TABLE OF CONTENTS...................................................................................................................................................................Page
SYSTEM DESCRIPTION...........................................................................................................................................................................................1
Zone Dampers....................................................................................................................................................................................................5
Status Lights .......................................................................................................................................................................................6
Status Lights .......................................................................................................................................................................................9
Capacity Control and Staging............................................................................................................................................................11
LAT and OAS Installation ..................................................................................................................................................................12
Bypass Damper with Integrated Pressure Control.........................................................................................................................................21-22
Troubleshooting / Service Checks.....................................................................................................................................................................25
LAT Voltage – Temperature Conversion Chart..................................................................................................................................................25
The Digitract 4 zoning system enables up to four room thermostats to control a single HVAC system. This permits superior building temperature control
over a standard single thermostat. Any generic thermostat may be used on this control system. When using digital thermostats, they must have “C”
terminal for common or be battery powered. Both Programmable and Non-Programmable thermostats can be used. This system is designed to be
installed and serviced by qualified licensed professionals.
INTRODUCTION
SYSTEM DESCRIPTION
The Digitract 4 zoning system consists of a 2-stage System Controller
with built-in Capacity Control (leaving air sensor), Zone Dampers, Zone
Thermostats, Bypass Damper and Damper Transformer.
The System Controller is the heart of the Digitract 4 zoning system. It
monitors the leaving air temperature, zone thermostats and controls the
HVAC System and zone dampers. See pages 6 to 10 for further information.
trol feature of the System Controller. It is a sensor placed in the supply
air of the HVAC system. The sensor monitors the supply air temperature of the HVAC system and sends this information to the System
Controller. The System Controller uses this information to stage and temporarily cycle the HVAC system off if the leaving air gets too hot in heat
mode or too cold in cool mode. For heat pumps, this input is also
used to control the auxiliary heat. See Capacity Controller section, page
Balance Point is used for fossil fuel applications when an FOAS is
applied. The balance point feature will lock out compressor and enable
gas furnace when outside air temperature drops below BP (balance
point) setting.
The Zone Dampers are air valves placed in the forced air duct work
for each zone. They are controlled by the System Controller. While the
HVAC system is running, the zone dampers for any zone thermostats not
calling will close and zone dampers for the zones calling will remain
open. Conditioned air is only directed to the zones needing it. See pages
13 to 17 for further information.
The Zone Thermostats monitor the room temperature of each zone
and compare it to the heat and cool setpoints stored in them. If the room
temperature drops below the heat setpoint, the zone thermostat makes
a heat call telling the System Controller that zone needs heating. If the
room temperature rises above the cool setpoint, that thermostat makes
a cool call telling the System Controller that zone needs cooling.
Two-stage thermostats are not required with the Digitract 4 System. The
System Controller will cycle staging and auxiliary strip heat based on
The Bypass Damper is a pressure relief valve placed between the
supply and return ducts of the forced air duct work. As zone dampers
start closing, the bypass damper will open and divert some of the supply
air to the return. This prevents a pressure buildup in the supply duct
which can cause fan cavitation, excessive air velocities, and excessive
Damper Transformer. Wired to TR1 and TR2 on the System Controller.
Powers the zone dampers only. Requires an in-line fuse. See Damper
*The Digitract 4 was designed for both residential and
commercial applications of 4 or less zones. The full
spectrum of supply dampers can be applied, from low
pressure; medium pressure; and heavy duty; round and
rectangular.
System Controller
1
Leaving Air Sensor
2
ZONE 4
73
Zone Damper
3
Zone Thermostat
4
Bypass Damper
5
Damper
6
Transformer
The Leaving Air Sensor (LAT) is part of the staging and capacity con-
11, for further information.
ZONE 3
ZONE 2
ZONE 1
2
LAT
5
3
73
4
1
73
73
DIGITRACT 4
System Controller
6
Fused 24V Transformer
leaving air temperature and time.
zone damper blow-by. See pages 17 to 22 for further information.
Transformer section, page 23.
1
Digitract 4 COMPONENT SELECTION GUIDE
2
WIRING – GAS/ELECTRIC DTGE4A
Use minimum 18 gauge for all wiring.
All wiring must meet state and local codes.
Zone damper terminals. Refer to “Wiring – Zone Dampers” section, page 5.
Connect W2 and Y2 of the DTGE4A only if there are two heat and/or two cool stages.
Most thermostats are compatible with the DigiTract 4.
Zone damper terminals. Refer to “WIRING – ZONE DAMPERS” on page 5.
Install one 24V AC transformer, sized and fused for the total number of zone dampers. See “DAMPER
Fan cycling jumper: Bottom position = FAU fan control; Upper position = energized fan on heat call (JPI not used)
Adjustable potentiometers:
• HI – To establish HI cutout for furnace protection and staging temperatures – must be field adjusted to 120°
for HP applications.
• LO – To establish LO cutout, to protect freezing of coil, to set up staging for compressors
• TIME – To establish changeover time when opposite calls will be recognized by controller
Digitract 4 Gas/Electric 2-Stage Heat/Cool
HVAC unit and LAT terminals. Do not connect Y2 or W2 for single stage heat/cool systems.
BYPASS
DAMPER
LAT
SENSOR
1
ON
OFF
S
LAT
}
S
Y2
W1
G
W2
Y1
R
C
UNIT TERMINALS
AIRFLOW
2
Y2
W1
G
W2
Y1
R
C
W R Y G C
3
ZONE 1
THERMOSTAT
LAT. Locate the leaving air sensor in the supply air stream, as far from the coil/heat exchanger as possible
1
before the bypass takeoff. Do not locate the LAT downstream of the bypass takeoff. Refer to "CAPACITY
Zonex DigiTract GE
6
JP1
R11
Y1GW1Y2W2
STAT 1STAT 2
W R Y G CW R Y G CW R Y G C
W R Y G C
ZONE 2
THERMOSTAT
JP2
PWR
DTGE4A
W R Y G C
ZONE 3
THERMOSTAT
40
STAT 3
7
135
45
125
50
115
LO HI
15
10
145
25
155
5
TIME
3
DPR 1
DPR 2
DPR 3
DPR 4
STAT 4
W R Y G CW R Y G C
ZONE 4
THERMOSTAT
20
CONTROLLER-LAT INSTALLATION” on page 12 for further information.
DAMPER
1
1
2
2
3
3
4
4
TR1
TR2
4
24V AC Transformer
to Power Dampers
5
2
3
4
5
TRANSFORMER” on page 23.
6
7
3
WIRING – HEAT PUMP DTHP4A
1
2
3
4
5
6
7
8
Digitract 4 HP 3-Stage Heat/2-Stage Cool
Connect W2 from the controller to the unit’s electric heat stage terminal designation. It is recommended to install an outdoor thermostat
for non-fossil fuel applications.
Most heat pump thermostats are compatible; 1C/2H.
NOTE: Some combination thermostats do not have an E terminal. Connect W2 of the thermostat to the E terminal of STAT 1 terminal block.
Zone damper terminals. Refer to “WIRING – ZONE DAMPERS” on page 5.
Reversing valve jumper:
Fossil fuel jumper:
Fan jumper:
FOAS – Outdoor Air Sensor used to sense Balance Point temperature for auto-changeover, fossil fuel application only. Use FOAS only; not
HP outdoor thermostat.
Adjustable potentiometers:
• BP – To establish temperature that locks out heat pump and energizes fossil fuel furnace
• HI – To establish HI cutout for furnace protection and staging temperatures
• LO – To establish LO cutout, to protect freezing of coil, to set up staging for compressors
• TIME – To establish changeover time when opposite calls will be recognized by controller
B-Mode –
energize for heat
O Mode –
energize for cool
Fossil Fuel Application
Not Used
Normal HP Operation
ON
Zonex DigiTract HP
OFF
LAT
}
Y 1GO/BY 2
STAT 1
E O/B R Y G C
BYPASS
DAMPER
AIRFLOW
LAT
SENSOR
Y2
O/B
G
W2
Y1
R
C
OAS
OAS
O/B
W2
+
–
+
–
Y2
G
Y1
R
C
S TAT 2
O/B FF
FAN
W 2
O/B R Y G CO/B R Y G C
S TAT 3
DTHP4A
33
45
40 50
25 41
LOBP
STAT 4
O/B R Y G C
120
115 125
HI
DPR 1
DPR 2
DPR 3
DPR 4
5 25
TIME
15
1
1
2
2
3
3
4
4
TR1
TR2
E O/B R Y G C
ZONE 1
THERMOSTAT
O/B R Y G C
ZONE 2
THERMOSTAT
O/B R Y G C
ZONE 3
THERMOSTAT
O/B R Y G C
ZONE 4
THERMOSTAT
24V AC Transformer
to Power Dampers
LAT. Locate the leaving air sensor between the refrigerant coil and the electric heat coil(s) or other auxiliary heat source. Refer to
“CAPACITY CONTROLLER – LAT INSTALLATION” page 12, for further information.
