This block controls fan coil units, typically used in commercial buildings and hotels.
Based on the current room temperature (ϑc) and target temperature (ϑt), the air volume is regulated via a PI controller.
The heating and cooling valves are controlled based on the demand.
Table of Contents
Inputs↑
| Abbreviation | Summary | Description | Unit | Value Range |
|---|---|---|---|---|
| ϑc | Current Room Temperature | Value will be provided by connected Intelligent Room Controller | ° | ∞ |
| ϑt | Target Room Temperature | Value will be provided by connected Intelligent Room Controller | ° | ∞ |
| Ha | Heating Available | Specifies if the heating source is available. TRUE if not connected. | - | 0/1 |
| Ca | Cooling Available | Specifies if the cooling source is available. TRUE if not connected. | - | 0/1 |
| Dwc | Door and Window Contact | 0 = Closed 1 = Open | - | 0/1 |
| Rtd | Reset to default | Resets parameters and settings of the block to the default values as specified in the block preset. | - | 0/1 |
| Off | Off | Pulse: Turns Fan and Valves Off. On: All outputs to off, resets timers and locks the block. Dominating input. | - | 0/1 |
| Sm | Silent Mode | When activated, maximum fan speed is set according to the "Silent Mode Fan Speed" setting. When deactivated again, the fan speed will be recalculated. | - | 0/1 |
| Bm | Boost Mode | Sets the fan speed to maximum. | - | 0/1 |
| Pt | Pause Timer | Pauses the device for the duration set in parameter (Ptd). | - | 0/1 |
| Fan | Fan Speed | Fan speed in percentage of full power. -1 for Auto. -1 if not connected. | % | -1...100 |
Parameters↑
| Abbreviation | Summary | Description | Unit | Value Range | Default Value |
|---|---|---|---|---|---|
| Fmax | Maximum Fan Speed in Auto Mode | % | 0...100 | 80 | |
| Mode | Mode | 0 = Off 1 = Auto 2 = Heating 3 = Cooling 4 = Ventilation If set to Auto and controlled by IRC, it will be set by IRC | - | 0...4 | 1 |
| Ptd | Pause Timer Duration | Starts with the rising edge of input (Pt). Keeps the device paused for the specified duration. | s | 0...∞ | 7200 |
| FϑKP | Proportional Gain (Fan) | Proportional Gain for Fan output based on Temperature. Used for PI Controller. | - | 0...∞ | 50 |
| FϑKI | Integral Gain (Fan) | Integral Gain for Fan output based on Temperature. Used for PI Controller. | - | 0...∞ | 0.01 |
| FϑSt | Sample Time (Fan) | Sample Time for Fan output based on Temperature. Used for PI Controller. | s | 0...∞ | 60 |
Outputs↑
| Abbreviation | Summary | Description | Unit | Value Range |
|---|---|---|---|---|
| H | Heating Output | - | 0...10 | |
| C | Cooling Output | - | 0...10 | |
| HC | Combined Heating/Cooling Output | - | 0...10 | |
| Fan | Fan Speed Analogue | - | 0...100 | |
| FanS | Fan Speed Step | Current step calculated with "Fan Speed Steps" setting. | - | 0...∞ |
| ϑc | Current Room Temperature | ° | ∞ | |
| ϑt | Target Room Temperature | ° | ∞ | |
| Mode | Current Mode | 0 = Off 1 = Auto 2 = Heating 3 = Cooling 4 = Ventilation | - | 0...4 |
| S | Status | On when either valve is open or fan is active. | - | 0/1 |
| API | API Connector | Intelligent API based connector. API Commands | - | - |
Properties↑
| Summary | Description | Unit | Value Range | Default Value |
|---|---|---|---|---|
| Fan speed steps | For mapping discrete steps. Example: 4 steps -> 25% of full power for each step | - | 0...100 | 3 |
| Silent mode fan speed | Maximum fan speed in silent mode | % | 0...100 | 10 |
Functional Description↑
This block regulates the air volume as well as heating and cooling output based on the current temperature and target temperature.
The air volume is only increased as necessary to maintain the target temperature, since higher air volumes lead to higher energy losses.
The outputs are controlled according to the following operating logic:
| Operating Mode | Air Volume | Heating Output | Cooling Output |
|---|---|---|---|
| Heating | ϑ variable | 100 % | Everything OK |
| Cooling | ϑ variable | Everything OK | 100 % |
| Everything OK | Everything OK | Everything OK | Everything OK |
ϑ variable
The air volume is adjusted depending on the difference between current temperature and target temperature.
The heating or cooling output operates at full capacity.
 | To ensure stable and non‑disruptive control, the air volume is adjusted once per minute, with changes limited to a maximum of 20%. As a result, a full adjustment from 100% to 0% requires five minutes. |
Programming Example↑
Combination with Intelligent Room Controller
The heating and cooling valves as well as the fan are connected to the corresponding outputs of the block.
The Fan Coil Unit Controller can be connected to the Intelligent Room Controller via the API Connector:
In the properties window, the PI controller parameters for the temperature-based fan regulation can be adjusted:
Since this example uses a 4-pipe system, the inputs (Ha) and (Ca) do not need to be connected, as heating and cooling are assumed to be available by default.
The Intelligent Room Controller handles the room logic and passes temperature values and heating/cooling requirements to the Fan Coil Unit Controller.
This adjusts the air volume and heating/cooling valves.
Combination with Intelligent Room Controller and Fan Coil Central Controller
By double-clicking the central block, the corresponding Fan Coil Unit Controllers can be added:
In the properties window, the system type (2-pipe or 4-pipe) can be selected directly:
The Fan Coil Central Controller gathers the demands and decides between heating and cooling.
Based on this decision, the Fan Coil Unit Controllers adjust the valves and air volume in the respective rooms.
This block can also operate standalone. In this case, temperature values are passed directly to the block via the inputs..