Category
HVAC Room & Zone Controllers
Room controllers and control units for temperature, CO2 and ventilation control in buildings.
HVAC building controllers read room sensors, compare them with a setpoint and drive valves, dampers and fans locally, while reporting status to the BMS. Produal offers two families here: HLS 44 room controllers for single-room temperature and VAV control, and Proxima CU zone control units with Modbus RTU, Modbus TCP, BACnet MS/TP and BACnet IP for more complex zones.
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Selection guide
HVAC Room & Zone Controllers Guide
What an HVAC building controller does
A building controller reads its room sensors, compares them with the configured setpoint, and drives valves, dampers and fans locally to keep the space comfortable, while reporting status and accepting overrides from the BMS. That local decision-making keeps the room stable even if the network link to the BMS is briefly lost, which a purely centralised control scheme can't do.
How to choose between a room controller and a control unit
- Number of rooms: an HLS 44 room controller handles one room. A Proxima control unit can control two rooms from one device.
- Protocol: HLS 44 and the CU-LH-MOD use Modbus RTU only. The Proxima CU adds Modbus TCP, BACnet MS/TP and BACnet IP, for BMS platforms that need BACnet.
- I/O flexibility: HLS 44 has fixed inputs and outputs sized for a single room. The Proxima CU has 6 universal inputs (NTC10, Pt1000, resistive, digital or 0 to 10 VDC) and 6 universal outputs (0 to 10 VDC, 4 to 20 mA, 24 VAC PWM), configurable per point.
- Ventilation demand: the HLS 44-CO2 adds a built-in CO2 sensor for demand-controlled ventilation in a single room; the Proxima CU takes an external CO2 input if a zone needs it.
- Actuator type: HLS 44-SE and the Proxima CU both drive 0 to 10 V or PWM (thermal) actuators; a Proxima CU output can also switch to a 6-way valve, 3-point actuator or fan speed function.
- Commissioning: the Proxima CU is set up with the Produal MyTool app, with configuration saved to MyCloud, useful across multi-room projects.
For a straightforward single room on Modbus RTU, choose HLS 44. For BACnet, two rooms per device, or flexible I/O, choose Proxima control units.
FAQ
Common questions
Which HVAC controller supports BACnet?
The Produal Proxima CU, which offers BACnet MS/TP over RS-485 and BACnet IP over Ethernet, as well as Modbus RTU and Modbus TCP. The HLS 44 room controller and CU-LH-MOD variant use Modbus RTU only, so choose the Proxima CU when the BMS specifies BACnet.
Can one control unit handle two rooms?
Yes. The Produal Proxima CU can control two rooms from a single unit over its RS-485 bus, with independently configurable inputs and outputs for each. This reduces panel space and wiring on multi-room floors compared with one controller per room.
Room controller or zone control unit for a fan coil?
An HLS 44 room controller suits a single fan coil, VAV box or radiator circuit on Modbus RTU. A Proxima control unit suits zones needing BACnet, two-room control, or outputs beyond simple heating and cooling, such as a 6-way valve or 3-point actuator.
What sensors connect to a Proxima control unit?
Its six universal inputs accept passive NTC10 or Pt1000 sensors, 0 to 10 VDC transmitter signals, resistive or digital contacts. That flexibility lets one control unit read room temperature, a CO2 transmitter or a window contact without extra input modules.
Which room controller has a built-in CO2 sensor?
The HLS 44-CO2, which adds a CO2 sensor with typical accuracy of plus or minus 40 ppm and 3% of reading to the standard HLS 44 room controller, for demand-controlled ventilation in a single occupied space such as a meeting room.
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