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Modulating Modbus Room and FCU Controllers | HLS34 HLS34 Intelligent Modbus Room Controller

HLS34 fan coil unit controllers are suitable for wide range of fan coil unit applications including 2-pipe and 4-pipe FCUs with automatic demand based fan speed control, and for air-side control applications. HLS34 controllers have unique capability of boosting the fan speed based on the room space air quality (CO2 measurement). This is particularly effective feature when the FCUs are connected to fresh air duct work or are mounted on the outside wall with fresh air inlet. Controllers can also be configured for VAV control with CO2 fresh air control.

The HLS34 controllers have very easy to understand LCD display and unique MagicTouch™ buttons for user settings. HLS34-S1 allows the users to adjust the room setpoint by pressing + and - buttons and to provide day extension. HLS34-S2 has additional fan speed control override button. The user setpoint adjustment range is limited at the commissioning to a range, typically +/-3 degrees. When the HLS34 controller goes into night mode (reduced setpoint) and returns back to day mode, it has an option to reset the user adjustment offering key energy saving features.

The HLS34 is controlled between day and reduced night setpoints via a local hard-wired presence switch such as PIR, or over the network from the central interface. When in the night mode the controller can be overriden to the day mode by the user for a specified time by pressing the Day Extension button.

The HLS34 controller controls the temperature to the required setpoint by modulating the heating and/or cooling valves. The controller has capability of using thermic, 3-point and 0-10Vdc fully modulating actuators making accurate control possible.

The HLS34-S3 model has been designed for air-side control applications, where the control valve output is required to be at 50% position when at the setpoint. The air-side control applications use a damper to divert the air flow through a heating coil or cooling coil, and are widely used in the UK.

The diagram below illustrates the temperature control logic for the 2-pipe and 4-pipe fan coil unit applications..

HLS34 Operation Diagram  
HLS34 Overview, Comparison Tables and Networking Capabilities