Specified Controls SC-Z20 User manual

SC-Z20
Commercial Zone Control System
Modulating or Two-position
Installation Manual

SC-Z20
MODULATING ZONE CONTROL SYSTEM
System Features
• Fully modulating zone dampers and diffusers
• Up to 20 zones
• Auto changeover
• Works with single stage, multi-stage, or heat pump systems
• No programming required
• Auxiliary heat control option for each zone
• Night setback option
• All low voltage wiring
• LEDs indicates status of equipment and zones
• Fused inputs and outputs
System Benefits
• Low Cost
• Simple to wire
• Easy to set up (No Laptop Required)
• Reliable design

SC-Z20
MODULATING ZONE CONTROL SYSTEM
OVERVIEW
The SC-Z20 is a commercial zone control system that allows a single HVAC unit to have up to 20
individual zones. Each zone is controlled by its own space thermostat and a modulating damper.
When a majority of zones are calling for cooling, the system operates in the cooling mode. The SC-
Z20 controls up to two stages of cooling to maintain a cooling discharge air setpoint. If a majority of
zones are calling for heating, the system changes from the cooling mode to the heating mode. The
SC-Z20 then controls up to two stages of heating to maintain a heating discharge air setpoint. When
the number of heating and cooling requests are equal, the system satisfies the cooling request first.
SEQUENCE OF OPERATION
The SC-Z20 controls the system fan, two stages of cooling and two stages of heating. In the
occupied mode, the fan runs continuously. Cooling stages are cycled to maintain a discharge air
temperature of approximately 54° F. Heating stages are cycled to maintain a discharge air
temperature of approximately 140° F. The control panel is equipped with two slide switches
designated “ ” used to increase the number of zones that must be calling before theMinimum Calls
equipment will come on. All stages of heating and cooling have a five minute minimum ON/OFF time.
There is also a ten minute time delay between first and second stage. The system will remain in
whatever mode it is in for a minimum of fifteen minutes. If equal heating and cooling calls take place,
cooling will receive priority. Equipment mode of operation is based on a “Majority Wins” control
algorithm.
UNOCCUPIED MODE
The panel has a set of clock terminals “ ” for occupied and unoccupied scheduling. When the clockT
terminals are open, the system is placed in the unoccupied mode. All stages of heating or cooling are
turned off and the fan shuts off after a five minute delay. See wiring and programming instruction in
this manual for the SC-Z20-NS Night Stat.
WARNING
1. Turn power off to HVAC unit and control panel during installation to prevent serious injury from
electrical shock and/or damage to the system.
2. Use extreme care when making duct openings and handling sheet metal to avoid injury.
3. The SC-Z20 panel and all components must be installed in a conditioned space where the
ambient temperature will not exceed 150° F.
4. Install all components in a manner that provides access for test, check and startup.
CAUTION
1. Installation of this system must be in compliance with all applicable codes.
2. HVAC system must be properly sized and balanced to assure optimum system performance.
3.Abypass damper must be installed to maintain proper system static pressure.
4.All low voltage wire must be 18 gauge.
5.All wiring should be color coded and tagged for proper identification.
6. When landing wires to the control panel, zone thermostats and actuator boards, make sure wires
are snug, but do not over-tighten screw terminals.