2
3
4
Install one 24V AC transformer, sized and fused for the total number of zone dampers. See “DAMPER TRANSFORMER” on page 23.
5
6
7
8
4
WIRING – ZONE DAMPERS
There are three methods of wiring the zone dampers. If necessary, you
can mix wiring methods on different zones to suit your application.
Method 1: When wiring one to three TR/TREC series dampers to
a zone.
Method 2: When wiring more than three TR/TREC series dampers to a
zone, use a 24V ac, SPNO relay.
Method 3: When using 101AMPD or 101CD series dampers with a
DigiTract controller. Note: 101 series medium pressure dampers are
required for all systems over 5 tons. Refer to Parts Selection Table,
page 13.
5
The DigiTract Controller is the heart of the DigiTract zoning system. It
is an auto changeover, home run system with a built in staging and
capacity controller. The function of the system controller is to receive
calls from the zone thermostats, operate the HVAC system in either heat
or cool mode and close the damper(s)of zones not calling for the operating mode. The mode of operation is determined by the first call
received. If the thermostats are calling for opposite modes, a
changeover sequence will start. Based on the Time Setpoint setting, a
changeover will occur after time delay. Changeover will continue as long
as there are opposing calls. The built in Capacity Controller maintains
the supply air temperature within an operation range to prevent freeze
ups and overheating. For Heat Pumps, the DTHP4A System Controller
will also control the auxiliary heat.
The Digitract 4 controller is not to be subjected to temperatures below
33°F or above 160°F. The controllers must not be installed in atmospheres that could create condensation or corrosion. Warranty is voided
on controllers that fail due to moisture or corrosion evidenced on the
circuit board. The operating voltage range on the Digitract 4 controllers
is 24 vac to 28 vac.
The DigiTract 4 is available in two models, Gas Electric 2-Stage
Heat/Cool and Heat Pump 3 stage Heat/2 Stage Cool with integrated fossil
fuel control.
NOTE: For Heat Pump systems using gas electric inputs (no “O” or “B”
reversing valve circuits) use the DTGE4A controller.
SYSTEM CONTROLLERS
SYSTEM CONTROLLER – GAS/ELECTRIC DTGE4A
OPERATION
The System Controller will initially run in the mode requested by the first
calling zone thermostat.
Cool mode – When running in the cool mode, the System Controller
energizes the compressor(s) and indoor blower. This is indicated by the
corresponding Y and G LEDs illuminating. Dampers for the zones not
calling for cool are powered closed and the dampers for the zones calling
for cool are left open. This is indicated by the DPR LEDs. If the DPR LED
is illuminated on the damper terminal strip and damper terminal board, the
corresponding damper is closed. The system will continue to run in the
cool mode until all calls are satisfied or changeover occurs. When all calls
are satisfied or prior to changeover, the system will go into a purge mode.
Heat mode – When running in the heat mode, the System Controller
energizes the heat stage (s), indicated by the W LEDs illuminating. If the
a call for heat, indicated by the G LED illuminating. Dampers for the
zones not calling for heat are powered closed and the dampers for the
zones calling for heat are left open. This is indicated by the DPR LEDs.
If a DPR LED is on, the corresponding damper to the LED is being
powered closed. The system will continue to run in the heat mode until
all calls are satisfied or changeover occurs. When all calls are satisfied
or prior to changeover, the system will go into purge mode.
Changeover – While the system is operating in one mode, and the
System Controller receives a call for the opposite mode, the System
Controller will continue to run in the current mode until the changeover
TIME limit has been reached, or all current calls have been satisfied.
Then the System Controller will go into a purge mode for 4 minutes,
then change over to the new mode
Purge mode – Purge mode is initiated after the last calling zone is
satisfied, or when the controller goes into a forced changeover. All HVAC
output LEDs on the controller go off during this cycle. When the last calling
zone thermostat satisfies, the Digitract controller goes into a four-minute
purge cycle. During this time delay all controller outputs to the HVAC
system and dampers are terminated. All dampers go to a full openp osition
and the HVAC system fan delay control runs the blower for a time. This
time delay with no control outputs allows the supply duct to return to
ambient temperature before the next call is initiated.
When the controller goes into a force mode changeover, and the initial call
drops out to the purge cycle, the HVAC outputs are terminated, and the initial zone damper remains open for a 4-minute delay with the other dampers
closing. The HVAC system fan control allows the blower to run for a time,
and the initial calling zone supply duct returns to ambient temperature.
Ventilation– When no zones are calling, all zone dampers are open.
During this time, if any thermostat has the fan switch ON then the indoor
blower is energized (G made to R) and the G LED is on. This provides
ventilation to all zones.
Fan Control Jumper is in the JP2 position, the blower will energize with
6
W1: First stage heat. When energized (W1 made to R),
energizes first-stage heat.
W2: Second stage heat. When energized (W2 made to R),
energizes second-stage heat.
G:Blower. When energized (G made to R),
energizes the indoor blower.
Y1: First stage cool. When energized (Y1 made to R),
energizes first stage cooling.
Y2: Second stage cool. When energized (Y2 made to R),
energizes second stage cooling.
R:HVAC unit 24V power. Powers the Digitract 4 board
and zone thermostats.
C:HVAC unit 24V power return.
B. Thermostat Terminals – Connects up to four zone
thermostats.
W: Heat call. When energized (W made to R),
requests the Digitract 4 to run in heat mode.
R:HVAC unit 24V power.
Y:Cool call. When energized (Y made to R),
requests the Digitract 4 to run in cool mode.
G:Blower Fan- When energized (G made to R), requests the
DigiTract 4 to turn on the indoor blower fan.
C:HVAC unit 24V common.
C. Damper Terminals – Connects dampers for up to four zones and
damper power supply.
TR1/TR2: 24V AC transformer terminals. This transformer powers
only the zone dampers.
1 1: Zone damper 1.
When energized, powers zone damper 1 closed.
2 2: Zone damper 2.
When energized, powers zone damper 2 closed.
3 3: Zone damper 3.
When energized, powers zone damper 3 closed.
4 4: Zone damper 4.
When energized, powers zone damper 4 closed.
D. Damper Status LEDs – On when corresponding zone damper is
being powered closed.
E. Board Number – This number indicates the circuit board number
and revision. You must know this number if conferring with technical support.
F. Special Function Jumpers
JP1 – Not used.
place the jumper over the top and middle jumper pins. Controller is shipped
with the jumper on the middle and lower pin for furnace fan control.
G. Microcontroller – Responsible for activation and control of the
unit based upon thermostat input.
H. HVAC System Status LEDs – Indicates what the DTGE4A is
energizing on the HVAC system.
Y1: Compressor, yellow. On when the first-stage cool is energized.
Y2: Compressor, yellow. On when the second-stage cool is energized.
G: Blower, green. On when the indoor blower is energized.
W1: Heat, red. On when first stage heat is energized.
W2: Heat, red. On when second stage heat is energized.
PWR: Power, orange. On when power at R and C and the Power
Switch is on. Flashing when in Capacity Control cut out mode.
See Status Lights section, page 6, for further information.
I. Power Switch – When OFF, power from the HVAC unit transformer is
disconnected from the Digitract 4 and thermostats. When ON, power
from the HVAC unit transformer is supplied to the Digitract 4 and the
zone thermostats.
J. Adjustable Potentiometers – For HIGH limit, LO limit and TIME
changeover. Use these potentiometers to adjust limits for a customized
job. From factory the settings are 145° high, 45° low and 15-minute
changeover.
SYSTEM CONTROLLER – GAS/ELECTRIC DTGE4A
COMPONENTS
A. HVAC Unit/LAT Terminals – Connects to HVAC unit
and Leaving Air Sensor (LAT).
S S: LAT terminals. The LAT monitors the leaving
air temperature.
J
15
135
Zonex DigiTract GE
ON
OFF
S
A
LAT
}
S
UNIT TERMINALS
Y2
W1
G
W2
Y1
R
C
STAT 1STAT 2
W R Y G C
ZONE 1
THERMOSTAT
JP2 – Electric Heat – To energize the system blower on a call for heat,
R11
Y1GW1Y2W2
W R Y G CW R Y G CW R Y G C
B
JP1
PWR
JP2
DTGE4A
H
F
45
E
50
40
LO
G
STAT 3
W R Y G CW R Y G C
ZONE 3
THERMOSTAT
125
115
HI
155
5
TIME
D
STAT 4
25
DPR 1
DPR 2
DPR 3
DPR 4
DAMPER
20
10
145
1
1
2
2
3
3
4
4
TR1
TR2
C
7
The System Controller will initially run in the mode requested by the first
calling zone thermostat.
