Room thermostat, AC 24 V, VAV heating and cooling systems

Stock no. S55770-T164

Stock no. S55770-T164

  • KNX communications

  • Output DC 0…10 V for VAV actuator and auxiliary output ON/OFF, PWM or 3-position or 3-position for VAV actuator and auxiliary output DC 0...10 V

  • 3 multifunctional inputs for keycard contact, external room / return air temperature (1x, QAH11.1, QAA32), heat / cool changeover, operation mode changeover, window contact on/oQAH11.1ff, dewpoint monitor, electrical heater enabled, fault contact

  • Operating modes: Comfort, Energy Saving and Protection

  • Modulating PI control

  • Control depending on the room or the return air temperature

  • Automatic or manual heating / cooling changeover

  • Adjustable commissioning and control parameters

  • Minimum and maximum setpoint limitation

  • Minimum and maximum limitation of air flow signal

  • Output signal inversion (DC 0...10 V) as an option

  • Backlit display

Application selectable:

  • Single-duct system

  • Single-duct system with electrical heater

  • Single-duct system and radiator / floor heating

  • Single-duct system with heating / cooling coil



Operating voltage

AC 24 V


50/60 Hz

Power consumption

2 VA

Positioning signal

DC 0...10, 3-position V

Control algorithm

P / PI

Ambient temperature, operation

0...50 °C

Setpoint setting range

5…40 °C

Measuring range, temperature

0…49 °C

Switching differential

Heating: 0.5…6 K
Cooling: 0.5…6 K

Analog inputs

External room / return air temperature, Heat / Cool changeover, Operation mode changeover, Window contact on/off, Dewpoint monitor, Electrical heater enabled

Analog inputs, number


Analog outputs

VAV actuator, electric heater, valve

Analog outputs, number


Analog output, signal

DC 0...10 V

Analog output, current

Max. ±1 mA

Digital inputs, number


Triac outputs

VAV actuator, valve, el. heater, 2-position, PWM, 3-position

Triac outputs, number


Triac output, switching voltage

AC 24 V

Triac output, switching current

Max. 1 A

Mounting position

Wall mounting


Wall mounting with screws

Type of fixing

Wall mounting with screws

Degree of protection


Dimensions (W x H x D)

93 x 128 x 30.8 mm