Application

Sequence of Operation
Control Temperature Setpoints
7
Siemens Industry, Inc. Application Note, App 2033 140-1023
2015-08-07
The setpoint deadband exists to allow the controller to provide a separation of the
heating and cooling temperature setpoints when a setpoint dial is enabled.
The setpoint deadband is the difference between the cooling and heating day setpoints
(DAY CLG STPT - DAY HTG STPT). The setpoint deadband can be disabled by
setting DAY HTG STPT equal to DAY CLG STPT. When DAY HTG STPT does not
equal DAY CLG STPT, a setpoint deadband (or zero energy band) is used.
The following values are used in the calculation of CTL STPT:
 Dial value is the value of RM STPT DIAL limited between the value of RM STPT
MIN and RM STPT MAX.
 Deadband is the value of the difference between DAY CLG STPT and DAY HTG
STPT, half of which is applied to establish the current heating and cooling
setpoints.
–
Deadband = (DAY CLG STPT – DAY HTG STPT)
CTL STPT is calculated as follows:
With Deadband disabled:
CTL STPT = Dial value
With Deadband enabled in Heat Mode:
CTL STPT = Dial value – 0.5 ∗ Deadband (limited between the value of RM STPT MIN
and RM STPT MAX)
With Deadband enabled in Cool Mode:
CTL STPT = Dial value + 0.5 ∗ Deadband (limited between the value of RM STPT MIN
and RM STPT MAX)
NOTE:
If RM STPT DIAL is failed, it maintains the last known value.