Cool mode – When running in the cool mode, the System
Controller energizes the compressor(s), indoor blower
and energizes the reversing valve (O made to R) if the reversing valve selection jumper is in the O position. This is indicated
by the corresponding Y, G and O/B (if jumper in O position)
LEDs illuminating. Also, the dampers for the zones not calling
for cool are closed and the dampers for the zones calling for
cool are left open. This is indicated by the DPR LEDs. If the DPR
LED is illuminated, the damper terminal strip and damper terminal board, the corresponding damper is closed. The system
will continue to run in the cool mode until all calls are satisfied
or changeover occurs. When all calls are satisfied or prior to
changeover, the system will go into a purge mode.
Heat mode – When running in the heat mode, the System Controller
energizes the compressor(s), indoor blower and energizes the
reversing valve if the reversing valve selection jumper is in the B
position. This is indicated by the corresponding Y, G and O/B (if
jumper in B position) LEDs illuminating. Also, the dampers for the
zones not calling for heat are closed and the dampers for the zones
calling for heat are left open. This is indicated by the DPR LEDs. If the
DPR LED is on the damper terminal strip and damper terminal board,
the corresponding damper is closed. After running in heat mode for 8
minutes, the System Controller will energize the auxiliary heat if the coil
leaving air temperature drops below 90° and will de-energize when the
coil leaving air temperature rises above 100°. The W2 LED is on when the
auxiliary heat is energized. The system will continue to run in the heat
mode until all calls are satisfied or changeover occurs. When all calls
are satisfied or prior to changeover, the system will go into a purge mode.
Changeover – While the system is operating in one mode, if the System
Controller receives a call for the opposite mode, the System Controller
will continue to run in the current mode until the changeover time has
been reached or all current calls are satisfied. The System controller
will then go into a 4-minute purge, then change over to the opposite
mode.
Purge mode – Purge mode is initiated after the last calling zone is
satisfied, or when the controller goes into a forced changeover. All HVAC
output LEDs on the controller go off during this cycle. When the last
calling zone thermostat satisfies, the Digitract controller goes into a four
minute purge cycle. During this time delay all controller outputs to the
HVAC system and dampers are terminated. All dampers go to a full open
position and the HVAC system fan delay control runs the blower for a
time. This time delay with no control outputs allows the supply duct to
return to ambient temperature before the next call is initiated.
When the controller goes into a force mode changeover, and the initial
call drops out to the purge cycle, the HVAC outputs are terminated, and
the initial zone damper remains open for 4 minute delay with the other
dampers closing. The HVAC system fan control allows the blower to run
for a time, and the initial calling zone supply duct returns to ambient
temperature.
Auxiliary heat – 8 minutes after the System Controller has run in heat
mode, if the coil leaving air temperature is below 90°, the auxiliary heat
is energized and the W2 LED illuminates. When the coil leaving air
temperature rises above 100°, the auxiliary heat is de-energized and the
W2 LED cycles off.
Ventilation – When no zones are calling, all zone dampers are open.
During this time, if any thermostat has the fan switch ON then the
indoor blower is energized and the G LED is on. This provides
ventilation to all zones.
Emergency heat – Emergency Mode is selected from STAT1 position
only. To make an emergency heat call, STAT1 must be in the emergency
heat mode and make a heat call. When STAT1 places the call for heat, all
thermostats will then be able to place a call for emergency heat
independently. Compressors will be locked out of operation until STAT1
places a cool or heat call. When a call for emergency heat is placed the
blower and electric strip heat will energize. Zones that are not calling
for heat will close their dampers; those that are calling will remain open.
Fossil Fuel Operation – The DTHP4A provides a selectable integrated
Fossil Fuel operation. Applying this controller to Fossil Fuel systems
eliminates the need for a “Fossil Fuel Kit,” additional capacity control,
auxiliary relays and complicated control wiring. The controller offers
balance point control when the optional FOAS outdoor air sensor is used.
This enables the heat pump compressor to be locked out and the Furnace
to be energized on a call for heat, when the outdoor temperature is below
the BP setpoint on the DTHP4A controller. When the FOAS is not used, the
controller will stage up to the furnace based on time and temperature.
By placing the controller jumper in the FF position the controller is
configured for Fossil Fuel operation. When there is no Outside Air
Sensor applied, a call for heat from any zone energizes Y1 compressor
output and G blower output (“B” mode energizes rev valve also). With
the factory POT settings: LO 45° and HI 120°, the controller will stage up
from Y1 to Y2 after four minutes, if the supply air temperature is below
95°. After 8 minutes run time if the supply air temperature is 90° or
below, W2 LED will illuminate energizing the furnace; Y1 and Y2 will
drop out leaving the fan circuit energized. When the controller energizes
W2 for the furnace, the capacity control automatically implements a fixed
cutout temperature of approximately 135°. When this temperature is
exceeded, W2 drops out and the system goes into a 4-minute purge cycle
to reduce supply air temperature.
When using the optional FOAS Outdoor Air Sensor, the Balance Point “BP”
POT should be checked and adjusted as required; factory setting is 33°. On
call for heat, if the OA temp is above the BP setting, Y1 will be energized
on the Heat Pump. When the OA is below the BP, call for heat will
energize W2 gas furnace directly.
SYSTEM CONTROLLER – HEAT PUMP DTHP4A
OPERATION
8
STATUS LED LEGEND
COMPONENTS DTHP4A
SYSTEM CONTROLLER – HEAT PUMP DTHP4A
O/BReversing valve LED, yellow. On when the reversing valve is energized.
Y1Compressor LED, yellow. On when the first compressor stage is energized.
Y2Compressor LED, yellow. On when the second compressor stage is energized.
GIndoor blower LED, green. On when the indoor blower is energized by the DTHP4A Controller.
W2Auxiliary heat LED, red. On when the auxiliary heat is energized.
PWRPower LED, orange. On when DTHP4A is powered. Flashing during capacity control cutout.
DPRDamper status LED, red. One per damper. On when damper is closed.
STATUS LEDs
O/BY1Y2GW2PWRDPRMODEFUNCTION
OFFOFFOFFOFFOFFOFFOFFOffPower off.
OFFOFFOFFOFFOFFONOFFOnPower on, blower off, all zones satisfied.
ON/OFFOFFOFFONOFFON0VentBlower on, compressor(s) off, all zone dampers open.
ON/OFFOFFOFFOFFOFFON1PurgeBlower off, compressor(s) off. Dampers with LED on are closed.
AONOFFONOFFON1Y1 Cool1st stage cool, blower on. Dampers with LED on are closed.
AONONONOFFON1Y2 Cool2nd stage cool, blower on. Dampers with LED on are closed.
BONOFFONOFFON1Y1 Heat1st stage heat, blower on. Dampers with LED on are closed.
BONONONCON1Y2 Heat2nd stage heat, blower on. Dampers with LED on are closed.
ON/OFFOFFOFFONONON1Em. HeatAuxiliary and emergency heat on.
OFFOFFOFFONOFFFL1Cap Cut outBlower on, all compressors off. Dampers with LED on are closed.
ON/OFFONONONONON1Em. HeatIf below 90°, stages up to Y1, Y2 and W2
ON/OFFOFFOFFONONON1Em. HeatFossil fuel mode, stages up to W2 only
FL = Flashing A = On when reversing valve jumper is in O position B = On when reversing valve jumper is in B position
C = On when auxiliary heat is energized 1 = One or more damper LEDs on 0 = All damper LEDs are off
9
leaving air temperature.
±: OAS Optional Outside Air Sensor for use in Fossil Fuel /
Dual Fuel applications
W2: Auxiliary Heat. When energized (W2 made to R), turns on the
heat pump auxiliary heat.
G:Blower. When energized (G made to R), turns on the
indoor blower.
Y1: Compressor. When energized (Y1 made to R), turns on the heat
pump first stage compressor.
Y2: Compressor. When energized, (Y2 made to R), turns on the
heat pump second stage compressor.
O/B: Reversing Valve. When energized (O/B made to R), engages
the heat pump reversing valve.
R:Heat pump unit 24V power. Powers Digitract 4 and thermostats.
C:Heat pump unit 24V common.
B. Thermostat Terminals – Connects up to four zone heat pump
thermostats.
E: Emergency Heat. On STAT 1 only. Connected to E terminal on
STAT 1.
