Space temperature control
CNT-SVX05B-EN 37
For example, assume the controller is configured with the following
default setpoints:
• Unoccupied cooling setpoint 85°F (29.4ºC)
• Occupied standby cooling setpoint 76°F (24.4ºC)
• Occupied cooling setpoint 74°F (23.3ºC)
• Occupied heating setpoint 70°F (21.1ºC)
• Occupied standby heating setpoint 66°F (18.9ºC)
• Unoccupied heating setpoint 60°F (15.6ºC)
Absolute Setpoint Offset = Setpoint Input – Mean Setpoint
From the default setpoints in this example, the mean setpoint is the
mean of the occupied cooling and heating setpoints, which is 72°F
[(74+70) / 2]. The absolute setpoint offset is the difference between the
setpoint input and the mean setpoint.
Assume a thumbwheel setpoint input of 73°F, resulting in an absolute
setpoint offset of 1°F (73–72=1). The controller adds the absolute setpoint
offset (1°F) to occupied and occupied standby default setpoints to derive
the effective setpoints, as follows.
• Unoccupied cooling setpoint 85°F (same as default)
• Occupied standby cooling setpoint 77°F (default+1=77)
• Occupied cooling setpoint 75°F (default+1=75)
• Occupied heating setpoint 71°F (default+1=71)
• Occupied standby heating setpoint 67°F (default+1=67)
• Unoccupied heating setpoint 60°F (same as default)
When a building automation system or other controller communicates a
setpoint to the controller, the controller ignores the hard-wired setpoint
input and uses the communicated value. The exception is the unoccupied
mode, when the controller always uses the stored default unoccupied set-
points.
After the controller completes all setpoint calculations based on the
requested setpoint, the occupancy mode, the heating and cooling mode,
and other factors, the calculated setpoint is validated against the follow-
ing setpoint limits:
• Heating setpoint high limit
• Heating setpoint low limit
• Cooling setpoint high limit
• Cooling setpoint low limit
These setpoint limits only apply to the occupied and occupied standby
heating and cooling setpoints. These setpoint limits do not apply to the
unoccupied heating and cooling setpoints stored in the controller configu-
ration.
Unit configuration also exists to enable or disable the local (hard-wired)
setpoint at the zone sensor module. This parameter provides additional
flexibility to allow you to apply communicated, hard-wired, or default set-
points without having to make physical wiring changes to the controller.
To Next Page
Loading...
Need help?
General
