Space temperature control
CNT-SVX05B-EN 33
Figure 9. Space temperature control block diagram
Communicated request
A building automation system or peer controller may communicate the
heating or cooling mode to the controller via network variables nviHeat-
Cool 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 cool-
ing or vice versa. See Table 71 on page 101 for more information.
Table 15 shows space temperature control based on communicated
request. Enabled means normal operation; disabled means that the con-
troller cannot use the request.
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 temperature control gains → Calculate heat/cool capacity
↓
Use capacity to drive actuators
Table 15. Space temperature control based on communicated request
Request
1
Supply fan
Mechanical
heating
Mechanical
cooling
Outdoor air damper Exhaust fan
Auto Enabled Enabled Enabled Enabled Enabled
Heat Enabled Enabled Disabled Enabled Enabled
Morning
warm-up
Enabled Enabled Disabled Closed Disabled
Cool Enabled Disabled Enabled Enabled Enabled
Night purge Enabled Disabled Disabled Ventilation disabled
Economizer enabled
Enabled
Pre-cool Enabled Disabled Enabled Ventilation disabled
Economizer enabled
Disabled
Off Disabled Disabled Disabled Disabled Disabled
Test Enabled Enabled Enabled Enabled Enabled
Emergency
heat
2
Enabled Enabled Enabled Enabled Enabled
Fan only Enabled Disabled Disabled Disabled Enabled
1 Enabled means the operation is normal. Disabled means that the controller cannot use the request.
2 The Tracer AH540/541 controller does not support emergency heat. The controller will treat emergency heat as Auto.
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