User Manual

Sequence of Operation

Control Temperature Setpoints

Siemens Industry, Inc.

Application Note, App 14900

140-1231

2020-02-11

Sequence of Operation

The following paragraphs show the sequence of operation for Application 14900.

Control Temperature Setpoints

This application has a number of different room temperature setpoints

(ComfortHtgSP, EconHtgSP, ComfortClgSP, and EconClgSP). The setpoint can be

temporarily overridden for a period of time (default is 30 minutes). The application

controls using the effective setpoint (EFF STPT). EFF STPT is set to different values

depending on its HVAC Mode (Cooling, Heating, or Neutral), override status, and the

time of day.

CoolingSp : Cooling Setpoint

CoolingDB: Cooling Deadband

CoolingDB is divided equally above and below CoolingSp; therefore, (CoolingSp +

1/2 CoolingDB) is the switching on point of the first cooling stage, and (CoolingSp –

1/2 CoolingDB) is the switching off point of the first cooling stage.

HeatingSp: Heating Setpoint

HeatingDB: Heating Deadband

HeatingDB is divided equally above and below HeatingSp; therefore, (HeatingSp –

1/2 HeatingDB) is the switching on point of the first heating stage, and (HeatingSp +

1/2 HeatingDB) is the switching off point of the first heating stage.

StgDifCl: Cooling Inter-stage Differential

(CoolingSp + 1/2 CoolingDB+ StgDifCl) is the switching on point of the second

cooling stage, and (CoolingSP – 1/2 CoolingDB+ StgDifCl) is the switching off point

of the second cooling stage.

StgDifHt: Heating Inter-stage Differential

(HeatingSp – 1/2 HeatingDB – StgDifHt) is the switching on point of the second

heating stage, and (HeatingSp + 1/2 HeatingDB – StgDifHt) is the switching off point

of the second heating stage.

CLG SPAN: Cooling SPAN combined ∆T of all stages of cooling,

CLG SPAN is derived from other parameters. For single-stage cooling: CLG SPAN =

CoolingDB; For multi-stage cooling: CLG SPAN = CoolingDB + StgDifCl*n (where n

represents the number of stages of additional cooling.)

HTG SPAN: Heating SPAN combined ∆T of all stages of heating, HTG SPAN is

derived from other parameters. For single-stage heating: HTG SPAN = HeatingDB;

For multi-stage heating: HTG SPAN = HeatingDB + StgDifHt*n (where n represents

the number of stages of additional heating.)

CLG SPAN or HTG SPAN indicates how the bias between room temperature and room

setpoint could possibly be due to the characteristic of hysteresis control.