SC-Z20
MODULATING ZONE CONTROL SYSTEM
WIRING AND LAYOUT GUIDE
3
SC-Z20-NS
NIGHT STAT
SC-Z20

SC-Z20 PANEL LAYOUT
1
2
3
4
5
6
7
8
9
10
1112
13
14
15
17
18
16
ZONE 13 ZONE 12 ZONE 11 ZONE 10 ZONE 9 ZONE 8 ZONE 7 ZONE 6 ZONE 5 ZONE 4 ZONE 3 ZONE 2 ZONE 1
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
ZONE 20 ZONE 19 ZONE 18 ZONE 17 ZONE 16 ZONE 15 ZONE 14 24VAC
R
C
NOT USED
R
C
T
T
NS
NS
E
E
DAS
DAS
O/B
G
Y1
Y2
W1
W2
RH
RC
HVAC SYSTEM
1 AMP
1 AMP
1 AMP
SPARE SYSTEM RH
SYSTEM RC
RH-RC
JUMPER
O/B
G
Y1
Y2
W1
W2
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
4 AMP
PC BOARD
HP HC SYSTEM
B O REV VALVE
3 ZONES OFF MINIMUM
2 ZONES OFF CALLS
ON OFF
ECONO
SPEED
UP
MODE
STATUS HEAT COOL
DAS ACTIVE
OCCUPIED
HEAT
AUTO
COOL
CLOCK
POWER
CLOCK
CONTACTS
NIGHT
STAT
1. 24 VOLT SYSTEM POWER TERMINALS
2. ZONE TERMINALS 14-20
3. 24 VOLT POWER TERMINALS FOR OPTIONAL TIME CLOCK
4. TIME CLOCK CONTACT TERMINALS (REMOVE FACTORY JUMPER
WHEN WIRING CLOCK CONTACTS. N.C. = OCCUPIED MODE)
5. NIGHT THERMOSTAT TERMINALS
6. ECONOMIZER TERMINALS
(CONTACTS CLOSED IN OCCUPIED MODE)
7. DISCHARGE AIR SENSOR TERMINALS
8. HVAC SYSTEM TERMINALS
9. RH-RC JUMPER
10. 1 AMP HVAC CONTROL SYSTEM FUSES
11. 1 AMP SPARE FUSE
12. SYSTEM SET-UP SLIDE SWITCHES
13. TIME DELAY SPEED UP BUTTON
14. HEAT/AUTO/COOL SELECTOR SWITCH
15. MICROPROCESSOR STATUS LED
16. HEAT/COOL MODE STATUS LEDs
17. ZONE TERMINALS 1-13
18. 4 AMP PC BOARD FUSE

SC-Z20 PANEL TIME DELAYS
FUNCTION NORMAL MODE SPEED UP MODE
MINIMUM TIME IN HEAT OR COOL MODE 15 MINUTES 60 SECONDS
(Once the system is in the heat or cool mode,
it will remain there for a minimum of 15
minutes. The equipment may or may not be
on during this period)
MINIMUM OFF TIME REQUIRED BEFORE 5 MINUTES 20 SECONDS
THE EQUIPMENT CAN SWITCH FROM
HEAT OR COOL MODE
TIME BETWEEN STAGES (UP-STAGING) 10 MINUTES 40 SECONDS
EQUIPMENT MINIMUM ON/OFF TIME 5 MINUTES 20 SECONDS
FAN RUN TIME AFTER CLOCK 5 MINUTES 20 SECONDS
CONTACTS OPEN
SC-Z20 SYSTEM STATUS LED DEFINITIONS AND FUNCTIONS
Time Delay Speed - Up RED BLINKS when time delays are in speed up mode
Discharge Air Sensor GREEN ON when DAS is connected
BLINKS when 1st stage heat or cool go out
on limit
Status GREEN BLINKS to confirm microprocessor operation
Zones (1-20) RED (Heat) ON when there is a call for heating
GREEN (Cool) ON when there is a call for cooling
HVAC System
W1 GREEN ON when first stage heat is energized
W2 GREEN ON when second stage heat is energized
Y1 GREEN ON when first stage cooling is energized
Y2 GREEN ON when second stage cooling is energized
G GREEN ON when fan is energized
O/B GREEN ON when reversing valve is energized
Occupied GREEN ON when system is in occupied mode.
Mode RED (Heat) ON when system is in the heat mode
GREEN (Cool) ON when system is in the cooling mode
SYSTEM SET UP SWITCH DESIGNATIONS
HC Conventional Heat/Cool System
HP Heat Pump System
B Energizes the reversing valve on a call for heating
O Energizes the reversing valve on a call for cooling
2 ZONES Two zones must call to energize the equipment
3 ZONES Three zones must call to energize the equipment
(When both switches are OFF, the default is 1)
ON OFF
HP HC SYSTEM
B O REV VALVE
3 ZONE OFF MINIMUM
2 ZONES OFF CALLS
Speed Up Mode auto-resets after 15 minutes

