On 2-pipe applications, the thermostat controls a valve in heating / cooling mode with changeover (automatically or manually), heating only, or cooling only. Cooling only is factory-set (P01 = 1).
ON/OFF control
Control sequence
ON/OFF output
The diagrams below show the control sequence for 2-position control.
| Heating mode | Cooling mode |
 |
 |
| T[°C] Room temperature | SDH Switching differential “Heating” (P30) |
| w Room temperature setpoint | SDC Switching differential “Cooling” (P31) |
| V1 Control command “Valve” or “Compressor” |
Modulating control: 3-position
Control sequence modulating output
The diagrams below show the control sequence for modulating PI control.
| Heating mode | Cooling mode |
 |
 |
| T[°C] Room temperature | XpH Proportional band “Heating” (P30) |
| w Room temperature setpoint | XpC Proportional band “Cooling” (P31) |
| V1 Control command “Valve” |
Note:
The diagrams only show the PI thermostat’s proportional part.
Setting the sequence and the control outputs
Refer to sections 3.4 "Applications", 3.6.1 "Sequences", and 3.7 "Outputs".