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
.