SC-Z20
MODULATING ZONE CONTROL SYSTEM
PANEL LAYOUT
ZONE 13 ZONE 12 ZONE 11 ZONE 10 ZONE 9 ZONE 8 ZONE 7 ZONE 6 ZONE 5 ZONE 4 ZONE 3 ZONE 2 ZONE 1
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
ZONE 20 ZONE 19 ZONE 18 ZONE 17 ZONE 16 ZONE 15
R
C
NOT USED
R
C
T
T
NS
NS
E
E
DAS
DAS
O/B
G
Y1
Y2
W1
W2
RH
RC
1 AMP
1 AMP
1 AMP
SPARE SYSTEM RH
SYSTEM RC
RH-RC
JUMPER
O/B
G
Y1
Y2
W1
W2
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
4 AMP
PC BOARD
HP HC SYSTEM
B O REV VALVE
3 ZONES OFF MINIMUM
2 ZONES OFF CALLS
ON OFF
ECONO
SPEED
UP
MODE
TIME DELAYS
DIVIDED BY 15
STATUS HEAT COOL
DAS ACTIVE
OCCUPIED
HEAT
AUTO
COOL
SC-Z20 ‘E’ AND ‘E’ CONTACTS
CLOSE IN OCCUPIED MODE
DISCHARGE
AIR SENSOR
HEAT SETPOINT 140° F
COOL SETPOINT 54° F
24V 120V
R W2 W1 Y2 Y1 G 0/B
HVAC UNIT
WIRE TO ZONE DAMPER ACTUATOR
BOARD TERMINALS (R, C, Y, W)
TYPICAL OF ALL
ZONES
24 VOLT
75VA
TRANSFORMER
WIRE TO ZONE DAMPER ACTUATOR
BOARD TERMINALS (R, C, Y, W)
TYPICAL OF ALL
ZONES
Optional
SC-Z20-S1
Remote
Sensor
Terminals
PLACE JUMPER ACROSS
‘R’ AND ‘T’ TERMINALS
SC-Z20-NS
NIGHT STAT
S2 SC S1 O/B
AUX AUX
Y1 Y2 W1 GRC
Jackson Systems, LLC
www.jacksonsystems.com
WIRE
ACCESS
HOLE
BATTERY
COMPARTMENT
MOUNTING HOLES
MOUNTING HOLES
W2 MOUNTING
HOLE

SC-Z20-T MODULATING OR TWO-POSITION
ZONE THERMOSTAT WITH AUTO CHANGEOVER
C 24 VAC (Common)
R 24 VAC (Hot)
PO Power Open
PC Power Close
DS Duct Sensor
Y Cooling Relay
W Heating Relay
A / B Modbus Communications
TERMINAL DESIGNATIONS
KEY FUNCTIONS
ON/OFF KEY - When the SC-Z20-T is not
locked, this key allows the thermostat to be
turned ON or OFF. When in the OFF position,
the damper is also driven closed
STATUS KEY - Pressing the STATUS key
displays the UNIT number, ZONE number,
DUCT temperature and DAMPER position.
UP/DOWN KEYS - These keys are used to
increase or decrease the setpoint as well as
change thermostat setup values.
ENTER KEY - This key is used to enter changes
as well as exit the setup menu. (Refer to
Installation/Operation Manual for complete
setup instruction)
OPERATION
The duct sensor wired to the SC-Z20-T is
designed to select the mode of operation of the
damper. If the discharge air temperature is
above 72° F, the damper will open on a call for
heating. If the discharge air temperature is
below 72° F, the damper will open on a call for
cooling
DISASSEMBLING THERMOSTAT
Insert a small, flat-bladed screw driver in the
release slot located on the bottom of the
thermostat and pry straight up and away
from the subbase. Avoid twisting the case
as this may stress the LCD and cause it to
crack or bend the wiring terminal connection
pins.
SWITCH FUNCTIONS
There are eight dip switches located on the
thermostat PC board. Only dip switches 1, 2
and 3 are active.
SWITCH 1 - When Switch 1 is set to the ON
position, the thermostat is locked as
indicated by a padlock icon shown on the
LCD. When locked, only setpoint changes
and status functions can be accessed by
the user. Do not set Switch 1 in the ON
position until all SETUP functions are
completed.
SWITCH 2 - Switch 2 is used to display the
space temperature and setpoint in Celsius
(ON position) or Fahrenheit (OFF position).
Select Celsius or Fahrenheit before
proceeding to the thermostat SETUP menu.
SWITCH 3 - Switch 3 is used to select two-
position (ON) or fully modulating (OFF)
damper control to best suit the specific
application requirement.
FACTORY DEFAULT SETTINGS
Minimum Heating Damper Position 10%
Minimum Cooling Damper Position 10%
Maximum Damper Position 100%
Unit Number 00
Zone Number 00
Heating Limit 76° F
Cooling Limit 68° F
Actuator Speed 90
Modbus Address 01
Temperature Calibration Offset 0

