Auto-Zone Control Systems Auto-Zone CV-C Controller Installation Guide (Version 01A) - Manual (Page 25)

Auto-Zone CV-C Section 2
Sequence of Operation 2-15
Step Heating Operation Step Heating Operation Step Heating Operation Step Heating Operation
If the user has configured the CVC with the Step Heating option, the following sequence
of operation occurs during a heating demand.
If the controller was configured for De-Humidification, then any statements concerning
the cooling being off before the heat can activate can be ignored as the cooling is used in
conjunction with the heat to reduce humidity and maintain space temperature.
Once a heating 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 cooling are staged off or the chilled water valve is
closed.
b. Make sure the Changeover Delay is satisfied. This only applies if the
previous demand was for cooling.
c. Check the Outdoor Air Temperature to verify the heating is enabled to run
due to cool temperatures.
d. If you have Economizer control, the Economizer must be at its minimum
ventilation position.
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 heating stages currently running. )