0/B: Reversing valve signal. “O” energizes reversing valve in the Cool
mode. “B” energizes reversing valve in the Heat mode.
R: Heat pump unit 24V power. See A.
Y: Compressor.
G: Blower.
C: Heat pump unit 24V common.
C. Damper Terminals – Connects dampers for up to four zones and
damper power supply.
TR1/TR2: 24V AC transformer terminals. This transformer powers
only the zone dampers.
1 1: Zone damper 1. When energized, powers zone damper 1 closed.
2 2: Zone damper 2. When energized, powers zone damper 2 closed.
3 3: Zone damper 3. When energized, powers zone damper 3 closed.
4 4: Zone damper 4. When energized, powers zone damper 4 closed.
D. Damper Status Lights – Light on when corresponding zone
damper is closed.
E. Reversing Valve Selection Jumper – Configures Digitract 4 to
energize reversing valve in cool mode or heat mode. Place on O and
center pin to energize reversing valve in cool mode. Place on B and
center pin to energize in heat mode.
F. Microcontroller – Responsible for activation and control of the
unit and dampers based upon thermostat input.
G. Power Switch – When OFF, power from the heat pump transformer
is disconnected from the Digitract 4 and thermostats. When ON, power
from the heat pump transformer is supplied to the Digitract 4 and
the zone thermostats.
H. Heat Pump Status LEDs – Indicates what the DTHP4A is
energizing on the heat pump.
O/B: Reversing valve, yellow. On when the reversing valve is
energized.
Y1: Compressor, yellow. On when the first stage compressor is
energized.
Y2: Compressor, yellow. On when the second stage compressor is
energized.
G:Blower, green. On when the indoor blower is energized.
W2: Auxiliary heat, red. On when the auxiliary heat is energized.
PWR: Power, orange. On when power at R and C and the Power
Switch is on. Flashing when in Capacity Control cut out mode.
See Status Lights section, page 9, for further information.
I. FF fossil fuel jumper – Place jumper in FF position to use fossil
fuel features.
J. Adjustable potentiometer for balance point (BP), LO limit, HI limit
and changeover time.
SYSTEM CONTROLLER – HEAT PUMP DTHP4A
COMPONENTS
A. Heat Pump Unit/LAT Terminals – Connects to Heat Pump and
Leaving Air Sensor (LAT).
± LAT terminals. The LAT monitors the heat pump coil
10
The HVAC system is sized to handle the load of the entire home
or building. Because of this, when all the zones are not calling, the load
to the HVAC system can diminish below its designed capacity. Left
unchecked, the HVAC unit could freeze up or overheat. To compensate
for this, the Digitract 4 is furnished with a built in Capacity Controller.
The basic function of the Capacity Controller is to monitor the leaving air
temperature and cycle the unit off when the air is out of operating range
and, after a minimum four minute time delay, turn the unit back on when
the air temperature has returned within operating range. Additionally, for
heat pumps the Capacity Controller will turn on the heat pump auxiliary
heat if the coil leaving air temperature is not hot enough in heat mode.
Upon a heat call, the controller will energize W1 LED if the leaving air
temperature is less than High Limit Setpoint. This setpoint is determined by
adjusting the potentiometer located in the upper right corner of the controller,
HI. W1 will de-energize if LAT exceeds the HI setpoint, W1 LED will de-energize and the PWR LED will flash slowly indicating a stage 1 capacity cutout.
If the LAT is below the High limit, W1 will energize, W1 LED will illuminate.
W2 Heat operations – After W1 has operated continuously for 4 minutes
and LAT is less than High Limit minus 25°(if HI of 145° – 25°=120°),
then W2 will energize indicated by the W2 LED. If LAT rises to High
Limit minus 5°, then W2 will de-energize indicted by W2 LED off and
PWR LED flashing quickly. If all heat calls are satisfied both W1 and
W2 will de-energize and controller will go into a 4-minute purge
cycle.
Y1 Heat Operation – Upon a call for heat, the controller will energize
Y1 LED, if the LAT rises above the High Limit (potentiometer located on
controller top right corner, marked HI), then Y1 LED will de-energize
and PWR LED will flash indicating a stage 1 capacity cutout. After a
4-minute time delay the LAT will be checked; if LAT is less than HI
cutout, then Y1 LED will reenergize and PWR LED will stop flashing. If
the O/B jumper is in the B position, the O/B LED will illuminate with Y1.
Y2 Heat Operation – After 4 minutes of continuous Y1 operation, the
leaving air temperature will be checked. If the LAT is less than High
Limit (HI) minus 25° (HI of 120-25 = 95°), then Y2 will energize,
indicated by the Y2 LED. Y2 will cycle off when LAT is HI minus 5°
(120 – 5 = 115) or when all heat calls are satisfied.
Fossil Fuel Operation – For Fossil Fuel operation, FF jumper must be
placed in the FF position.
• For greater efficiency and comfort, an Outdoor Air Sensor, Part
# FOAS, should be used in the Fossil Fuel application. The FOAS is
used to lock out compressor operation when outside air temperature
has dropped below Balance Point setpoint, the temperature at which
that heat pump is no longer efficient. When the outside temperature
is less than Balance Point setpoint and there is a call for heat, Y1 and
Y2 will be locked out; and W2 will energize indicated by W2 LED
illuminating. The HI limit will be reset automatically to 135° to
provide HI limit protection for furnace. Calls for heat are recognized
from all thermostats; dampers for zones calling for heat will open,
indicated by DPR LEDs off, while zones not calling will close,
indicated by illuminated DPR LEDs. The Balance Point setpoint is
adjustable from 25° to 41° by moving Balance Point potentiometer to
desired setpoint. Refer to page 9 for potentiometer location on DTHP4A.
• Applications without FOAS will stage on time and temperature. With
the Fossil Fuel jumper in the FF position, after 8 minutes of continuous
heat operation, if leaving air is less than 90°, then W2 will energize.
Y1 and Y2 will de-energize indicated by LEDs off; W2 LED will
illuminate and furnace will start. The HI limit will be reset automatically
to 135° to protect furnace heat exchanger. DPR LED for calling zones
will be off, while DPR LEDs for non-calling zones will illuminate. All
thermostats are able to make calls for heat.
Auxiliary Heat (Electric Strip Heat) – After 8 minutes of continuous
operation the leaving air temperature is checked. If LAT is below 90°,
W2 will energize and W2 LED will illuminate. W2 will cycle off above
100°, or when all calls are satisfied.
Y1 Cool Operation – Upon a cool call, the controller will energize
Y1 and G. If the leaving air temperature drops below the low limit
setpoint, Y1 will be de-energized, the PWR led will flash indicating a stage
1 capacity cutout. After 4 minutes the leaving air temperature will be
checked again; if the leaving air temperature has risen above the cutout
set point, then Y1 will reenergize and PWR LED will stop flashing. If
controller is for a Heat Pump, and the reversing valve is in the O
position, the O/B output will be energized simultaneously with the Y1,
indicated by the O/B LED.
After 8 minutes of continuous Y1 run time, LAT (leaving air temperature)
will be checked. If LAT is greater than low limit (LO) plus 12° (LO of
45° + 12° = 57°), then Y2 will energize and Y2 LED will illuminate.
Y2 will cycle off when LAT drops below 5° plus low limit (45°+ 5° = 50°).
Y2 and G will de-energize when all calls are satisfied, and the controller
will go into a 4-minute purge cycle.
CAPACITY CONTROL AND STAGING
COOLING OPERATION – DTGE4A AND DTHP4A
HEAT OPERATION – GAS/ELECTRIC DTGE4A
HEAT OPERATION – HEAT PUMP DTHP4A
11
+
-
Y2
W1
G
W2
R
Y1
C
Red
Black
1.Drill a 3/8” hole in the supply air, ahead of the bypass tap.
A. GAS/Electric application – install sensor as far as possible from the FAU heat exchanger but still before
the bypass tap.
B. Heat Pump application – install the sensor after the indoor coil but before the electric strip heat
assembly.
2.Secure the sensor-mounting base to the duct or AHU cabinet (HP) with the self-tapping screws provided.
3.Run the shielded sensor cable back to the controller location; trim off any excess cable.
OAS INSTALLATION FOR FOSSIL FUEL
OAS, outdoor air sensor (Optional for Fossil Fuel applications), Sensor Installation
1. Install the OAS outside of the building, away from direct sun exposure, and above the snow line.
2. Run the sensor cable to the Digitract controller location; trim off any excess cable.
NOTE: Use of OAS with fossil fuel
creates a more efficient
system, providing greater
comfort control.
See page 11.
