Orion System MODGAS-XWR - Manual (Page 13)

OPERATION MODES & STAGING CONFIGURATIONS
13 MODGAS-XWR Technical Guide
Operation Modes & Staging Confi gurations
Operation Modes
The MODGAS-XWR Controller can be used stand-alone or connected
to a Main Controller using a modular cable.
Stand Alone Mode
When used in a stand-alone application (not connected to a Main Control-
ler via a modular cable), the MODGAS-XWR Controller will modulate
the gas valve(s) to maintain the DISCHARGE setpoint confi gured on
the MODGAS-XWR Controller LCD display. The MODGAS-XWR
Controller is activated by a 24VAC signal to the HEAT EN input.
The following describes the setpoints available in stand-alone mode for
adjustment using the LCD display on the MODGAS-XWR Controller:
• Supply Air Temperature Setpoint
• Supply Air Reset Temperature Setpoint
Communicating Mode
When the MODGAS-XWR Controller is connected to a Main Controller
via a modular cable, the necessary information will be passed between
the MODGAS-XWR and the Main Controller to properly operate in
the Heating Mode.
If the communication is interrupted between the MODGAS-XWR Con-
troller and the Main Controller, both boards will show an alarm. When
communication is restored, the alarms will go away.
In this confi guration, the Supply Air Temperature Setpoint is set using
the Main Controller and the Supply Air Temperature Reset (if used) is
calculated by the Main Controller. The Supply Air Temperature is sent
to the MODGAS-XWR from the Main Controller.
MODGAS-XWR Staging Confi gurations
The MODGAS-XWR can be confi gured for various Staged Heat con-
fi gurations. These confi gurations can be used in conjunction with the
VCM-X Controller, VCB-X Controller, or
12 Relay Expansion Module .
MODGAS-XWR Stand-Alone Confi guration
In the confi guration screens, select the total Stages as the number of Heat
Stages installed in the unit. This is the number of Fixed and Modulating
Stages combined. Next, select the total Modulating Stages installed in
the unit (White Rodgers valves).
The options for Stand-Alone operation without additional boards are
(1) One modulating, (2) Two modulating, and (3) One modulating and
one fi xed.
MODGAS-XWR Stand-Alone with 12-Relay
E-BUS Expansion Module
If the total number of heat stages exceeds two in a stand-alone opera-
tion, then a 12 Relay Expansion Module is needed for proper control.
In the confi guration screens, select the total stages as the number of heat
stages installed in the unit. This is the number of fi xed and modulating
stages combined. There can be up to 14 total stages in this confi gura-
tion. Next, select the total modulating stages installed in the unit (White
Rodgers valves).
The options for stand-alone with 12 relay expansion are (1) One modu-
lating with up to 13 fi xed stages and (2) Two modulating with up to 12
fi xed stages.
In order for the MODGAS-XWR to communicate properly to the 12
Relay Expansion Module, “S/A MODE” needs to be confi gured to
“FORCED”. This confi guration will make the MODGAS-XWR initi-
ate communications with the 12 Relay Expansion Module through the
E-BUS cable.
MODGAS-XWR Communicating with AAON
Unit Controller
If the unit is installed with a main control board, then it needs to be
connected to the MODGAS-XWR via an I
2 C or E-BUS Expansion
cable. In the confi guration screens, select the total onboard stages as
the number of heat stages connected to the MODGAS-XWR. This is
the number of fi xed and modulating stages combined. Next, select the
total onboard modulating stages installed in the unit (White Rodgers
valves). Additional fi xed stages of heat will be confi gured on the main
control board. Confi gure the fi rst stage of heat on the main control board
as the combined stages of heat connected to the MODGAS-XWR. If
more stages of heat are needed besides the MODGAS-XWR and the
main control board’s confi gurable relays, a 12 relay expansion or an
expansion board can be connected and heat stages can be confi gured
from the main control board.
The confi gurable options on the MODGAS-XWR for this setup are
(1) One modulating, (2) Two modulating, and (3) One modulating and
one fi xed.
The status screen displaying the stage status will show the current heat
stage of all heat stages on the unit. For example, if two stages are active
on the MODGAS-XWR and two stages are active on the main control
board, the current heat stage displayed with show HEAT STAGE 4.