AAON MODGAS-XWR2 - MODGAS-XWR2 Overview; General Information and Features

5
MODGAS-XWR2 Technical Guide
OVERVIEW
General Information
Overview
The MODGAS-XWR2 Module (previously referred to as the
MODGAS-XWR-1) is designed to be used with White-Rogers
®
valves only. It will modulate up to two White-Rogers
®
gas
valves to maintain a desired Supply Air Temperature (up to
four modulating gas valves may be controlled when a second
MODGAS-XWR2 is configured as a slave module). The
MODGAS-XWR2 also controls the speed of the induction motors
in combustion air blowers. See Figure 1, page 6.
NOTE: The MODGAS-XWR2 provides two more relays
than the MODGAS-XWR and can replace the
MODGAS-XWR. See page 42 for replacement
instructions.
The MODGAS-XWR2 can be used in Stand-Alone Mode
or connected to a VCCX2 Controller, VCB-X Controller, or
VCM-X E-BUS (I
2
C) Controller using a modular or E-BUS
cable, depending on the type of controller used.
The MODGAS-XWR2 can have the following congurations:
• One modulating valve with one ignitor as one stage.
• Two modulating valves with one ignitor as one stage.
• Two modulating valves with two ignitors as one stage.
• Two modulating valves, with two ignitors as two stages.
Two MODGAS-XWR2 Modules (Primary/Secondary) may be
congured to control four modulating valves as one stage - two
valves with one ignitor on each board. In addition, two modules
may be congured to control four modulating valves with two
ignitors on each board. The rst valve on each board is stage one
and the second valve on each board is stage two.
NOTE: Primary/Secondary conguration is not supported
using I
2
C communications (VCM-X E-BUS).
The MODGAS-XWR2 can also control or eect control of
additional xed valves for additional stages of heat by using the
additional heat relays on the board itself. When the MODGAS-
XWR2 is attached to one of the listed AAON unit controllers,
these additional stages are aected through the AAON unit
controller. In Stand-Alone Mode, these additional xed heat
stages can be increased by attaching a 12 Relay E-BUS Expansion
Module. In Communications Mode, additional xed heat stages
can be increased by attaching a 12 Relay E-BUS Expansion
Module to the AAON unit controller.
Features
The MODGAS-XWR2 provides the following:
• Can control two gas valves using input from Proof of
Ignition Modules.
• A second MODGAS-XWR2 can be added to allow
control of four modulating gas valves.
• Monitors Supply Air Temperature and Supply Air Reset
and modulates gas valves to maintain the Supply Air
Temperature and Supply Air Reset Setpoints.
• Provides active relays to control the Fan, Fan Speed,
and Heat Stages.
• Controls up to four stages of Heat with one module.
• Contains a 2 x 8 LCD character display and four buttons
that allow for status display, setpoint changes, and
conguration changes.
NOTE: The MODGAS-XWR2 contains no user
serviceable parts. Contact qualified technical
personnel if your MODGAS-XWR2 is not
operating correctly.