Auto-Zone Control Systems Auto-Zone Plus Systems Installation & Operation (Version 03A) - Manual (Page 174)

Section 4 Auto-Zone Plus
4-24 Start-Up and Troubleshooting
user requires the system to re-calibrate the Pressure Sensor, check the Auto-Zone Plus
manual for keypad operations to perform this calibration.
The bypass damper always drives to its OPEN position first and then to its CLOSED
position. If your damper appears to be operating in reverse you may need to select
Reverse Acting damper operation from the Configuration menu. (See Section 3)
2.1.3 Purge Mode
During the Purge Mode of operation all the Zone Dampers are driven to their 100% open
position. All heating and cooling is locked out, the Economizer is held closed ( If
Installed ) and only the Main Fan is running with Static Pressure Control in operation.
The Purge Mode was designed to clear the stagnant air out of the plenum and attempt to
equalize the zone temperatures as much as possible before actually using the results of the
Zone Polling to determine the heating or cooling needs in the system.
2.1.4 Return Air Control
If for some reason the Zone Manager loses communication will all of the Zone
Controllers connected on the loop, then the Zone Manager will go into Return Air
Control mode. The Heating and Cooling will then be controlled by the Return Air
Temperature Setpoints (adjustable) based on the Return Air Temperature Sensor readings
instead of the Zone Controller’s demands. It will stay in this mode until communications
are established between the Zone Manager and at least one Zone Controller.
2.1.5 Operating Summary
There is a standard set of operating instructions that are continuously performed over and
over during normal Zone Manager operations. They are listed below.
a. Update Time & Date on LC Display (Basic systems)
b. Read analog inputs for temperatures, pressures and binary contact closures
c. Poll all the configured zones and save all the temperatures and setpoints
d. Broadcast the operating commands and temperatures to the zones
e. Calculate Occupied/Unoccupied mode of operation
f. Calculate HVAC mode of operation
g. Set all outputs to match calculations for heating, cooling, or vent mode
h. Keep alarms and mode of operation updated on LC Display
i. Store data in internal trend log if ready for another log
j. Repeat steps a - i continuously