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MODGAS-XWR2-B Technical Guide
SEQUENCE OF OPERATION
Operating Modes and Min Mode
Operation Modes
The MODGAS-XWR2-B can be used in Stand-Alone Mode or
connected to a AAON unit controller using an E-BUS or modular
cable.
Stand-Alone Mode
When used in Stand-Alone Mode (not connected to a AAON unit
controller), the MODGAS-XWR2-B will modulate the gas valve(s)
to maintain the Supply Air Temperature Setpoint configured on the
MODGAS-XWR2-B. The MODGAS-XWR2-B is activated by a
24 VAC signal to the HEAT EN input.
The following setpoints are adjustable on the LCD display in Stand-
Alone Mode:
• Supply Air Temperature Setpoint
• Supply Air Reset Temperature Setpoint
Communications Mode
When the MODGAS-XWR2-B is being used with an AAON unit
controller, information will be transferred between them via a
modular or E-BUS cable, depending on the type of unit controller
used.
In this configuration, the MODGAS-XWR2-B uses the Supply Air
Temperature from the AAON unit controller for control. The Supply
Air Temperature Setpoint and Supply Air Temperature Reset values
are set by the AAON unit controller.
If communication is interrupted between the MODGAS-XWR2-B
and the AAON unit controller, both boards will indicate an alarm.
The alarm condition will be cleared once communication is restored.
Min Mode
Min Mode is used to help eliminate overshoot of the Supply Air
Temperature Setpoint as additional stages of heat are activated.
When Min Mode is active, the modulating valves are commanded
to Min Position until the interval timer has expired. To disable Min
Mode, set the Min Mode deadband to zero.
The Min Mode works in the following order:
1.
The Min Mode will attempt to initialize after the first
stage of heat and any subsequent stage of heat.
2. If the Supply Air Temperature is below the Supply
Air Temperature Setpoint and within the Min Mode
deadband, Min Mode will run for a user defined interval.
3.
After the interval, the valve will modulate normally to
maintain the Supply Air Setpoint.
Содержание MODGAS-XWR2-B
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