SHIELD
LAT AND OAS INSTALLATION
CAPACITY CONTROLLER – LAT INSTALLATION
Capacity control installation, LAT installation
4. The LAT requires no calibration.
3. The OAS does not require calibration.
4. Check the Balance Point (BP) POT on the controller. It is factory set at 33°.
Wiring Diagram for Fossil Fuel Applications
LAT
COIL
W1
Y1
Furnace
Shield
Red
Black
G
R
C
Shield
Red
Black
.
.
.
+
LAT
–
+
OAS
–
Y2
O/B
G
W2
Y1
R
E
.
C
DTHP4A
Controller
OAS (Outdoor Air Sensor)
Optional
R W Y1 O/B C
Outdoor Unit
12
Use the table below to determine which zone dampers to use.
Maximum Differential Pressure refers to the maximum static pressure drop in inches of water column between the
input (upstream) of the zone damper and the output (downstream) when the damper is closed.
There are two styles of round zone dampers, low pressure or medium
pressure. For systems 5 tons or under with a maximum differential static
pressure of 0.5”, use low pressure dampers. Otherwise use medium
pressure for up to 1.75” differential pressure on any system over 5 tons.
ROUND LOW PRESSURE ZONE DAMPERS (TR diam)
Zonex Systems round low pressure zone dampers can be used for systems up to 5 tons
with a maximum differential static pressure of 0.5”. These are two position, spring
open, power close dampers for very simple operation. Round damper sizes 9
inches and under are manufactured from 24 gauge galvanized steel. Sizes 10”, 12”,
14” and 16” are made from 20 - 22 gauge steel. All sizes are designed with rolled-in
stiffening beads for superior rigidity. The damper pipe is furnished with one crimped end
and one straight end for easy installation. A hat section supports a synchronous 24V
AC 60Hz 12VA motor and terminal board. The motor is designed for continuous full stall
operation. Special winding and heavy duty gearing provide for long motor life and
easy spring open operation. A cross pin on the motor shaft provides positive direct drive
to the damper blade shaft without a coupling or set screws, allowing for a quick and easy
motor change if required. Motor drive time from full open to full close is 30 seconds.
A red LED will be illuminated on the damper terminal board to indicate when the
damper is being powered closed. The LED will remain on when the damper is fully closed
and cycle off when the damper is opening or in the full opened position. Since this is a
spring open damper, in the event of power failure, the damper fails to the full open position.
ROUND MEDIUM PRESSURE ZONE DAMPERS
(101AMPD series)
The Zonex Systems round medium pressure zone dampers are recommended for any size
system above 5 ton, 2000 CFM, and are rated for a maximum of 1.75” SP. These dampers
are constructed from 20-22 gauge galvanized steel, with an elliptical damper disc. The
damper shell is manufactured with the supply end crimped and an air flow direction arrow.
The damper is driven by a 24-volt power open / power close, direct coupled actuator rated
at 2VA. The actuator assembly includes manual open and close stop adjustments and
mechanical drive release. The actuator is designed for full stall operation in the open and
close positions and requires no end switches.
MEDIUM PRESSURE (101AMPD diam)
LOW PRESSURE (TR diam)
ZONE DAMPERS
ROUND ZONE DAMPERS
SYSTEM SIZE
MAXIMUM
DIFFERENTIAL
PRESSURE
ROUND
DAMPER
RECTANGULAR
DAMPER
5 TONS OR UNDER
UNDER 7.5 TONS
7.5 TONS OF LARGER
0.5"
1"
1.75"
LOW PRESSURE
MEDIUM PRESSURE
MEDIUM PRESSURE
LOW PRESSURE
MEDIUM PRESSURE
HEAVY DUTY
13
ZONE DAMPERS
TYPICAL ROUND CAPACITIES*
* These air quantities were derived from a duct sizing chart .1” friction loss per 100’ of duct. All CFMs listed are approximate. For accurate selection
use duct sizing table or device.
Rectangular zone dampers are available for the DigiTract 4 controllers in three (3) styles:
TREC WxH for low pressure applications (5 tons or less) rated at .5” SP;
101MRTD WxH for medium pressure application up to 7.5 tons, rated at 1” SP;
101CD WxH for heavy duty applications over 7.5 tons, rated at 1.75” SP.
RECTANGULAR LOW PRESSURE ZONE DAMPERS
(TREC W x H)
Zonex Systems rectangular low pressure dampers can be used for systems up
to 5 tons with a maximum differential static pressure of 0.5”. These are two
position, spring open, power close dampers. They are constructed from heavy
duty galvanized steel. The damper is a single blade type that slips into a 2-1/2”
wide cutout in the existing duct and attaches with screws via a duct mounting
plate. The duct mounting plate is 5” wide. The drive assembly supports a
synchronous 24V AC 60Hz 12VA motor and terminal board. The motor is
designed for continuous full stall operation. Special winding and heavy duty
gearing provide for long motor life and easy spring open operation. A cross pin
on the motor shaft provides positive direct drive to the damper shaft without
a coupling or set screws. Motor drive time from full open to full close is 30
seconds. A red LED will be illuminated on the damper terminal board to
indicate when the damper is being powered closed. The LED will remain on
when the damper is fully closed and cycle off when the damper is opening or
in the full opened position. Since this is a spring open damper, in the event of
power failure the damper fails to the full open position.
RECTANGULAR MEDIUM PRESSURE ZONE DAMPERS (101MRTD W x H)
Zonex Systems rectangular medium pressure dampers are recommended for systems under 7.5 tons with a maximum differential static pressure of 1”.
These are power open, power close dampers. They are constructed from heavy duty aluminum and stainless steel. The damper is an opposed blade
type that slips into a 3-1/4” wide cutout in the existing duct and attaches with screws via a duct mounting plate. The duct mounting plate is 5” wide.
Power consumption is 6VA. The motors are designed for continuous full stall operation. Special winding and heavy duty gearing provide for long
motor life.
RECTANGULAR HEAVY DUTY ZONE DAMPERS
(101CD W x H)
Zonex Systems rectangular heavy duty dampers are recommended for systems
7.5 tons or larger with a maximum differential static pressure of 1.75”. These are
power open, power close dampers made of 20 gauge “snap-lock” steel frame
with S and Drive duct connections. Allow a 16” gap in the duct for the damper.
Formed steel blade stops incorporate a gasket for quiet operation and improved
structural rigidity. Rectangular dampers under 10” in height incorporate a
single blade design. Dampers 10” or over use opposed blade design. A full stall
motor, drawing 2 VA and a relay board control the damper position.
MEDIUM PRESSURE (101MRTD W x H) AND
HEAVY DUTY (101CD W x H) RECTANGULAR DAMPERS
LOW PRESSURE (TREC W x H) RECTANGULAR DAMPER
RECTANGULAR ZONE DAMPERS
15
ZONE DAMPERS
LOW AND MEDIUM PRESSURE RECTANGULAR DAMPER DIMENSIONS
HEAVY DUTY RECTANGULAR DAMPER DIMENSIONS
Motors on low and medium pressure dampers will be mounted on the Height (H) side. Bottom mount motors will be located on the Width (W)
side. *These air quantities were derived from a duct sizing chart .1” friction loss per 100’ of duct. All CFMs listed are approximate. For accurate selection
use duct sizing table or device.
Part Number 101CD W x H
Sizes available from 8” x 8” up to 48” x 48”
Part Number TREC W x H and 101MRTD W x H
Sizes available from 8” x 6” up to 24” x 20”.
RECTANGULAR DAMPER CAPACITIES*
Dampers listed below are standard sizes. For larger sizes and capacities, contact the factory.
2-1/2"
MOTOR
B
16
WIDTHHEIGHT
A
B16"
DEPTH
2-1/4"
W
5"
H
48" MAXIMUM WIDTH
4"
A
Rectangular heavy duty dampers should operate at 1500 FPM.
E.G. A 24" x 12" damper = 2 square feet.
2 square feet X 1500FPM = 3000 CFM.
8 1012 1416 18202224
200
6
280
8
390
10
490
12
14
HEIGHT IN INCHES
16
18
20
250
390
510
650
310
490
650
850
1000
1200
1400
WIDTH IN INCHES
390
590
800
1000
1250
1500
1750
16
440
680
950
1200
1500
1800
2100
500
770
1100
1400
1750
2100
2500
570
900
1220
1600
2000
2450
2850
630
960
1400
1850
2250
2300
3080
700
1090
1500
2000
2500
3000
3600
4000
The barometric bypass damper is for systems 5 tons or under. It utilizes
a weighted damper blade to maintain constant duct pressure. This
allows for easy installation without the need for electrical power or
wiring. The round barometric damper can be installed in any position.
