KMC Controls BAC-8007 Installation Guide - Manual (Page 61)

Standby setpoint —The standby setpoint is used when the controller is in the
standby state. It is a value calculated from the occupied setpoint and the value
of Standby Offset. The standby offset value is entered by the controls
technician during controller setup and system commissioning. See the topic
Occupancy sequence on page 59 .
Setpoint limits
The programming in the SimplyVAV controller limits the setpoint entry so
that no heating setpoint is set higher than its corresponding cooling setpoint.
If a user is adjusting a setpoint and it falls within the range set by the value of
Minimum Setpoint Differential, the corresponding setpoint will be changed to
maintain the differential. For example, the Minimum Setpoint Differential is
4° F and the Occupied Heating setpoint is 70° F. If the user lowers the
Occupied Cooling setpoint to 71° F, the controller recalculates the Occupied
Heating setpoint and changes it to 67° F.
PID control loops A PID control loop calculates an error value from the difference between the
measured room temperature and the active setpoint. The error value is
expressed as a percentage and is typically used in a BAS controller to control
the state of an output. When the difference between the setpoint and room
temperature is large, the error is large. As the system reduces the difference
between the setpoint and space temperature, the error becomes smaller.
The SimplyVAV controllers use up to three PID loops.
The heating PID loop.
The cooling PID loop.
The discharge air temperature (DAT) loop.
For SimplyVAV controllers, the output of either the cooling and heating PID
loop is used to calculate the position of the damper. If present, the DAT input
and DAT loop controls the Reheat loop.
The PID loops in the SimplyVAV controllers are standard BACnet objects and
are described in the topic
BACnet objects on page 77 .
Airflow setpoints
sequence Airflow Setpoint is calculated based on the demand for cooling or heating
depending on whether the Cooling loop or Heating loop is greater than zero.
If no room sensor is connected to the controller, the controller uses the
Minimum Cooling Airflow setpoint to maintain airflow.
Cool Air Sequence As the Cooling loop increases from 0% to 100%, Primary
Airflow Setpoint is proportionally calculated between Minimum Cooling
Airflow and Maximum Cooling Airflow.
SimplyVAV Section 7: Sequences of operation
Revision E 61