OPERATION SEQUENCE:
When the room temperature is 1.5 degrees below setpoint the thermostat will close the R to W contacts on the
actuator board and signal the SC-Z20 panel that there is a heating call.
When the room temperature is 1.5 degrees above the setpoint the thermostat will close the R to Y contacts on
the actuator board and signal the SC-Z20 panel that there is a cooling call.
DAMPER NOTES:
To balance the HVAC system, unlock the thermostat by setting slide switch 1 to the OFF position. Press and
hold the SETUP key until the word DAMPER appears on the LCD. Press the UP or DOWN key until the word
OPEN appears on the LCD and then press the ENTER key. The damper will drive open. After balancing, the
thermostat must be set for normal damper operation. Using the above steps, press the UP or DOWN key until
only the word DAMPER appears on the LCD and then press the ENTER key.
The actuator board is located on the side of the damper actuator and is wired at the factory.
Each zone damper requires 2VA.
The space thermostat will control up to 12 damper actuators wired in parallel.
If the discharge air temperature at the damper is warmer than 72 degrees, the damper will open on a call for
heating..
If the discharge air temperature at the damper is below 72 degrees, the zone damper will open on a call for
cooling.
SC-Z20 PANEL NOTES:
Use standard 18 gauge thermostat wire.
Run four wire cable from the panel terminals (R, C, Y, W) to each individual zone damper actuator board.
Panel requires a separate 24VAC transformer with proper VA rating.
Locate discharge air sensor 3 feet down stream in trunk line.
Time Delay Speed Up Button shortens all the time delays on the control panel (use for testing only).
Minimum Call Selector Switches determine the number of zones that must be calling in order for the system to
bring on the heating or cooling equipment.
Time clock contacts are closed during occupied cycle.
SC-Z20-T MODULATING OR TWO-POSITION
ZONE THERMOSTAT
PO
PC
W
R
C
DS
DS
Y
1
2
3
4
5
6
7
8
C
R
R
Y
W
1
2
3
4
5
ACTUATOR
BOARD
DAMPER OR
DIFFUSER
ACTUATOR
90 SECOND TIMING
90° STROKE
44 lb.-in.
2VA
DAMPER OPEN (24VAC)
DAMPER CLOSED
(24VAC)
CALL FOR HEAT (24VAC)
24VAC POWER (HOT)
24VAC POWER (COM.)
DUCT SENSOR
DUCT SENSOR
CALL FOR COOL (24VAC)
(10K OHMS @77°)
OPEN
CLOSED
COM.
DS
DS
HEAT
COOL
WIRE TO
OPTIONAL
SLAVE
DAMPER
(UP TO 12 MAY BE WIRED
IN PARALLEL)
SC-Z20-T
AUTO CHANGEOVER
SPACE THERMOSTAT
R TO W CONTACTS CLOSE
ON A CALL FOR HEAT.
R TO Y CONTACTS CLOSE
ON A CALL FOR COOL
C R Y W
WIRE TO SC-Z20
ZONE PANEL TERMINALS
FACTORY JUMPER
RED LED
INDICATES
A CALL FOR
HEATING
GREEN LED
INDICATES
A CALL FOR
COOLING
DUCT SENSOR
COM
OPEN
CLOSE

SYSTEM NOTES:
Use standard 18 gauge thermostat wire.
Actuator requires a 24VAC 40VA transformer.
Option 2: Sensor can be relocated after the electric duct heater. RY1 relay coil can be wired to terminals
Option 1: RY1 can be used to bring on electric heat and drive damper open without relocating sensor. A 15K Ohm
PO
PC
W
R
C
DS
DS
Y
1
2
3
4
5
6
7
8
C
R
R
Y
W
1
2
3
4
5
ACTUATOR
BOARD
DAMPER OR
DIFFUSER
ACTUATOR
90 SECOND TIMING
90° STROKE
44 lb.-in.
2VA
DAMPER OPEN (24VAC)
DAMPER CLOSED (24VAC)
CALL FOR HEAT (24VAC)
24VAC POWER (HOT)
24VAC POWER (COM.)
DUCT SENSOR
DUCT SENSOR
CALL FOR COOL (24VAC)
DUCT SENSOR
(10K OHMS @77°)
OPEN
CLOSED
COM.
DS
DS
HEAT
COOL
WIRE TO
OPTIONAL
SLAVE
DAMPER
(UP TO 20 MAY BE WIRED
IN PARALLEL)
SC-Z20-T
AUTO CHANGEOVER
SPACE THERMOSTAT
FACTORY JUMPER
RED LED
INDICATES
A CALL FOR
HEATING
GREEN LED
INDICATES
A CALL FOR
COOLING
OPTION 1
resistor must be wired to the relay contacts so that when the relay is energized, the resistor will be in parallel with
the duct sensor. This will change the ohms value translating to a higher duct temperature which will drive the damper
open.
NC C NO
RY1
RELAY
24 V
COIL
15K Ohm Resistor
SC-Z20-T MODULATING OR TWO-POSITION
ZONE THERMOSTAT
WIRE TO SC-Z20
ZONE PANEL TERMINALS
3 and 5 on the actuator board. Relay contacts are wired in series with the duct heater coil.
OPTION 2
NC C NO
RY1
RELAY
24 V
COIL
WIRE TO DUCT HEATER COIL
5 3
WIRING DIAGRAM FOR ZONE HAVING AN ELECTRIC DUCT HEATER
COM
OPEN
CLOSE

