Auto-Zone Control Systems Auto-Zone CV-C Controller Installation Guide (Version 01A) - Manual (Page 21)

Auto-Zone CV-C Section 2
Sequence of Operation 2-11
If you have configured the system to control De-Humidification with the DX Cooling
then the compressors are staged on at a rate equal to the Cool Staging Period if the
Humidity reading is above a user defined Humidity Setpoint. This control ignores the
Space Temperature which means it can cause a heating demand in the space. If this
occurs, the cooling remains on to de-humidify the air while the heat runs to warm up the
space. As the humidity drops below the Humidity Setpoint by the Humidity Deadband
value, the compressors can stage off if they have been on at least one minute. If there is
still a cooling demand in the space and the demand requires the currently active cooling
stages to be on, then no staging off will occur until the demand drops low enough to stage
the compressors off.
Ignoring the Humidity Control for the moment, the compressors will stage off if the
following conditions are true.
a. The space temperature has dropped enough to remove a demand for the
currently active stage. ( see previous screen for stage off levels )
b. The outside air has dropped enough to disable the compressors.
c. The Supply Air has dropped below 45°F or 7.2°C.
d. Someone has reduced the number of cooling stages to less than what are
currently active.
e. The compressor stage has been on at least one minute.
The staging of compressors always occurs based on both temperature demand and
specific intervals based on whether the unit is staging up or down. There are four timers
that need to be satisfied:
a. Staging Delay Timer ( User Adjustable )
If a large demand exists when the cooling mode is entered all available
stages would be called for. Only one stage at a time can actually be
activated. The Staging Delay period must be satisfied before each additional
stage is activated.
b. Minimum Run Timer ( Not Adjustable )
Once a stage has been activated, it must remain for at least one minute
before it is allowed to turn off again. This protects the equipment from short
cycling.