6
SYSTEM CONTROLLER OPERATIONS – DIGI3U
GAS/ELECTRIC OPERATION
Gas Electric Operation Cool with LAT:
Remove the factory installed
1K ohm resistor and install LAT sensor wired to SS terminals of DIGI3U
controller.
When any thermostat calls for cool, Y and G LEDs will illuminate, indi-
cating outputs to unit are energized and unit is running. Damper LEDs
for non-calling zones are illuminated, indicating that dampers are
closed. When all calls are satisfied, Y, G and damper LEDs will go off, de-
energizing unit and opening all dampers.
When the leaving air temperature drops below 45°, Y will de-energize
and G will remain on for 3 minutes. After 3 minutes, if the leaving air
temperature has risen above 45° cutout limit, Y will energize and
cooling will restart.
After all calls are satisfied, a 3-minute purge will be initiated by controller.
During this time the controller will not allow any calls for heat or cool.
Heat Operation with LAT:
When any thermostat places a call for
heat, the W LED will illuminate and output to furnace will be energized.
Damper LEDs for non-calling zones will illuminate, indicating that
dampers are powered closed.
If leaving air rises above 145°, W will de-energize and gas valve/electric
heat will shut off. After 3 minutes, if leaving air temperature is less than
145°, then W LED will illuminate and heat will restart. When all calls
for heat are satisfied, W and damper LEDs will go off, de-energizing out-
puts to furnace and dampers.
After all calls are satisfied, controller will initiate a 3-minute purge.
During this time controller will not allow any calls for heat or cool.
Cool Operation without LAT:
If not using the LAT capacity control, a
field supplied high and low limit device will need to be applied to sys-
tem to protect equipment.
When any thermostat places a call for cooling, the power LED will flash
and all dampers will remain open. After 3 minutes, Y and G LEDs will
illuminate and energize condensing unit and fan. Damper LEDs for non-
calling zones will illuminate, indicating that dampers are closed.
After initial call for cooling or low limit cutout, all cooling calls will
initiate a 3-minute fan purge cycle. When all calls are satisfied, Y, G
and damper LEDs will go off and controller will initiate a 3-minute
time delay. During this time delay, controller will not allow a call for heat
or cool.
Heat Operation without LAT:
When a call for Heat is sent to the
controller, a 3-minute time delay is initiated. This time delay is indicated
by a flashing power LED.
When the 3-minute time delay is complete, the power LED is illuminated
constant and the controller will then energize the Heat output including
the corresponding damper signals.
A field supplied high and low limit device is required to provide HVAC
system protection.
Configure the DIGI3U for GE operation.
Jumper JP2 must be placed in GE position on controller. This will allow controller to control gas fur-
naces and electric heat air handlers and cooling condensers.
FOR APPLICATIONS
WITHOUT
LAT CAPACITY CONTROLLER
FOR APPLICATIONS USING THE LAT SENSOR
