AAON VCCX2 User Manual

49VCCX2 Controller Technical Guide
SEQUENCE OF OPERATIONS
Alarms
Direct Fire Alarms
In the Prism 2 Alarm Menu, click OK on the Direct Fire Alarms to
display the applicable alarms.
Figure 16: Prism 2 Direct Fire Alarms Screen
Failure Mode Alarms
High and Low Supply Air Temperature Alarm(s)
If the supply air temperature rises above the user-adjustable
High Supply Air Temperature Cuto Setpoint, heating will be
immediately deactivated, and a high supply air temperature cuto
alarm will be generated. The fan will continue to run. This mode
and alarm will be canceled if the supply air temperature falls below
the High Supply Air Temperature Cuto Setpoint by 5ºF.
If the supply air temperature falls below the user-adjustable Low
Supply Air Temperature Cuto Setpoint, all mechanical Cooling
will be immediately deactivated. If, after 10 minutes, the supply
air temperature is still below this setpoint, the fan and mechanical
heating will be deactivated, the outdoor air damper will close, and
a low supply air temperature cuto alarm will be generated. This
mode and alarm will be canceled if the supply air temperature rises
above the Low Supply Air Temperature Cuto Setpoint by 5ºF.
High and Low Control Temp Failure
When the space temperature rises above the Cooling Mode Enable
Setpoint plus the Control Mode High Alarm Oset Setpoint for 30
seconds, the controller will generate a high control temp failure
alarm. When the space temperature drops below the Heating Mode
Enable Setpoint minus the control Mode Low Alarm Oset Setpoint
for 30 seconds, the controller will generate a low control temp failure
alarm. Both oset setpoints are user-adjustable.
Preheater Alarm
This alarm indicates a leaving air temperature cuto alarm condition
which is activated if the controlling leaving air temperature has
dropped below 35ºF for more than two minutes. The alarm will be
disabled if after a xed delay period the leaving air temperature
has risen above 35ºF
Sump Drain
When the Outside Air Temperature drops below the Sump Drain
Enable Temperature, the Evaporative Condenser drain valve will
open.
Expansion Boards
If the controller is congured to have any of the below expansion
boards (Modules), but the VCCX2 controller does not detect that board,
then the applicable alarm will occur. If the board is properly
detected after the unit has alarmed, the alarm will be cleared.
• Compressor Modules #1-6
• Pre-Heater Module
• MHGRV-X Module
• Modgas-X Module
• EM1 Expansion Module
• 12 Relay Expansion Module
• Sub Cool Module #1
• Sub Cool Module #2
• Missing Evap Condenser Module
• Missing Fan Array Controller

AAON VCCX2 Specifications

General

Brand	AAON
Model	VCCX2
Category	Controller
Language	English