Delta Controls BACstat III DNT-T221-FCU, Application Manual

Page: 15 / 30

Document Edition 1.3
Page 15 of 30
Software Controller Loop
General
The operation of the BACstat III is centered on a software controller. The controller uses the following
parameters in its operation.
Parameter Object Default Value Notes
Room Temperature AI1 N/A Input 1
Temperature
Setpoint Occupied: Uses Day Setpoint (AV6)
Unoccupied: Uses Night Heat Setpoint (AV10) if
the Input is below the Night Heat Setpoint (AV6);
Uses the Night Cool Setpoint (AV11) if the Input is
above the Night Cool Setpoint (AV6);
Otherwise it is in a null zone.
Proportional Band AV19 2.0 ºF / 1.0 ºC Degrees F or C as configured for AI1
Reset Rate AV20 1.0 Resets per hour
Day Differential AV9 1.0 ºF / 0.5 ºC Degrees F or C as configured for AI1
Controller Operation
Heating
Setpoint
-100%
Cooling
Heating
Day Setpoint
Cooling
Setpoint
Day
Differential
Deadband
Proportional Band Proportional Band
Controller
Output
(Cooling)
0%
100%
Controller
Output
(Heating)
0%
Temperature
Normal Controller Action
Deadband is a span of 0.2 around setpoint (heating or cooling) over which neither heating nor cooling
takes place.
Here are a few rules and restrictions to how the internal Loop Controller functions:
•
Heating and Cooling will not be On at the same time
•
If the Input temperature is less than ( Day Setpoint – ( Day Differential + ½ Deadband )) then the
controller is in Heating
•
If the Input temperature is greater than ( Day Setpoint + ( Day Differential + ½ Deadband )) then the
controller is in Cooling