R
C
T
T
NS
NS
SC-Z20-NS PROGRAMMABLE NIGHT STAT
WIRING DIAGRAM
ZONE 13 ZONE 12 ZONE 11 ZONE 10 ZONE 9 ZONE 8 ZONE 7 ZONE 6 ZONE 5 ZONE 4 ZONE 3 ZONE 2 ZONE 1
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
R
C
Y
W
ZONE 20 ZONE 19 ZONE 18 ZONE 17 ZONE 16 ZONE 15
R
C
NOT USED
E
E
DAS
DAS
O/B
G
Y1
Y2
W1
W2
RH
RC
1 AMP
1 AMP
1 AMP
SPARE SYSTEM RH
SYSTEM RC
RH-RC
JUMPER
O/B
G
Y1
Y2
W1
W2
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
COOL
HEAT
4 AMP
PC BOARD
HP HC SYSTEM
B O REV VALVE
3 ZONES OFF MINIMUM
2 ZONES OFF CALLS
ON OFF
ECONO
SPEED
UP
MODE
TIME DELAYS
DIVIDED BY 15
STATUS HEAT COOL
DAS ACTIVE
OCCUPIED
HEAT
AUTO
COOL
OVERVIEW:
The SC-Z20-NS programmable touchscreen thermostat can be used for occupied and unoccupied scheduling of the SC-Z20.
When wired and configured properly, the thermostat takes the place of a separate 7-day clock, night stat and override timer. The
SC-Z20-NS Programmable Fan option is used to trigger the ‘G’ fan relay to open or close the Clock Contact ‘T’ terminals on the
SC-Z20 panel that places the system in the occupied or unoccupied mode of operation. The thermostat can also be used with a
SC-T32-S1 Indoor Remote Sensor. 24 volt power to the thermostat is supplied by the SC-Z20 panel through dedicated Clock
Power terminals ‘R’ and ‘C’. The thermostat also has battery backup to maintain the real-time clock in the event of a power failure.
The thermostat can be configured to provide 7-day scheduling with 2 or 4 events per day. For commercial schedules, 2 events per
day is typical.
WIRING:
Wiring the SC-Z20-NS to the SC-Z20 panel only requires 18 gauge thermostat wire. (See diagram) Wire the thermostat ‘C’ terminal
to the Clock Power ‘C’ terminal on the SC-Z20 panel. Wire the thermostat ‘R’ terminal to the Clock Power ‘R’ terminal on the SC-
Z20 panel. Jumper the ‘R’ terminal on the panel to one of the Clock Contacts ‘T’ terminals. Wire the thermostat ‘G’ terminal to the
other Clock Contacts ‘T’ terminal. If an optional SC-T32-S1 remote sensor is used, use separate 18-2 wire and wire the sensor to
the ‘SC’ and ‘S1” terminals on the thermostat. (Polarity does not matter) Maximum wire distance between thermostat and sensor is
200 feet.
Optional
SC-T32-S1
Remote
Sensor
Terminals
PLACE JUMPER ACROSS
‘R’ AND ‘T’ TERMINALS
SC-Z20-NS
NIGHT STAT
S2 SC S1 O/B
AUX AUX
Y1 Y2 W1 GRC
Jackson Systems, LLC
www.jacksonsystems.com
WIRE
ACCESS
HOLE
BATTERY
COMPARTMENT
MOUNTING HOLES
MOUNTING HOLES
W2 MOUNTING
HOLE

