Auto-Zone Control Systems Auto-Zone CV-C Controller Installation Guide (Version 01A) - Manual (Page 20)

Section 2 Auto-Zone CV-C
2-10 Sequence of Operation
DX Cooling Operation DX Cooling Operation DX Cooling Operation DX Cooling Operation
If the user has configured the CVC with the DX Cooling option, the following sequence
of operation occurs during a cooling demand.
Once a cooling demand exists (see HVAC Mode of Operation), the following conditions
must be met before any relays can be activated:
a. Make sure any stages of heating are staged off or the hot water valve is
closed.
b. Make sure the Changeover Delay is satisfied. This only applies if the
previous demand was for heating.
c. Check the Outdoor Air Temperature to verify the cooling is enabled to run
due to warm temperatures.
d. If the Economizer option was enabled, the Economizer must be 100%
open if the outside air has enabled it for operation.
e. Check the current Minimum Off Timer to make sure this stage has been
off long enough since the last time it was cycled on and back off.
f. If there is more than 1 stage, check the Staging Delay Time from the
previous stage to be sure it has elapsed before activating the second stage.
g. If we are activating stage #2 or higher, make sure the Space Temperature
Demand is large enough to require the additional stages to activate.
The formula for determining the amount of demand required for each
additional stage is shown below:
Level = ((Deadband / 2) + ((Deadband / 2) * ActiveStages ))
IF Temperature > (Setpoint + Level) THEN its OK to activate another
stage.
( Active Stages refers to the number of compressors currently running. )
Example: Deadband = 1°F
Setpoint = 74°F
Stage #1 Activates @ 74.5°F - Deactivates @ 73.5°F
Stage #2 Activates @ 75.0°F - Deactivates @ 74.0°F
Stage #3 Activates @ 75.5°F - Deactivates @ 74.5°F