Auto-Zone Control Systems Auto-Zone CV-C Controller Installation Guide (Version 01A) - Manual (Page 23)

Auto-Zone CV-C Section 2
Sequence of Operation 2-13
Chilled Water Valve Chilled Water Valve Chilled Water Valve Chilled Water Valve
Operation
Operation Operation Operation
If the user has configured the CVC with the Chilled Water Valve 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 the valve modulation signal is 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.
If you have configured the system to control De-Humidification with the Chilled Water
Valve then the valve will modulate open at a user defined rate 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 valve
can modulate closed. If there is still a cooling demand in the space then the valve will still
modulate to maintain a user defined supply air temperature.
Ignoring the Humidity Control for the moment, the chilled water valve operates as
follows:
a. A cooling demand equal to the Cooling Setpoint plus half the Deadband has
occurred in the space.
b. If the cooling mode is enabled by outside air, then the valve modulates to
maintain a supply temperature, defined by the user, until the demand drops