CNT-SVX05A-EN
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Sequence of operation
The capacity calculation, as a result of the discharge air control loop, is used to
drive the air handling unit's actuators to maintain space temperature at the
space temperature setpoint.
Figure 7 — Space temperature control block diagram
Control gains
Figure 7 above illustrates the separate control for the space temperature control
loop and discharge air control loop. The gain parameter values that control the
different loops have been determined through extensive testing of different
types of heating or cooling capacities and at operating conditions of the air
handling unit.
Heating or cooling control mode operation
The heating or cooling control mode of the controller can be determined two
ways:
• Communicated request
• Automatically by the controller
Communicated request
A building automation system or peer controller may communicate the heating
or cooling mode to the controller via network variables nviHeatCool and/or
nviApplicMode. Heating mode commands the controller to heat only. Cooling
mode commands the controller to cool only. The Auto mode allows the
controller to automatically change from heating to cooling or cooling to heating.
Refer to the Appendix, Table 63
Constant volume space temperature control
operation based on the effective heat/cool output
.
Space temperature
→
Space temperature setpoint
→
Space temperature control loop
Space temperature control gains
→
Discharge air temperature setpoint limits
→
↓
Discharge air temperature setpoint
↓
Discharge air temperature
→
Discharge air control loop
↓
Discharge air control gains
→
Calculate heat/cool capacity
↓
Use capacity to drive actuators