The RBB rectangular damper must be installed with horizontal air
flow only.
SIZING: When only the smallest zone is calling, the maximum
amount of excess supply air will flow through the bypass damper. To
determine the proper size bypass damper to use, do the following steps:
Step 1: Calculate bypass air volume as follows.
A) Calculate total air volume at 400 CFM
per ton.
B) Calculate air volume of smallest zone in
CFM.
C) Calculate bypass air volume by subtract-
ing the smallest zone air volume from
the total.
(A - B = C)
Step 2: Select damper from sizing table.
Once you have calculated the bypass air volume from Step 1, use the
BAROMETRIC BYPASS SELECTION TABLE. From the table, select the
bypass damper with the CFM rating equal to or greater than the value
calculated in Step 1. For rectangular barometric dampers, use a
ductulator to convert from round to rectangular.
If bypassing more than 2000 CFM, use electronic bypass damper.
Example: You have a 4 ton system. Your smallest zone will use 500
CFM. The total CFM is 1600 CFM (400 * 4). Your bypass CFM is 1100
(1600 - 500). From the table, you determine that a 12” bypass damper
is needed.
Do not use the barometric bypass in any system over 5 tons.
For systems over 5 tons, or to bypass more than 2000 CFM, use the
electronic bypass.
RECTANGULAR & ROUND
BAROMETRIC BYPASS
BYPASS DAMPERS
BYPASS DAMPERS – BAROMETRIC
DiameterCFM
9”650
10”800
12”1200
14”1600
16”2000
ZONE DAMPERS
SIZING ZONE DAMPERS
If the ductwork already exists, simply size the damper to fit the ductwork.
For new systems or retrofit jobs:
a) Determine CFM from heat gain or loss calculations.
b) Select damper size by using a duct sizing table or calculator.
c) Select a Zonex Systems damper to fit the duct size selected for
that zone.
DAMPER INSTALLATION NOTES
1. Do not exceed 700 FPM in a register/diffuser branch duct.
2. If a damper is installed within 3 feet of register/diffuser, install sound
attenuating flex duct between damper and outlet.
3. Zone dampers should be preceded by 2’-4’ of straight pipe where
possible.
4. In attic installations and high humidity areas, the Zonex Systems
damper should be insulated along with the ductwork. The hat section
on the damper is delivered with insulation between the hat section
and pipe. Therefore, insulation should be applied to the round pipe
and be butted against the hat section, (do not insulate the motor terminal board or relay board). Both motor and the relay board generate enough heat so no condensation will develop on the hat section.
5. Remember to allow a 16” gap in the duct for Heavy Duty rectangular
CD dampers.
6. Low and medium pressure rectangular dampers slide into a 3” wide
cutout in the ductwork.
7. Install TR round dampers to the motor in the 9 to 3 o’clock position.
Do not install damper so the motor is in the 4 to 8 o’clock position.
BAROMETRIC BYPASS
SELECTION TABLE
Bypass dampers are used to provide constant air delivery through the air
handling unit. This is done by bypassing excess air from the supply duct
back to the return duct. As a zone is satisfied, its zone damper closes.
When this happens, the bypass damper opens just enough to bypass the
excess air. This will control static pressure and noise at the diffusers.
Zonex Systems offers two types of bypass dampers, Barometric and
Electronic. Each is available in round or rectangular configuration.
Barometric bypass dampers are limited to systems of 5 tons. Electronic
dampers can be used on any size system. For residential HVAC systems
with variable speed blowers, the barometric or electric bypass dampers
can be used. NOTE: When using the electric bypass (STBP/STCDBP), see
the Bypass Dampers - Electronic Section, Pages 19-22; or contact
Technical Support.
17
BAROMETRIC BYPASS
DAMPER
AIRFLOW
1
2
1. Damper Shaft
2. Lock Nut
3. Lever Arm
4. Counter Weight
3
4
INSTALLATION
The round barometric bypass damper can be installed in any position.
This damper is factory set for horizontal installation and can be field
modified for vertical installation. Do not run speed screws into damper
housing. Screws may interfere with damper travel. Make sure counter
weight is not obstructed in any way.
a)Install the bypass damper between the supply and return
plenums of the unit. It must be the first tap off the supply plenum.
b) Be sure the air flows through the damper in the proper direction
as indicated by the arrow on the damper. Airflow is always
from supply to return plenum. Be certain the damper shaft
is horizontal.
c) Loosen counter weight with allen wrench.
d) Loosen lever arm from damper shaft and allow to hang straight
down.
e)Fully close damper by grabbing damper shaft on side attached
to lever arm and turning clockwise until it stops.
f)While holding the damper fully closed, rotate the lever arm a
little to the right (facing the damper) and then screw in to
tighten to the damper shaft. Then tighten lock nut.
g)Be sure the damper is being held closed by the counter weight.
Proceed to setup.
BAROMETRIC BYPASS SETUP
a)Turn off all thermostats.
b) Turn on Switching Center/Controller and set fan switch to “ON”
position. Allow fan to run for 5 minutes to equalize pressure.
Then make sure all dampers are open by checking for air flow
out of each damper.
c)By moving counter weight up or down the lever arm, adjust it
so that the damper just wants to start opening.
d) If the damper cannot be held closed with the counter weight
all the way to the bottom of the lever arm, then hold the
damper shaft, loosen the lever arm from the damper shaft, and
rotate the lever arm farther to the right and retighten. Repeat
Step C.
e)The barometric bypass damper is now calibrated.
BAROMETRIC BYPASS STARTUP TEST
a)Have at least half of the zones call for either heating or cooling.
b) Check to be sure the calling zone dampers are open, (air is
flowing).
c) Verify the bypass damper is open. Note, the damper may not
fully open.
d) If the open zones are not noisy, the bypass damper is set.
BYPASS DAMPERS – BAROMETRIC
AIRFLOW
SHEET METAL
PIPE
AIRFLOW
BAROMETRIC
BYPASS
HORIZONTAL APPLICATION
A/C UNIT
RETURN
VERTICAL APPLICATION
OR
FURNACE
BAROMETRIC
BYPASS
SUPPLY
PLENUM
A/C UNIT
OR
FURNACE
RETURN AIR GRILLE
RETURN
AIR
PLATFORM
SUPPLY
PLENUM
AIRFLOW
ROOFTOP INSTALLATION Down Discharge Application
SUPPLY
PLENUM
OPEN RETURN PLENUM BYPASS APPLICATION
To prevent bypass air from
flowing out the return grill,
use a short open ended
return air plenum to
connect the bypass
damper to the unit.
RETURN AIR
GRILLE
SHEET METAL
PIPE
BYPASS DAMPER
AIR CONDITIONING
UNIT
A/C UNIT
OR
FURNACE
BAROMETRIC
BYPASS
AIRFLOW
RETURN
PLENUM
SUPPLY
DUCT
ROOF LINE
18
Diameter
CFM
8”
560
10”
900
12”
1250
14”
1700
16”
2200
18”
2600
PART #
SIZE D L
W
STBP08
8
8”
10”
11”
STBP10
10
10”
12”
13”
STBP12
12
12”
14”
15”
STBP14
14
14”
16”
17”
STBP16
16
16”
18”
19”
STBP18
18
18”
20”
21”
ROUND BYPASS SELECTION TABLE
RECTANGULAR BYPASS DAMPERS
SELECT FROM 8 x 8 thru 48 x 48
D
L
W
H
D
4”
W
48” MAXIMUM WIDTH
BYPASS DAMPERS – ELECTRONIC
ELECTRONIC BYPASS DAMPERS
Bypass dampers are used to provide constant air delivery through the air handling unit. This is done by bypassing excess air
from the supply duct back to the return duct. As a zone is satisfied, its zone damper closes. When this happens, the bypass
damper opens just enough to bypass the excess air. This will control static pressure and noise at the diffusers.
The Electronic Bypass Damper is used on any size system over 5 tons. The damper can be round (STBP) or rectangular
(STCDBP) with integrated static pressure control; and multiple dampers can be slaved together.
SIZING ELECTRONIC BYPASS DAMPERS
The bypass damper is to be sized for the total system CFM
@ 1500 FPM. System CFM should be calculated at 400
CFM per ton.
Example: A 5-ton system is rated at 2000 CFM (5x400 =
2000). When calculated at 1500 FPM, the bypass damper
should be 16”. Never undersize the bypass damper.
ROUND BYPASS DAMPER SELECTION
The Zonex Systems STBP damper is used for round
bypass applications. When you know the bypass CFM
requirements, use the ROUND BYPASS SELECTION
TABLE to confirm the round damper size.
