Climate control > Clock thermostats > OpenTherm > RAMSES 856 top2 OT

RAMSES 856 top2 OT


  • Digital heating control for time-dependent monitoring and control of room temperature
  • Open Therm heating controller for 2 or 3 point control, weather-dependent, service water and circulation control
  • Automatic sensor recognition for weather- or room-dependent control; can be switched manually at any time
  • 3 different weekly programs
  • 3 comfort and 2 reduced temperatures can be allocated to each phase
  • INFO button for the most important data
  • Additional switching program for domestic hot water utilisation times
  • Adjustable service water storage temperature, programmable legionella protection
  • Party/ECO program
  • Chimney sweeping function with push button OT box
  • Minimum boiler temperature can be set
  • 2 heating curves can be set for 2 heating circuits
  • 2-stage burner control option
  • Holiday program with reduced temperature or date-controlled heating phase can be programmed e. g. for holiday homes
  • USB interface for modem
  • Automatic summer/winter time adjustment
  • Boiler/feed temperature (control circuit 1) controlled by switching the burner
  • Control of feed temperature (control circuit 2) via pump control or motor-controlled mixer
  • 3-point controller with feed sensor
  • Time- and temperature-dependent control of hot water circulation pump.
  • Pump protection function
  • Inputs: External sensor (contained in set), feed sensor heating circuit (contained in set), contact or immersion sensor for domestic hot water, contact sensor for circulation
  • Elapsed-time counter for recording relay switching times e.g. burner operating time
  • Adjustable reminder function for heater maintenance

Technical data

Operating voltage 230 V AC
Frequency 50 Hz
Type of contact NO contact
Installation type Wall installation
Switching capacity

5 x 5 (1) A Relay, 2 x 1 (1) A Relay:

Setting range temperature +6 °C … +30 °C
Setting range frost protection +6 °C … +15 °C
Flow temperature limit +40 °C … +90 °C
Type of connection 2-way conductor (BUS) room controller
Program Weekly program, Daily program
Number of memory locations 42 , max. 24 per program
Switching hysteresis 2 – 20 K
Mixer runtime 2 – 10 min
Suitable for SELV No
Control types 2 or 3 point
Mode of operation Type 1 B as per EN 60730-1
Power reserve 4 hours
Stand-by consumption ~1,1 W
Type of protection IP 20
Protection class II according to EN 60 730-1

Connection example

RAMSES 856 top2 OT
RAMSES 856 top2 OT
RAMSES 856 top2 OT
RAMSES 856 top2 OT

Scale drawings

RAMSES 856 top2 OT


Article number Data sheet Documents basket
Temperature sensor RAMSES IP 65 - External room temperature sensor

Temperature sensor RAMSES IP 65

Flow temperature sensor RAMSES - Also required for applications with 2 feed sensors

Flow temperature sensor RAMSES

OT-Box Standard - For expansion of the RAMSES 856 top2 OT system

OT-Box Standard

Plunge sensor RAMSES - Additionally required for applications with domestic water control or boiler plunge sensor

Plunge sensor RAMSES



Format Download
Operating instructions PDF
RAMSES 856 top2 OT - Digital heating control for time-dependent monitoring and control of room temperature

RAMSES 856 top2 OT

Article number 8569132
Data sheet
Documents basket