Modular device for DIN-EN 60715 TH35 rail mounting. 1 module = 18mm wide, 58mm deep.

State-of-the-art hybrid technology combines advantages of nonwearing electronic control with

high capacity of special relays.

Connection to the Eltako RS485 bus, terminals RSA and RSB.

Up to a total of 128 actuators can be added in this way.

Patented Eltako Duplex technology (DX) allows you to switch normally potential free contacts

in zero passage switching when 230V A/C voltage 50Hz is switched. This drastically

reduces wear. To achieve this, simply connect the N conductor to the terminal (N) and L to

1(L) and/or 3(L). This results in an additional standby consumption of only 0.1 watt.

The 12V DC supply voltage of the complete RS485 bus is mainly powered at 6W, 12W or

24W by a switch mode power supply unit SNT12-12V DC that is only 1 or 2 pitch units wide.

When both relays of the FHK12 are switched on, 0.5 watts are required.

This heating/cooling relay assesses information about wireless temperature controllers or sensors.

Possibly supplemented by window/door contacts, motion detectors, Hoppe window handles

and wireless pushbuttons.

Top rotary switch for adjustable hysteresis:

Left stop:

lowest hysteresis 0.5º. Middle position: hysteresis 2.5º.

Right stop:

largest hysteresis 4.5º. Inbetween, divisions in steps of 0.5°.

Middle rotary switch for regulation types:

AUTO 1:

With PWM control at T = 4 minutes. (PWM = pulse width modulation).

(suitable for valves with thermoelectric valve drive)

AUTO 2:

With PWM control at T = 15 minutes. (suitable for valves with motor-driven valve drive)

AUTO 3:

With 2-point control.

Bottom rotary switch for operating modes:

H:

heating mode (Contacts 1-2 and 3-4); K: cooling mode (Contacts 1-2 and 3-4);

HK:

heating mode (Contact 3-4) and cooling mode (Contact 1-2)

Two-point control mode:

The hysteresis rotary switch sets the required difference between the switch-on and switch-off temperatures.

When the 'actual temperature >= reference temperature', the device is switched off. When the 'actual temperature <= (reference

temperature – hysteresis)', the device is switched on. The signs are the opposite in cooling mode.

PWM control mode:

The hysteresis rotary switch set the required temperature difference at which the device is switched on at

100%. When the 'actual temperature >= reference temperature', the device is switched off.

When the 'actual temperature <= (reference temperature – hysteresis)', the device is switched on at 100%. If the 'actual temperature'

lies between the 'reference temperature – hysteresis' and the 'reference temperature', the device is switched on and off with a

PWM in steps of 10% depending on the temperature difference. The lower the temperature difference, the shorter the switch-on

time. As a result of the settability of the 100% value, the PWM can be adapted to the heater size and inertia. The signs are the

opposite in cooling mode.

In heating mode, the

frost protection function is always enabled. As soon as the actual temperature drops below 8°C, the temperature

is controlled in the selected operating mode to 8°C.

If one or several windows are open, the output remains off

provided the window/door contacts FTK or Hoppe window handles are

taught-in. In heating mode, however, the frost protection remains enabled.

As long as all taught-in

motion detectors FBH detect no motion, the device is switched to setback mode. In heating mode, the

reference temperature is set back by 2°; in cooling mode, it is raised by 2°. As soon as a motion detector signals movement

again, the device is switched to normal mode.

When a

wireless pushbutton FT4 is taught-in, the assignment of the 4 keys is assigned with the following fixed functions:

Top right: Normal mode (can also be enabled by timer). Bottom right: Night setback mode by 4°; in cooling mode, raised by 4°

(can also be enabled by timer). Top left: Setback mode by 2°, in cooling mode, raised by 2°. Bottom left: Off (in heating mode,

frost protection enabled; in cooling mode permanent off). If the motion detector and wireless pushbutton are taught-in at the

same time, the last telegram received is always the one that is valid. A motion detector therefore switches off a setback mode

selected by wireless pushbutton when a movement is detected.

The LED

below the upper function rotary switch performs during the teach-in process according to the operation manual. It shows

control commands by short flickering during operation.