Heating-cooling relay with 4 channels, 1 normally open contact 4A/250V AC each, electrically isolated from the supply voltage, with DX technology. Bidirectional. Stand-by loss only 0.1 watts. Modular device for mounting on DIN-EN 60715 TH35 rail. 1 division unit = 18mm wide, 58mm deep. Connection to the Eltako RS485 bus. Cross-wiring of bus and power supply with jumper. With the patented Eltako duplex technology, the normally potential-free contacts can still switch at zero crossing when switching 230V AC 50Hz, thereby drastically reducing wear. To do this, simply connect the N conductor to terminal (N) and L to K (L). This results in an additional stand-by loss of only 0.1 watts. If all 4 relays are switched on, 0.7 watts are required. If the supply voltage fails, the system is switched off in a defined manner. This heating-cooling relay evaluates the information from wireless temperature controllers or sensors. Possibly supplemented by window-door contacts, motion detectors, window handle sensors FFG7B and wireless buttons. As an alternative to a wireless temperature controller, the temperature information on setpoint and actual values can also be obtained from a Professional Smart Home Controller. It is also possible to specify the setpoint temperature via the Professional Smart Home Controller and thus limit the setting range of the wireless temperature controller. Upper rotary switch for the adjustable hysteresis: Left stop: smallest hysteresis 0.5º. Middle position: hysteresis 2.5º. Right stop: largest hysteresis 4.5º. In between, subdivision in 0.5º steps. Middle rotary switch for the control types: AUTO 1: With PWM control with T = 4 minutes (PWM = pulse width modulation). (Suitable for valves with thermoelectric actuators). AUTO 2: With PWM control with T = 15 minutes. (Suitable for valves with motor actuators). AUTO 3: With 2-point control. Lower rotary switch for the operating modes: H: Heating mode (contacts 1 to 4), K: Cooling mode (contacts 1 to 4). HK: Heating mode (contacts 3 and 4) and cooling mode (contacts 1 and 2). In heating mode, the frost protection function is always active. As soon as the actual temperature falls below 8°C, the selected operating mode is regulated to 8°C. As long as one or more windows are open, the output remains off, provided that window/door contacts FTK or window handle sensor FFG7B have been taught in. In heating mode, however, the frost protection remains active. As long as all taught-in motion detectors FBH have not reported any movement, the system switches to setback mode. In heating mode, the target temperature is reduced by 2°, in cooling mode it is increased by 2°. As soon as a motion detector detects movement again, the system switches to normal operation. If a radio button FT4 is programmed, the 4 buttons are assigned the following functions: Top right: Normal operation (can also be activated by timer). Bottom right: Night-time reduction operation by 4°,In cooling mode, the temperature is raised by 4° (can also be activated using a timer). Top left: Reduced mode by 2°, in cooling mode, the temperature is raised by 2°. Bottom left: Off (frost protection active in heating mode, permanently off in cooling mode). If a motion detector and a radio button are programmed at the same time, the last telegram received always applies. When a motion detector detects movement, it switches off a reduced mode selected using the radio button. The LED under the upper rotary switch accompanies the programming process in accordance with the operating instructions and indicates control commands during operation by flashing briefly.