﻿#HVAC

The device enables the electrical control of up to two fan coil units (FanCoil units). Fan coil units are used to heat or cool rooms depending on the requirements. They can be installed, just like conventional radiators, anywhere a central heating and/or cooling system is installed.
Depending on the design of the device, fan coil units are used in two-pipe systems (heating only, cooling only, or heating and cooling by means of a shared piping system) or in four-pipe systems (heating and cooling by means of separate pipes). The device supports both pipe principles.

As a rule, the device receives command value telegrams, for example from the internal or an external room temperature controller, and converts these command value specifications into equivalent fan levels. In addition, the device controls the valves in the fan coil unit, either by means of an operating mode specification or, alternatively, directly by separate command value specifications to open or close the heating or cooling line(s) depending on the requirements.
The device also allows manual activation of the blower fan, thus enabling purely ventilation functions without heating or cooling, or individual room ventilation with heating or cooling active. This function is attractive, for example, for hotel rooms or classroom and office spaces. Manual control can be carried out by means of push-button sensors or control panels or the extension inputs of the device.
The fans can be controlled either by switching via relay outputs or constantly via 0...10 V outputs.

Electrothermal valve drives (ETA) for heating or cooling systems can be controlled via 1 bit (relay outputs) or 1 byte (relay outputs or dimming outputs) or constantly via 0...10 V outputs. When controlling via relay outputs and dimming outputs, continuous command value telegrams are controlled in a pulse width modulated output signal (PWM). This enables quasi-continuous control of the connected valve drives. 
