AAON MODGAS-XWR User Manual

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OPERATION MODES & STAGING CONFIGURATIONS
19
MODGAS-XWR2 Technical Guide
Operation Modes & Staging Congurations
Operation Modes
The MODGAS-XWR2 Controller can be used stand-alone or connected
to a Main Controller using a modular cable (communicating).
Stand Alone Mode
When used in a stand-alone application (not connected to a Main Control-
ler via a modular cable), the MODGAS-XWR2 Controller will modulate
the gas valve(s) to maintain the DISCHARGE setpoint congured on
the MODGAS-XWR2 Controller LCD display. The MODGAS-XWR2
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-XWR2 Controller:
• Supply Air Temperature Setpoint
• Supply Air Reset Temperature Setpoint
Communicating Mode
When the MODGAS-XWR2 Controller is connected to a Main Con-
troller via a modular cable, the necessary information will be passed
between the MODGAS-XWR2 and the Main Controller to properly
operate in the Heating Mode.
If the communication is interrupted between the MODGAS-XWR2
Controller and the Main Controller, both boards will show an alarm.
When communication is restored, the alarms will go away.
In this con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-XWR2 from the Main Controller.
MODGAS-XWR2 Staging Congurations
The MODGAS-XWR2 can be congured for various Staged Heat con-
gurations. These congurations can be used in conjunction with the
VCM-X E-BUS Controller, VCB-X Controller, VCCX2 Controller, or
12 Relay E-BUS Expansion Module.
MODGAS-XWR2 Stand-Alone Conguration
The rst and second conguration screens designate the Primary and
Secondary boards if using two MODGAS-XWR2’s.
The third conguration screen allows selection of Stand-Alone Auto
(no 12 Relay board) or Stand-Alone Forced (using the 12 Relay board).
The fourth conguration screen allows selection of the Total Stages,
which is the number of Heat Stages installed in the unit (note that if there
are two heat units to be operated in a primary/secondary arrangement,
this is considered 1 stage of heat).
The fth conguration screen selects the conguration. The options
for Stand-Alone operation are (1) 1 modulating, 1 ignitor, 1 stage, (2)
2 modulating, 2 ignitors, 1 stage, (3) 2 modulating, 2 ignitors, 2 stages
(which allows a secondary MODGAS-XWR2), and (4) 2 modulating, 1
ignitor, 1 stage (which allows a secondary MODGAS-XWR2).
MODGAS-XWR2 Stand-Alone with 12-Relay
E-BUS Expansion Module
In order for the MODGAS-XWR2 to communicate properly to the
12 Relay Expansion Module, “S/A MODE” needs to be congured
to “FORCED”. This conguration will make the MODGAS-XWR2
initiate communications with the 12 Relay Expansion Module through
the E-BUS cable.
MODGAS-XWR2 Communicating with AAON
Unit Controller
The rst and second conguration screens designate the Primary and
Secondary boards if using two MODGAS-XWR2’s.
The fourth conguration screen allows selection of the Total Stages,
which is the number of Heat Stages installed in the unit (note that if there
are two heat units to be operated in a primary/secondary arrangement,
this is considered 1 stage of heat).
If more stages of heat are needed besides the MODGAS-XWR2 and the
main control board’s congurable relays, a 12 Relay E-BUS Expansion
Module or an additional expansion board can be connected to the Main
Controller and heat stages can be congured for the 12 Relay board from
the Main Controller. If using the 12 Relay board, the third conguration
screen must be set at Stand-Alone Forced.
The fth conguration screen selects the conguration. The options
for Stand-Alone operation are (1) 1 modulating, 1 ignitor, 1 stage, (2)
2 modulating, 2 ignitors, 1 stage, (3) 2 modulating, 2 ignitors, 2 stages
(which allows a secondary MODGAS-XWR2), and (4) 2 modulating, 1
ignitor, 1 stage (which allows a secondary MODGAS-XWR2).
NOTE: The Primary/Secondary conguration is not supported
when using the VCM-X E-BUS Controller.
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-XWR2 and two stages are active on the main control
board, the current heat stage displayed will show HEAT STAGE 4.

AAON MODGAS-XWR Specifications

General

Brand	AAON
Model	MODGAS-XWR
Category	Controller
Language	English