NOTE: Multiple round dampers can be slaved from one
static pressure control to provide the correct capacity. One
large rectangular bypass damper may be used instead of
multiple round dampers. See below.
RECTANGULAR BYPASS DAMPER SELECTION
The Zonex Systems STCDBP WxH damper is used for
rectangular bypass applications. These dampers are also
sized for the total system CFM rated at 1500 FPM.
Multiple dampers can be slaved from a single static
pressure control.
19
Bypass air in CFM. Calculated at 1500 FPM.
Formula used: B = W X H / 144 X 1500, where B = Bypass air in CFM, W = damper width in inches, H= damper height in inches, 144 = 144
sq. inches per sq. ft., 1500 = 1500 FPM.
SLAVING BYPASS DAMPERS
Use only one Pressure Sensor when slaving two or more Bypass Dampers together. Connect the Pressure Sensor to one damper as described above.
Connect the slave dampers in parallel as shown. Up to 4 dampers can be slaved to one Sensor. The slaved dampers will self synchronize each time
the dampers reach full open or full close.
24283236404448
82000233326673000333336674000
102500291733333750416745835000
123000350040004500500055006000
143500408346675250583364177000
164000466753336000666773338000
184500525060006750750082509000
20500058336667750083339167 10000
22550064177333825091671008311000
246000700080009000100001100012000
2870008167933310500116671283314000
32800093331066712000133331466716000
369000105001200013500150001650018000
4010000116671333315000166671833320000
4411000128331466716500183332016722000
4812000140001600018000200002200024000
810121416182022
8667833 1000 1167 1333 150016671833
10833 1042 1250 1458 1667 187520832292
121000 1250 1500 1750 2000 225025002750
141167 1458 1750 2042 2333 262529173208
161333 1667 2000 2333 2667 300033333667
181500 1875 2250 2625 3000 337537504125
201667 2083 2500 2917 3333 375041674583
221833 2292 2750 3208 3667 412545835042
242000 2500 3000 3500 4000 450050005500
282333 2917 3500 4083 4667 525058336417
322667 3333 4000 4667 5333 600066677333
363000 3750 4500 5250 6000 675075008250
403333 4167 5000 5833 6667 750083339167
443667 4583 5500 6417 7333 82509167 10083
484000 5000 6000 7000 8000 9000 1000011000
WIDTH IN INCHES
HEIGHT IN INCHES
BYPASS DAMPERS – ELECTRONIC
RECTANGULAR BYPASS SELECTION TABLE
DAMPER
ACTUATOR
To Static Pressure Controller As Shown On The Bypass Wiring Diagram On Page 22.
**
RC RO MC
***
*
20
SLAVE
DAMPER
ACTUATOR
RC RO MC
TO NEXT SLAVE
BYPASS DAMPER
IF APPLICABLE
RC
RO
MC
BYPASS DAMPERS with INTEGRATED PRESSURE CONTROL
Part # STBP or STCDBP
Bypass Damper with Integrated Pressure Control is used to control bypass operations. The bypass damper modulates
to maintain static pressure as zone dampers open and close. The bypass system reduces air noise from the supply
registers caused by excessive air velocity. If the system is configured for intermittent fan mode and the system satisfies,
there will be a 3-minute delay to allow for system purge, after which the bypass damper will open to 25%, preventing
noisy rush of air through supply registers when fan starts up on a call for heat or cool. If the system is configured for
fan continuous operation, the STBP (Round) or STCDBP (Rectangular) Electronic Bypass will monitor static pressure
continuously, providing constant control of system static.
INTEGRATED PRESSURE CONTROL
DESCRIPTION
A. Supply air tube
B. 24vac R and C
C. Damper Terminal RO, RC, MC
D. LED lights
E. Adjustable Potentiometer
F. TP1 Test Point
Fig. 1
BYPASS DAMPER INSTALLATION
1. Verify the bypass damper is sized properly to the
system and not undersized. (Bypass damper
sizing is recommended for 100% of system
CFM.)
2. Bypass damper and controller are powered by a
dedicated 24vac 40VA transformer.
3. Do not install the bypass damper outside.
4. Locate the Integrated Pressure Control (IPC)
and air tube on the bypass damper.
5. Drill ¼”hole into the side of the supply duct 2’
after the bypass and before the 1st supply takeoff. Mount pressure supporting block over ¼”
hole, align hole in block with hole in duct. Use
provided sheet metal screws.
6. Install air tube into supply air duct by slipping
supplied plastic tubing into holes in support
block and duct. Slip tube 3” into the duct.
Pickup tubing fits snugly into provided hole.
7. Connect pressure tube from static air pickup to
Integrated Pressure Control.
Fig. 2
21
BYPASS DAMPER WITH INTEGRATED
BYPBYPASS DAMPERS with INTEGRATED PRESSURE CONTROLASS DAMPERS with INTEGRATED PRESSURE CONTROL
BYPASS CONTROL SETUP
1. Run all supply dampers to the full open position and
have blower motor running at 100% fan speed. (See
Note #1)
2. Manually close the bypass damper by pressing in the
release lever on the motor side of the actuator. With
the release lever pressed, rotate the damper actuator
collar to close the damper and release the lever to lock
the damper closed.
3. Quick Set Option: Turn the potentiometer on the
damper control board to the full left position and slowly
rotate RIGHT, until the “RC” RED LED turns on.
Now rotate LEFT just slightly, until RC LED turns off.
The IPC is ready for operation.
“RC” RED LED means damper closing.
“RO” GREEN LED means damper opening.
4. Static Pressure Option: The Integrated Pressure
Control Board can be field configured for specified
static pressure using a multi meter and the static
pressure – voltage chart. (Exhibit A). This chart shows
voltage (DC) to inches of W.C. (static pressure)
relationship. Use a multi meter set on VDC and place
the leads on the “C” terminal and “TP1” (test point
one) next to the potentiometer. The Voltage reading
translates to inches of W.C.
BYPASS CHECKOUT FOR STATIC
PRESSURE CONTROLLER
1. Make cool call at the zone thermostat of the smallest
zone.
2. Verify all zone dampers are closed except for calling
zone.
3. Verify noise at zone registers is not excessive. Adjust
the Integrated Pressure Control LEFT to lower noise
(airflow) or RIGHT to increase airflow until too
noisy.
BYPASS DAMPER WIRING DIAGRAM
WITH INTEGRATED BYPASS CONTROL
Note # 1: To open all dampers, it may be necessary to
remove Y outputs to unit on the zone control board and to
make full cool calls on all thermostats. This will modulate
dampers fully open and lock out compressor.
22
DAMPER TRANSFORMER
The 24V transformer connected to TR1 and TR2 of the Digitract 4
System Controller powers the zone dampers. The power rating of the
transformer must be sufficient to power the number of dampers used.
Also, a properly rated in line fuse must be used on the secondary of
the transformer. To determine the power rating of the transformer and
the amperage rating of the fuse, use the table below. If using a
combination of spring open and power open dampers, size as if all
dampers are spring open.
Note: The System Controller and thermostats are powered by the
HVAC unit transformer via terminals R and C.
STARTUP TEST, GAS/ELECTRIC DTGE4A
1. If there is no heating system, go to step 12
2. At System Controller:
a. Turn power switch to ON. Verify power LED is illuminated.
3. Turn off all thermostats except thermostat 1.
4. At zone 1 thermostat:
a. Set power switch to ON, if applicable.
b. Set to Heat mode.
c. Set fan switch to AUTO mode.
d. Set heat setpoint 4° above room temperature.
5. At System Controller:
a. Verify W1 and PWR LEDs are ON. If not, cycle System Controller
power switch OFF and then ON and recheck.
b. If fan jumper is across middle and top pin, verify that G is
energized for fan operation in Heat mode.
c. Verify that DPR 1 LED is OFF and DPR 2 through DPR 4 are ON.
6. At furnace, verify that furnace is on and blower fan is running. If the
G LED on System Controller is not on, the blower fan is controlled
by the furnace and there will be a delay before it turns on.
7. At zone 1, verify that air is coming out of register.
verify that W2 LED energizes and, if 2nd stage heat is available, 2nd
stage starts.
9. At next zone:
a. Verify that no air is coming out of register.
b. At thermostat:
1. Set power switch to ON, if applicable.
2. Set to Heat mode.
3. Set fan switch to AUTO mode
4. Set heat setpoint 4° above room temperature.
c. Verify that air is now coming out of register.
10. At previous zone, turn off thermostat, and verify there is no airflow.
Verify that DPR 2 is OFF and DPR 1, 3 and 4 are ON.
11. Repeat steps 9 and 10 for remaining zones.
12. Turn off all thermostats except zone 1.
13. At zone 1 thermostat:
a. Set power to ON, if applicable.
b. Set to Cool mode.
c. Set fan switch to AUTO mode.
d. Set cool setpoint 4° below room temperature.