SC-Z20-NS PROGRAMMING INSTRUCTIONS
HOW IT WORKS:
The SC-Z20-NS does not control the HVAC equipment and only uses the ‘G’ fan relay to put the SC-Z20 panel in either the
occupied or unoccupied mode. This is accomplished by using the Programmable Fan option so that the fan relay is energized
during occupied mode (Always On) and de-energized during unoccupied mode (Automatic). When in Automatic mode, the fan
relay will only energize when the temperature rises above or falls below the programmed unoccupied heating and cooling
setpoints.
RECOMMENDED SETUP:
Refer to the Installation Instructions to configure the thermostat. Leave all other setup menu items not shown below in factory
default.
SYSTEM SWITCH SETTINGS:
The SC-Z20-NS contains a set of four system switches located on the thermostat printed circuit board. Make sure the system
switches are set as follows:
Sw 1 = OFF
Sw 2 = ON
Sw 3 = OFF
Sw 4 = OFF
INSTALLER SETUP MENU CHANGES:
After the thermostat is powered up, touch and hold both the and section for 5 second to enter the Installer Menu.Clock Mode
Touch to advance forward through the menu or touch to backup.Mode Fan
MENU CHANGES: (LEAVE ALL OTHER OPTIONS AT FACTORY DEFAULTS)
02 = 2 (2 schedules per day)
04 = 1 (Programmable Fan)
After the above changes have been made, touch and hold until the thermostat exits the Installer Setup menu.Mode
SETTING THE CLOCK AND DAY OF WEEK:
It is important that the time of day and day of the week is set properly so that occupied and unoccupied programs start on time.
1. Touch the until the day of the week flashes. Tap the or arrow to select the day of the week.Clock UP DOWN
2. Touch again and the hour will flash. Tap the or arrow to select the correct hour. Note: PM hours are indicatedClock UP DOWN
by on the LCD.PM
3. Touch again and the minutes will flash. Tap the or arrow to select the correct minutes.Clock UP Down
4. To exit the menu, touch again.Clock
DAYLIGHT SAVING TIME:
Refer to the User Manual and DST Chart for Daylight Saving Time option.
PROGRAMMING EVENTS:
When the thermostat is configured to provide 2 schedules per day (Occupied/Unoccupied), 7 day per week, each event is
displayed on the LCD as (Occupied) and (Unoccupied).DAY NIGHT
1. Touch until (Monday) flashes.Program Mon
2. Tap again until the hour flashes and is displayed on the LCD. Use the or arrow to set the hour startProgram Day UP DOWN
time. Note: PM hours are indicated by on the LCD.PM
3. Tap again until the minutes flash. Use the or arrow to set the minutes.Program UP DOWN
4. Tap again and the heating setpoint will flash. Leave the setpoint at the factory default of 70 degrees.Program
5. Tap again and the cooling setpoint will flash. Leave the setpoint at the factory default of 75 degrees.Program
6. Tap again and the fan option will flash. This is the correct setting for the Day mode. If not, use the orProgram Always On UP
DOWN arrow to set the fan option from Automatic to Always On.

7. Tap again until the hour flashes and is displayed on the LCD. Use the or arrow to set the hour startProgram Night UP DOWN
time. Note: PM hours are indicated by on the LCD.PM
8. Tap again until the minutes flash. Use the or arrow to set the minutes.Program UP DOWN
9. Tap again and the heating setpoint will flash. You can use the or arrow to change the heating setpoint orProgram UP DOWN
use the factory default of 62 degrees.
10. Tap again and the cooling setpoint will flash. You can use the or arrow to change the cooling setpoint orProgram UP DOWN
use the factory default of 83 degrees.
11. Tap again and the fan option will flash. This is the correct setting for the Night mode. If not, use the orProgram Automatic UP
arrow to set the fan option from Always On to Automatic.DOWN
12. Tap again and (Copy) will appear on the LCD. If you wish to copy the Monday program to additional days of theProgram CPY
week, use the or arrow to add additional days. Example:UP DOWN Mon Tue Wed Thu Fri
13. Once you have selected the days to be copied, touch . will begin to flash and then the next programming day willProgram CPY
flash. Example: If you copy the Monday schedule through Friday, (Saturday) will flash. Simply repeat the programmingSat
steps for any day where the building will be unoccupied. The only required change is that both the and fan optionDay Night
should be set to and the heating and cooling setpoints for should reflect the unoccupied setpoints for .Automatic Day Night
14. Once programming is completed, make sure the thermostat is set in the mode of operation.Auto
TYPICAL 7-DAY SCHEDULE HAVING 2 EVENTS PER DAY WITH SATURDAY/SUNDAY UNOCCUPIED
PROGRAM DAY START TIME HEAT COOL FAN
SETPOINT SETPOINT
DAY MON 7:00 AM 70 75 Always On
NIGHT 5:00 PM 62 83 Automatic
COPY MONDAY PROGRAM TO TUESDAY, WEDNESDAY, THURSDAY AND FRIDAY
DAY SAT 7:00 PM 62 83 Automatic
NIGHT 5:00 PM 62 83 Automatic
COPY SATURDAY PROGRAM TO SUNDAY

