Auto-Zone Control Systems Auto-Zone CV-C Controller Installation Guide (Version 01A) - Manual (Page 16)

Section 2 Auto-Zone CV-C
2-6 Sequence of Operation
Pushbutton Override Pushbutton Override Pushbutton Override Pushbutton Override
Operation
Operation Operation Operation
This function requires a Space Temperature Sensor that also includes a Push-Button.
During unoccupied hours, the user can force the controller back to occupied operation by
pressing the override button for a period of time between 200 milliseconds and 3 seconds.
This overrides the schedule back to the occupied mode for a user defined period of time.
During Override operations, the user can cancel the override by pressing the override
button for a period of time between 3 seconds and 10 seconds. This removes the override
from the schedule and allows the controller to return to normal unoccupied operations.
If the override button is held for more than 10 seconds, it causes a space sensor failure
alarm. This is due to the fact that the override button actually shorts the space
temperature sensor input to ground. If this input is shorted to ground or left "floating"
with no sensor detected for more than 10 seconds, it is considered a failure.
HVAC Mode of Operation HVAC Mode of Operation HVAC Mode of Operation HVAC Mode of Operation
There are five possible modes of operation. These are Cooling Mode, Heating Mode,
Vent Mode, Fan Only Mode and the Off Mode. The HVAC mode of operation is
calculated the same way in both occupied and unoccupied modes of operation.
Off Mode The schedule is off and no overrides are active. There is no heating or
cooling demand in the space. Under these conditions, all outputs will be
off and the analog output will be set to 0.0 vdc.
Vent Mode No heating or cooling demand exists during the occupied mode of
operation. The fan will be on if the CVC is programmed for Constant Fan
operation.
Cool Mode A cooling demand is generated when the space temperature rises half the
amount of the Deadband Setpoint above the currently active Cooling
Setpoint. The space is considered satisfied when it drops that amount
below the Cooling Setpoint.