14. At System Controller:
a. Verify Y1, G and PWR LEDs are on. If not, cycle System Controller
power switch OFF and ON and recheck.
b. Verify that DPR 1 LED is OFF and DPR 2 through 4 are ON.
15. At HVAC unit, verify air conditioner and blower are running.
16. Verify that air is coming out of registers.
NUMBER TR SERIES TR SERIES TR SERIES TR SERIESMED. PRESSURE/HEAVY DUTYMED. PRESSURE/HEAVY DUTYMED. PRESSURE/HEAVY DUTYMED. PRESSURE/HEAVY DUTY
8. After 4 minutes of W1 run time, check LAT. If LAT is less that
HI limit minus 25°, then W2 will energize. If LAT is greater than
HI limit minus 25°, remove LAT from supply plenum and
17. After 8 minutes, check LAT. If LAT is above LO cutout plus
23
23
12°, verify that Y2 energizes. If LAT is less than LO cutout plus
12°, remove LAT from supply plenum and verify Y2 operation.
STARTUP TEST, GAS/ELECTRIC DTGE4A (Continued)
18. At next thermostat:
a. Verify that air is not coming out of register.
b. At thermostat:
1. Set power switch to ON, if applicable
2. Set to Cool mode.
3. Set fan to AUTO mode.
4. Set cool setpoint 4° below room temperature.
c. Verify that there is airflow from register.
19. At previous zone, turn off thermostat and verify that there is no
airflow from register.
20. Repeat steps 18 and 19 for remaining zones.
Test complete.
1. Disconnect Y1, Y2, O/B, W2 and G wires between controller and air
handler. This will allow controller to cycle all stages of heat and cool
without energizing compressors, fans or heat strips.
2. Turn off all thermostats except zone 1.
3. At zone 1 thermostat:
a. Set power switch to ON, if applicable.
b. Set to Heat mode.
c. Set fan to AUTO mode.
d. Set heat setpoint 4° above room temperature.
4. At System Controller:
a. Verify Y1, G and PWR LEDs are ON. If not, cycle System Controller
power switch OFF and then ON and recheck.
b. If jumper O/B is on B, verify O/B LED is ON. Otherwise, verify O/B
LED is OFF.
c. Verify DPR 1 LED is OFF, and DPR 2 through DPR 4 LEDs are ON.
5. At next zone thermostat:
a. Set power switch to ON, if applicable.
b. Set to Heat mode.
c. Set fan switch to AUTO mode.
d. Set Heat setpoint 4° above room temperature.
6. Repeat steps 4 and 5 for all remaining zones. As a zone calls for
heat, the corresponding DPR LED for that zone will de-energize and
the damper will open. As each zone is satisfied, the associated DPR
LED will illuminate and the damper will close.
7. Verify a call for 2nd stage heat. Confirm that Y2 energizes after the
(leaving air temperature) is less than Y2 cut-in temperature (LO
cutout setpoint minus 25°; if HI limit is 120°, subtract 25° and
cut-in will be 95°). After a total of 8 minutes of continuous call for
heat, verify that W2 LED has illuminated, calling for electric strip
then W2 will energize and auxiliary heat is on.
8. Turn off all thermostats except zone 1.
9. At zone 1 thermostat:
a. Verify power switch is ON, if applicable.
b. Set to Cool mode.
c. Set fan to AUTO mode.
d. Set cool setpoint 4° below room temperature.
10. At System Controller:
a. Verify Y1, G and Power LEDs are on. If not, cycle System Controller
power switch OFF and ON and recheck.
b. If jumper O/B is in the O position, verify that O/B LED is ON. If
O/B is in the B position, verify O/B LED is OFF.
c. Verify DPR 1 LED is OFF and DPR LEDs 2 through 4 are ON.
11. At zone 2 thermostat:
a. Set power switch to ON, if applicable.
b. Set to Cool mode.
c. Set fan switch to ON.
d. Set cool setpoint 4° below room temperature.
12. Verify Y1, G and Power LEDs are ON. O/B LED is ON for O mode or
OFF for B mode. Verify damper LEDs for DPR 1 and 2 are OFF, and
damper LEDs for 3 and 4 are ON.
13. Turn zone 1 thermostat OFF. Verify damper 1, 3 and 4 LEDs are ON.
Damper 2 LED is OFF.
14. Repeat steps 11 through 13 at zone thermostats. Verify damper LEDs
for 3 and 4 are OFF when calls from zones are made.
15. Verify call for 2nd stage cool. Confirm that after the heat pump has
been running in Y1 for 8 minutes that Y2 will then energize. As the
temp will be at ambient temperature, allowing the controller to stage
up. With the heat pump outputs connected, after 8 minutes of
continuous running, the Leaving Air Temperature must be a minimum
of 12° above the LO cutout setting for Y2 to energize.
16. Turn off all thermostats.
17. Connect wires to System Controller terminals Y1, Y2, W2 and G.
18. Place call on zone 1 for Heat. Verify heat pump startup and airflow
on zone 1 registers.
19. Place a call on zone 2 for Heat, and verify airflow. Switch off zone
thermostat 1, and verify airflow.
20. Repeat for zones 3 and 4.
21. Turn off all thermostats.
22. Place a call on zone 1 for Cool. Verify cool startup and airflow on
zone 1 registers.
23. Place a call on zone 2 for Cool, and verify airflow. Switch zone
thermostat 1 to OFF, and verify airflow.
24. Repeat for zones 3 and 4.
Test complete.
STARTUP TEST, HEAT PUMP DTHP4A
heat pump has been running for 4 minutes. Y2 will energize if LAT
heat. After 8 minutes of continuous heat call, if LAT is less than 90°,
21. Reinstall LAT sensor, if removed for startup.
heat pump outputs have been disconnected for this test, the LAT
24
Digitract 4 TROUBLESHOOTING / SERVICE CHECKS
MalfunctionProbable CauseCorrective Action
Will not initiate cooling cycleController in heat modeDelay prior to changeover
Controller in changeover from heat mode4-minute purge cycle must complete
Thermostat has cooling anticipator (compensator)Remove anticipator
Air flow too low over evaporatorIsolate and correct air flow problem
Bypass damper opening prematurelyAdjust bypass damper closed w/ all zone dampers open
Will not initiate heat callsController in cool modeDelay prior to changeover
Controller in changeover from cool mode3-minute purge cycle must terminate
Heating anticipator incorrectly setSet anticipator to lowest setting
Bypass damper opening prematurelyAdjust bypass damper closed w/ all zone dampers open
Zone dampers will not closeLoss of 24V ac on TR1 And TR2Repair power source
Transformer VA too lowReplace w/ correct transformer
Dampers incorrectly wiredCorrect damper wiring
No output on damper terminal(s)Cycle power to controller. Verify thermostat inputs are correct.
If problem persists, replace controller
Zone damper remains closedZone not calling while mode is activeInitiate thermostat call
Triac shorted (Continuous 24V ac @ damper terminals) Replace controller
W2 will not energizeDischarge air temperature above 88° F. Normal operation
(DTHP4A only)Relay contact failure (W2 LED on)Replace controller
Bypass damper opening prematurelyAdjust bypass damper closed w/ all zone dampers open
Controller in cool modeVerify jumper JU1 position
Blower runs continuallyFan operation selected on any thermostatVerify fan switch on all thermostats
Fan relay contacts in controller seizedReplace controller, check 24 V AC
All thermostats will not callLoss of 24V ac on R and CRepair power source
Cooling calls short cycleLAT shorted (0V dc on + and – w/ LAT installed) Replace LAT
Heating calls short cycleLAT open (5V dc on + and – w/ LAT installed) Replace LAT
LAT wiring shorted (0V dc on + and – w/ LAT installed) Repair LAT wiring
Controller failure (0V dc on + and – w/ LAT removed)Replace controller
LAT electrical interference (Applicable to spark ignition) Install shielded cable to LAT, terminate shield on C terminal ONLY
LAT wiring open (5V dc on + and – w/ LAT installed) Repair LAT wiring
LAT SENSOR TEMPERATURE TO DC VOLTS / RESISTANCE CHART
The sensor DC voltage is read by placing the Black meter probe on any " ""C" terminal and the Red meter probe on the negative ( - ) sensor terminal.
PATENTED PRODUCT
Zonex Systems reserves the right to discontinue, or change at any time,
specifications or designs without notice and without incurring obligations.
Part #DT4MAN
Zoning
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www.zonexproducts.com
Copyright 2013 by Zonex Systems
Rev. October 2013
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