SC-Z20
DESIGN AND INSTALLATION NOTES
• Extra consideration should be given when applying any zone control system to a building that
requires large amounts of cooling in the core zones during cold weather. Consider adding
auxiliary heat to external zones or using one system for the core zones and one system for the
external zones.
• It is recommended that the system installation be limited to 50 tons of capacity. Rooftop units
with economizers and relief dampers are strongly recommended for buildings with core
cooling loads.
• Over-sizing of the HVAC equipment is not recommended. In most cases, it is better to slightly
undersize the equipment.
• It is recommended that the HVAC equipment have two stages of heating and two stages of
cooling.
• The pressure drop through the zone dampers is negligible and should not be a factor when
sizing branch duct runs.
• Zone dampers are rated up to 2” w.c. of static pressure and up to 2,000 fpm.
• Zone dampers should be installed as far back from discharge air grille as possible. Flex duct
should be used for the last 5 feet of each branch run.
• Bypass dampers should be sized for 90% of the total system air flow at 2,500 fpm.
• The SC-Z20 panel should be located near the center of the building to keep
wire runs as short as possible.
• DO NOT mount the SC-Z20 panel on or inside the rooftop unit.
• Use a separate 24 VAC, rated at the proper VA transformer for the SC-Z20 panel.
• All wiring should be 18 gauge standard or plenum rated thermostat wire.
• Wiring should comply with all local and national codes.

SC-Z20
WIRING DETAILS
GENERAL NOTES
Install the SC-Z20 control panel on a flat surface near the HVAC equipment. The panel should be installed in a dry, clean
location approximately 60 inches from the floor. Do not install the control panel on or inside a rooftop unit.
24 VOLT POWER
The control panel requires a 24 Volt transformer with a proper VA rating. Do not power the control panel from the
transformer in the HVAC equipment. Connect 24 Volts to the terminals labeled on the interface24 VAC INPUT POWER
board. 18-2 thermostat wire is recommended.
DISCHARGE AIR TEMPERATURE SENSOR
The control panel requires a discharge air temperature sensor. Mount the sensor 26 inches from the HVAC equipment in
the supply duct. Connect the sensor to the terminals labeled on the interface board. 18-2 thermostat wire isDAS
recommended.
HVAC UNIT
The control panel is wired to the HVAC equipment in the same way as a standard 2-stage heat / 2-stage cool thermostat.
Connect the HVAC equipment to the terminals labeled on the interface board. 18-8 thermostat wire isHVAC SYSTEM
recommended.
R, C, Y, AND W ZONE DAMPER TERMINALS
The control panel requires a heating and cooling contact closure from each zone damper. Connect terminals , , , andRCY
WRC,YWfrom each zone damper to the terminals labeled , , and on the interface board. 18-4 thermostat wire is
recommended.
SC-Z20-NS PROGRAMMABLE NIGHT STAT (OPTIONAL)
The control panel has an optional input for a SC-Z20-NS programmable night stat. To install the thermostat, remove the
factory installed jumper between the two terminals labeled and and wire the jumper across terminals and . Refer toTT RT
the SC-Z20-NS wiring and programming instructions in this manual.
MINIMUM CALLS SELECTION SWITCHES
The control panel is equipped with two selector switches located on the interface board. When bothMinimum Calls
switches are in the OFF position, any zone calling can bring on the equipment. When the switch is in the ON2 ZONES
position, at least two zones have to call to bring on the equipment. When the switch is in the ON position, at least3 ZONES
three zones have to call to bring on the equipment. If both and switches are in the ON position, the2 ZONES 3 ZONES
default is three.
TIME DELAY SPEED UP BUTTON
The control panel is equipped with a time delay speed up button. When the speed up button is engaged the time delays
between stages and between modes of operation are divided by 15. The time delay speed up mode will reset after fifteen
minutes. Time delay speed up should only be used for start up and service.

SC-Z20 COMFORT SYSTEM™
CONTROL PANEL SPECIFICATIONS
APPLICATION:
The model SC-Z20 is a commercial zone control system that allows a single heating and cooling unit to have up to 20
individual zones. Each zone is controlled by its own space thermostat and motorized damper. If a majority of zones are
calling for heat, the system will operate in the heating mode. The two stages of heat will be cycled to maintain the heating
discharge air setpoint. If a majority of zones are calling for cooling, the system will operate in the cooling mode and the two
stages of cooling will be cycled to maintain the cooling discharge air setpoint. If the number of zones calling for heating and
cooling are equal, the system will operate in the cooling mode first. This is known as Cooling Priority. Each zone damper or
diffuser will modulate, based on zone and discharge air temperature, to maintain the individual zone temperature setpoint.
Abarometric or electronic bypass damper will modulate to maintain the duct static pressure.
DIMENSIONS:
Height: 13.5”
Width: 11.0”
Depth: 2.0”
PANEL CONSTRUCTION:
Rating: NEMA1
Material #18 aluminum with 4 knock-outs on top (open bottom)
Door: Fully removable, self-centering
Finish: Blue anodized
POWER REQUIREMENTS:
Voltage: 24 VAC
VA: 2 VA per individual zone damper actuator
Dampers / Diffusers - 2 VA Each
OPERATING AMBIENT:
Temperature: 32°F to 120°F
SHIPPING WEIGHT:
Panel Weight: 10.0 lbs.
WARRANTY:
Panel: 5 Years

