Auto-Zone Control Systems Auto-Zone CV-C Controller Installation Guide (Version 01A) - Manual (Page 29)

Auto-Zone CV-C Section 2
Sequence of Operation 2-19
Once the Hot Water Valve is enabled for operation, the actual valve position is calculated
using a Proportional, Integral and Derivative (PID) formula. All three formula constants
are user adjustable along with a fourth setpoint for the Integrating Interval. There are
defaults programmed in the code that should not be changed unless the user, through
actual observation, has determined that the valve is hunting or is not operating quickly
enough to maintain a constant Supply Air Temperature.
A later section entitled PID Operation can be referred to for an actual example of code
that does the valve positioning. This formula applies to both Chilled Water and Hot
Water Valve operations.
Fan Control Fan Control Fan Control Fan Control
The Fan runs continuously in the occupied mode and cycles on and off with the heating
or cooling in the unoccupied mode unless the user configures it for the Fan Cycle Mode.
In this mode, the Fan will start before any other outputs can be activated. It must have
been off for at least one minute before it can be restarted.
Once the fan has been commanded to turn off, it first checks to see if all heating and
cooling stages are off or valves are closed. If everything has been off for at least 30
seconds, the fan is allowed to stop.
If the user has entered the Fan Only force mode, this will be the only active output and all
scheduling or anything else that normally affects the fan will be ignored until the Fan
Only mode is removed.
WARNING: The Fan Only mode does not automatically clear itself. The user must
remove this force command or the fan will never turn off and no
heating or cooling will occur!