In 2-pipe applications, the thermostat controls a valve in heating/cooling mode with changeover (automatically or manually), heating only, or cooling only (factory setting, P02 = 1).

On/Off control

Control sequence
On/Off control output

The diagrams below show the control sequence for On/Off control.

Heating mode

Cooling mode

T[°C]   Room temperature

SDH    Switching differential "Heating"
           (P40)

w        Room temperature setpoint

SDC    Switching differential "Cooling"
           (P41)

YHC   Control command "Valve"