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DIGI3U Man. 7-05 DIGI3U
Three-Zone, Universal Controller for
Gas/Electric or Heat Pump Applications
Installation Guide
Part #D3MAN
July 2008
Zoning Systems
Thats all we do.
3-Zone
Controller
for the RNC
Market 1
Fused 24V 40VA Transformer
D
IGI3U
System Controller
73
73
73
5
2
3
1
4
6
ZONE 3
ZONE 2
ZONE 1
LAT
DIGI3U is an economical auto-changeover 2 or 3 zone controller, perfect for residential RNC construction or smaller zoning systems. The DIGI3U
is a universal board that is field configurable for Gas/Electric or Heat Pump applications. The DIGI3U provides Emergency Heat control and an optional
LAT providing capacity control while protecting the coil from freezing or the heat exchanger from premature failure.
INTRODUCTION
SYSTEM DESCRIPTION
The DIGI3U is a 3-zone, auto-changeover zone controller, which can be
field configured for single stage Gas Electric or Heat Pump with auxiliary
heat applications. The DIGI3U is designed to be economically priced,
easy to install and yet full featured for the residential new construction
market. The controller offers integrated capacity control when the
optional LAT is connected, and any zone thermostat can make a
heat or cool call.
Gas Electric configuration use standard single stage Gas Electric
thermostats. The LAT leaving air sensor can be wired into the system to
provide high and low temperature limits for compressor and heat
exchanger protection. The controller is shipped configured for Gas
Electric operation and has a 1K ohm resistor installed in the S S (sensor)
terminals of the controller. The resistor is used in place of the LAT for
2-zone Gas Electric installations that do not have a bypass. When bypass
is used, the optional LAT leaving air sensor must be connected in place
of the resistor to enable the capacity control to function in the controller.
NOTE: 3-zone installations must have bypass.
Heat Pump configuration use a standard Heat Pump thermostat
(1 stage cool, 2 stage heat) for the STAT 1 position. Standard single stage
Gas Electric thermostats are used for STAT 2 and STAT 3 positions on the
controller. Emergency Heat operation is initiated from the Heat Pump
thermostat on STAT 1.
The LAT supply air sensor must be used when the DIGI3U controller is
configured for Heat Pump operation. The controller will then provide
high and low limit control to protect the compressor and also control
the auxiliary heat operation, based on the supply air temperature.
1
2
3
4
5
6
DIGI3U universal GE/HP controller
LAT capacity control
Zone Dampers
Thermostats compatible with most
thermostats
Barometric Bypass
Fused 24V 40VA transformer to power dampers
NOTE: Prior to June 1, 2005 the DIGI3U controllers with software versions V1.4 through V1.7 were designed to use only Gas Electric thermostats
when configured for Heat Pump operation. If you are replacing an older controller, utilized on a heat pump with this new version, simply
replace the existing Gas Electric thermostat on the STAT 1 position with a standard Heat Pump thermostat, and follow the wiring diagram on
page 4 in this Installation Guide. DIGI3U DESIGN INFORMATION
2
2-3 Zone Application with Bypass Damper and LAT Sensor Use
this method if your application is for 2 or 3 zones using a bypass damper
and LAT sensor. Zonex Systems recommends that all systems use a
bypass damper and LAT to maximize system efficiency and comfort.
Ductwork design should follow typical duct design procedures: use
ductulator to verify airflow requirements, and follow bypass-sizing
calculations found in bypass guidelines of this manual.
2-Zone Gas/Electric Applications without a Bypass Damper or
LAT Sensor
When designing a system without a bypass damper or
LAT, it is necessary to oversize the ductwork and supply registers in
order to reduce noise caused by excessive static in HVAC system. Duct
runs and dampers must be oversized by 70%, and supply grills must
be increased in size to move twice the volume of air at 700 FPM; e.g.,
if zone calls for 250 CFM and a 12x8 register were sized for non-zoned
application, double the volume of air to 500 CFM, and size register for
700 FPM, or a 14x8-supply register. If the Zonex Systems LAT capacity
control is not applied, a field supplied freeze protection and high limit
device must be installed to protect equipment. This should only be
applied to designs in which both zones are approximately the same size.
NOTE:
All Heat Pump installations require the LAT sensor.
1. Remove factory installed 1K ohm resistor on S S.
2. Gas/Electric applications install sensor as far as possible from
the FAU heat exchanger but still before the bypass tap.
3. Heat Pump application install the sensor after the indoor coil
but before the electric strip heat assembly.
4. Secure the sensor-mounting base to the duct or AHU cabinet (HP)
with the self-tapping screws provided.