SC-Z20
SPECIFICATION SUGGESTIONS
1.01 ZONE CONTROL SYSTEMS
A. l. Provide a SC-Z20 zone control system manufactured by Specified ControlsGenera
to meet the performance as specified in this section. Each zone control system shall
meet the following requirements.
1. The zone control system shall be composed of one logic panel, up to 20 zone
dampers with actuators, zone thermostats, and bypass damper(s).
2. The zone control system shall be capable of controlling up to 20 zones and
must use proprietary fully modulating thermostats.
3. The system shall have auto changeover and be capable of controlling two
stages of heat and two stages of cooling. The system shall also be
compatible with heat pump systems.
4. The zone control system shall require any field programming. Anot
laptop computer or service tool shall be required for setup andnot
troubleshooting.
B. . The zone control panel shall be suitable for the indoor ambientEnvironment
conditions and shall be rated for operation between 32°F and 120° F.
C. . Provide diagnostic LEDs for heating stages, cooling stages, fan,Serviceability
and the heating or cooling request of each zone.
D. . The zone control system shall require a battery back-up.No battery back-up not
E. . The zone control system shall be able to operatePower and Immunity to noise
between 90% and 110% of nominal voltage rating and shall not be affected by
radio frequency interference (RFI).
1.02 ZONE DAMPERS
A. Zone dampers shall be round, rectangular or VAV diffuser type. Round dampers
shall have a diameter of 6 inch to 36 inch. Rectangular dampers shall have a
minimum size of 8 inch by 8 inch. VAV diffusers shall have an inlet size of
6 inch to 14 inch.
1. . 18 gauge (minimum) galvanized steel.Frames
2. . 18 gauge (minimum) galvanized steel.Blades
3. . Oil impregnated sintered iron bushings.Bearings

SC-Z20
SPECIFICATION SUGGESTIONS
4. . EDPM seal installed on inside of round damperSeals for Round Dampers
shell. Leakage shall be less than 2% at 3 inches of static pressure.
5. Dampers shall be Specified Controls ZD-XX, ZD-XXXX or approved equal.
6. VAV Diffusers shall be Specified Controls VD-XX or approved equal.
7. All zone dampers to have minimum position adjustments.
1.03 ELECTRIC DAMPER ACTUATORS AND ACTUATOR CONTROL BOARDS
A. . All zone damper actuators shallModulating and two position damper actuators
have sufficient reserve power to provide smooth action as specified.
1. Damper actuators shall be capable of turning clockwise or counterclockwise
and be powered by a reversible motor which is connected to the output shaft.
2. All actuators shall be factory wired to the damper control board.
3. All damper actuators shall be mounted outside of the air stream.
B. The damper actuator control board shall provide wiring terminals for all field and
factory wiring. The damper actuator board will also provide an output for
auxiliary zone heat.
1. . Damper actuator and duct sensor.Factory Wiring
2. . Zone thermostat, wiring to system panel, andField Wiring
optional auxiliary heat.
1.04 BYPASS DAMPERS
A. Bypass damper(s) shall be provided to maintain the proper duct static pressure.
1. The bypass damper(s) shall be round or rectangular.
2. Systems under 0.75” w.c. of static pressure shall use a barometric
bypass damper.
3. Systems 0.75” w.c. and over of static pressure shall use an electronic
bypass damper with static pressure controller.
4. The bypass damper(s) shall be sized for 90% of the total air flow at
2500 FPM.

SC-Z20
SPECIFICATION SUGGESTIONS
1.05 WIRING
A. .Control Wiring
1. All control wiring shall be 24 Volts or less.
2. All control wiring shall be standard or plenum-rated thermostat wire.
18 gauge minimum. No shielded cable shall be required.
3. Control wire and cable shall be installed in accordance with NEC.
1.06 SERVICE AND GUARANTEE
A. . The entire zone control system shall be warranted for a period of five (5)General
years from date of installation. This includes the components only and does not
include labor of any kind.
SC-06-1267-051717