monitor Mode lets you view up
to 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 your
McQuay Reciprocating Chiller system.
You can simultaneously monitor the chiller in three ways:
. Monitor up to three settings/sensed values, A maximum
of six items are accessible in each of the three displays.
. Read the symbols to the right of the display numbers to
learn the on/off status of various inputs, outputs, or modes
(1= On status; O = Off status). This provides continuous
Getting Started
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 your
chiller has an alarm condition.
Adjust Mode
In Adjust Mode, the ZT displays information in each ofthe three
numerical displays. Typically, the displays are set up so that the
relationship between the values can be viewed simultaneously.
For example:
Display 1 = Lvg Water Temp
Display 2 = Lvg Setpoint
Display 3. Comp Command
This operating mode allows you to adjust any flashing setpoints.
Setpoints adjusted by the ZT remain in effect until you change
them.
Displays, Symbols, Keys and Buttons
The Zone Terminal simultaneously displays three set points or
sensed values. In addition, flashing symbols indicate when
items are in a state of alarm. The keys, buttons, displays, and
symbols are explained below
Table 10: Displays, Symbols, Keys, Buttons
Displays,
Symbols, Keys,
Buttons Description
Display Button
1,2,3 monitor or adjust.
Enter Key Use to commit your changes.
Flashing Numbers Appear in Display 1, 2, or 3 to
Flashing Shows an item is in alarm
A, O,(l)
Mode Selector Button
I
I
I
On/Off Status Observe On/Off conditions of a point
Symbols( I ) for On/a
circle (0) for Off
I
Red Alarm Light
Up (f)or Down (/)
Arrow Keys
●
I
Select the value you want to
Adjustments are not processsd
unless you press Enter.
indicate numbers you can adjust.
Numbers that do not flash are
monitor only numbers.
I
Press this button to select Operating
Modes: Monitor, Adjust, Password,
Time Scheduling. A green Mode
I
Indicator light moves through the
modes.
I
1
in the HVAC controller with these
symbols. A bart(l ) for On, a circle
(0) for Off. These are always
I monitor only items. If the symbol
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
monitoring or adjusting.
I
Installing the Plastic Labels
Note: 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 isincluded with
your ZT.
Insert
The clear plastic Insert is a custom-made label unique to your
chiller. Use this Insert when monitoring or adjusting specific
items of your system:
1. With the ZT on a flat surface, press the white tab with your
index finger (Figure 13).
2. Pull the front cover of the ZT away from the back and slide
the Insert into position.
3. Press the ZT together, With the Insert in place and the ZT
connected, the ● in the top position of each displav lines
up with the first word.
Figure 13: Installing the Insert
,.
Page 14 I IM 552
Page 15
Connecting The Zone Terminal
You can wall-mount the ZT, or use it as a portable tool for
convenient access to any chiller information.
McQuay Reciprocating Controller Connection
A standard telephone-style jack connects the ZT to a McQuay
Chiller Controller directly or through aTE-6410S-200-0 sensor.
Figure 14: Connecting ZT to a Reciprocating Chiller
ControllerUsing 6 to 8 Pin Cable - -
6 Pin
Connection
Figure 15: Connecting ZTto aTE-6410S-200-0 (METASTAT)
Sensor Using Coiled 6 to 6 Pin Cable
Open cover.
Alarm Status
The ZT indicates an alarm as follows (see Figure 12):
. The warning signal (s) flashes to the right of the Display
Indicator dot ( I ) if the system operating values are in
alarm.
. 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 Panel
flashes when any of the above items are in alarm.
Alarms cannot be cleared with the ZT. The problem must be
corrected by maintenance or repair of the affected item.
Making Zone Terminal Adjustments
Adjusting Control Settings
You can adjust only a flashing number with the ZT. If the
number does not flash, that item is a monitor only item. Adjust
Control 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 you
continue pressing the display buttons, the dot ( I ) in each
display changes positions and the corresponding number
appears.
3, Press the Up (!) or Down(J) Arrow key until you reach the
number you want to enter. If you hold down the Up (~) or
Down (J) Arrow keys, you can speed through the numbers
more quickly. Press Enter. After you press Enter, the
numbers stop flashing for a few seconds. This pause tells
you the ZT has processed your adjustment.
4. Press any of the Display Buttons to make other adjustments, and repeat Steps 2 and 3.
Note: Some adjustable set points have high and low limits
beyond which you cannot adjust them.
Adjustable Points
The following McQuay Reciprocating Chiller points are adjust-
able by the Zone Terminal.
Table 11: Adjustable Points
Full Point
Leaving Low Limit
Low Limit Differential
Ice Mode Setpoint
Failsoft Setpoint
Cool Diagnostic Time
Cool diagnostic Temperature
Refer to the Glossary (next section) for definitions of template terms.
Name
Template name
Lvg Low Limit
Low Limit Diff
Ice mode Setpt
Failsoft Setpt
Cool Diag Time
Cool Diag Temp
IM 552/Page 15
Page 16
Zone TerminalGlossary
Chiller Off
A “1”indicates the chiller is in Shutdown Mode.
Ckt 2 Lead
A “1”indicates circuit 2 is lead circuit.
Comp Command
The Compressor Command is the percent of Chiller capacity
that is required.
Cool Diag Time/Temp
When a compressor stage is started, the controller must sense
the Leaving Water Temperature change (Cool Diag Temp)
within a time span (Cool Diag Time) or a Full Stage Alarm will
occur,
Demand Limit
The percentage by which the maximum Compressor Com-
mand of 100% is reduced.
Failsoft Setpt
If the adjustable Leaving Water Setpoint setting ion the face of
the controller fails, the failsoft setpoint is the value the Leaving
Water Setpoint defaults to.
Fail Stage n
A “1”indicates a possible fault condition exists.
Low Limit Diff
The amount the Leaving Water Temperature has to increase
above the Leaving Water Low Limit to allow compressors to
restart.
Lvg Cntrl Band
The Leaving Water Control Band is centered around the
Leaving Water Setpoint. When the Leaving Water Tempera-
ture is within the Leaving Water Control Band, stages will not be
energized or de-energized.
Lvg Dead Band
The Leaving Water Dead Band is one half of the Leaving Water
Control Band.
Lvg Low Limit
When Leaving Water reaches the Leaving Water Low Limit, the
Compressor Command will be forced to 0%.
Lvg Prop Band
The Leaving Water Proportional Band is the Leaving Water
Dead Band multiplied by the number of stages,
Lvg Reset Band
When reset functions are used, the Leaving Water Reset Band
is the amount the Leaving Water Setpoint is automatically
increased. The Leaving Water Reset Band adjustment can be
found on the face of the controller.
Lvg Setpoint
The Leaving Water Temperature setting by which the controller
will control to. The Leaving Water Setpoint adjustment can be
found on the face of the controller.
Lvg Water Temp
The temperature of the leaving water from a McQuay Reciprocating Chiller.
Ramp Output/Time
Ramp Output and Time are used to determine softstart. They
define the percentage rate of increase for the Compressor
Command.
Stage n
A “1”indicates stage is energized.
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