5. Run wire from the LAT sensor to S S terminals on DIGI3U controller.
Insert one wire under each S terminal, and tighten terminal screw.
6. LAT does not require calibration.
DESIGN INSTRUCTIONS
THERMOSTAT INFORMATION
LAT CAPACITY CONTROL INSTALLATION INSTRUCTIONS
For Gas Electric applications use standard single stage Gas Electric, auto changeover thermostats.
For Heat Pump applications use a standard Heat Pump thermostat (1 stage cool / 2 stage heat) for STAT 1 position only. Use standard single stage Gas
Electric, auto changeover thermostats on STAT 2 and STAT 3 positions.
S S
DIGI3U System Controller 3
24V 40VA Transformer
to Power Dampers
W-O/B
O/B
G
Y
R
C
AIRFLOW
BYPASS
DAMPER
ZONE 3
THERMOSTAT
R Y W G C
ZONE 2
THERMOSTAT
R Y W G C
ZONE 1
THERMOSTAT
R Y W G C
1
1
2
2
3
3
TR1
TR2
R Y O/B W2 G C
R Y W G C
R Y W G C
R
Y
G
W-O/B
W2
C
O O O
LED
Y
O/B W
W2
G
DPR1
DPR2
DPR3
GE
HP
B
POWER
SWITCH
DIGI3U
A/C UNIT TERMINALS
DAMPER OUTPUTS
STAT 2
STAT 3
STAT 1
O
PWR
CONTROL CHIP
O
O
LED
S S
JP1 JP2
W
WIRING GAS/ELECTRIC DIGI3U
S S terminals for LAT capacity control. If not applied, leave 1k ohm resistor in place; and field supplied high
and low limits should be added.
Transformer damper transformer 24vac 40va 2 amp fuse
Damper Terminals
JP1 not used in Gas/Electric applications
JP2 configuration jumper for Gas/Electric or Heat Pump operation
Unit Terminals outputs to furnace and condenser
Thermostats standard single stage heat/cool thermostats
LAT Sensor location mount sensor in supply before bypass takeoff
1
1
2
3
4
5
6
7
2
3
4
5
6
7
Follow this diagram for Gas/Electric applications. S S terminals for LAT capacity control. Heat Pump application requires the LAT
Connect W2 from controller to electric heat terminal of air handler for units with electric heat. The LAT sensor must be
installed in the supply air stream, between the indoor coil and electric strip heat elements.
Thermostats Standard Heat Pump thermostat is required for STAT 1.
Gas/Electric thermostats are required for STAT 2 and STAT 3.
Zone Damper Terminals refer to Wiring Zone Dampers on page 5.
Transformer Damper Transformer 24vac 40va 2 amp fuse.
JP1 Place in O position for unit energizing reversing valve for cool; place in B position for unit energizing reversing valve
in heat.
JP2 Heat Pump or Gas/Electric jumper is used to configure controller. Factory set for Gas/Electric operation.
4
24V 40VA Transformer
to Power Dampers
W-O/B
O/B
G
W2
Y
R
C
AIRFLOW
BYPASS
DAMPER
1
1
2
2
3
3
TR1
TR2
R Y O/B W2 G C
R Y W G C
R Y W G C
R
Y
G
W-O/B
W2
C
O O O
LED
Y
O/B W
W2
G
DPR1
DPR2
DPR3
GE
HP
B
POWER
SWITCH
DIGI3U
A/C UNIT TERMINAL
DAMPER OUTPUTS
STAT 2
STAT 3
STAT 1
O
PWR
CONTROL CHIP
O
O
LED
S S
JP1 JP2
W
HEAT PUMP STAT
ZONE #1
GAS/ELECTRIC STAT
ZONE #3
R Y W G C
R Y W G C
R Y O/B W2 G C
GAS/ELECTRIC STAT
ZONE #2
E
WIRING HEAT PUMP DIGI3U
1
1
2
3
4
5
6
7
2
3
4
5
6
7
Follow this diagram for Heat Pump applications. 5
WIRING ZONE DAMPERS
Fused 24V 40VA Transformer.
Transformer and fuse must be sized for total number of
zone dampers (12va per damper).
TR
SERIES
DAMPER
M M
1
2
3
3
TR1
TR2
2
1
DIGI3U
SYSTEM
CONTROLLER
ONE TO THREE TR SERIES
DAMPERS
Fused 24V 40VA Transformer.
Transformer and 2 amp fuse.
TR
SERIES
DAMPER
M M
1
2
3
3
TR1
TR2
2
1
DIGI3U
SYSTEM
CONTROLLER
Wiring Up to Three TR Series Dampers to a Zone
Wiring One TR Series Damper to a Zone 6
SYSTE