Carrier AquaForce 30XA BACnet/IP interface

The Carrier AquaForce 30XA series chiller communicates via BACnet/IP natively through its i-Vu Open controller. Enable BACnet/IP in the i-Vu controller web interface: navigate to Device Setup → BACnet/IP, assign a unique BACnet Device ID (range 1–4194302, recommended: 4001 for chillers), set UDP port 47808, and enable the BACnet service. The controller joins the local IP subnet and responds to BACnet Who-Is broadcasts. Confirm connectivity with a BACnet explorer tool (Yabe or BACnet Discovery Tool): the chiller should appear with its Device ID and expose its object list.

Key BACnet objects available on the 30XA: Analog Value 'Chilled Water Setpoint' (AV-1, read/write, range 5.0–20.0°C), Analog Value 'Supply Temperature' (AV-2, read-only, live supply water temperature), Binary Value 'Chiller On/Off Status' (BV-1, read-only, 1=running), Binary Value 'Fault Active' (BV-2, read-only, 1=fault present). Additional objects include condenser entering water temperature (AV-3), compressor load percentage (AV-4), and cumulative energy (AV-10, kWh).

LOYTEC LGATE-952 BACnet-to-KNX gateway configuration

The LOYTEC LGATE-952 is a hardware gateway that translates BACnet/IP objects to KNX TP group writes. Connect the LGATE-952 to the IP network (same subnet as the chiller) and to the KNX TP bus. Configuration is done via LOYTEC LVIS-3 software. In LVIS-3: add a BACnet/IP device using the chiller's IP and Device ID. Right-click → 'Scan Objects' to import the full object list. Then map each BACnet object to a KNX datapoint:

AV-1 Chilled Water Setpoint → KNX DPT 9.001 (2-byte float, °C) → GA 9/1/0. Configure as bidirectional (read and write) so KNX can both read the current setpoint and write a new value. AV-2 Supply Temperature → KNX DPT 9.001 → GA 9/1/1 (read-only, send-on-change 0.5°C). BV-1 Chiller Status → KNX DPT 1.001 → GA 9/1/2 (read-only, send-on-change). BV-2 Fault Active → KNX DPT 1.005 (alarm DPT) → GA 9/1/3 (read-only, send immediately on change). AV-10 Energy → KNX DPT 13.013 (4-byte signed long, Wh) → GA 9/1/4 (read-only, cyclic send every 15 minutes).

Weather-compensated chilled water setpoint

A KNX outdoor temperature sensor (e.g., Theben SENS 9070 A) on GA 0/0/0 (DPT 9.001) feeds a KNX logic function implementing weather compensation for the chilled water setpoint. Setpoint curve: at 25°C outdoor temperature → chilled water setpoint = 7°C; at 18°C outdoor → setpoint = 12°C. Linear interpolation: setpoint = 7 + ((25 − T_outdoor) / 7) × (12 − 7). This curve is implemented in an IP-Symcon script or ABB CL/KNX logic module, with the result written to GA 9/1/0.

The energy benefit is significant: each 1°C increase in chilled water setpoint reduces compressor energy consumption by approximately 3–4% due to improved coefficient of performance (COP). Raising from 7°C to 12°C during mild weather (saving 5°C) delivers 15–20% compressor energy reduction. For a 500 kW chiller running 2000 hours annually at partial load, this represents approximately 50,000 kWh/year reduction.

Alternative bridge: Carrier i-Vu OPC-UA to KNX Virtual

Where a dedicated BACnet/KNX gateway is not justified, the Carrier i-Vu BMS includes an OPC-UA server (enabled in i-Vu System Setup → OPC-UA Server, port 4840). KNX Virtual (Weinzierl KNX IP Interface 731 or similar) running on a server can act as a software KNX interface. A Python script using asyncua (OPC-UA client) and xknx (KNX library) reads i-Vu OPC-UA nodes and writes to KNX group addresses via the IP interface. This approach requires a continuously running server but avoids gateway hardware cost.

BREEAM energy metering and commissioning

For BREEAM Ene 01/02 compliance, the AV-10 cumulative energy BACnet object is mapped to KNX GA 9/1/4 (DPT 13.013). The ARISTO BewO energy dashboard subscribes to this GA and logs 15-minute interval energy data, generating the sub-metering report required by BREEAM assessors.

Commissioning test: in ETS6, open Group Monitor and write value 9.5 (°C) to GA 9/1/0 (Chilled Water Setpoint). On the chiller's Carrier controller display, navigate to Operating Parameters → Chilled Water Setpoint and confirm the displayed value changes to 9.5°C within 30 seconds. Then read GA 9/1/2 in Group Monitor and verify it reflects the actual chiller run status. Log fault test: temporarily trigger a test fault via the chiller service menu and verify GA 9/1/3 changes from 0 to 1 in Group Monitor within one BACnet poll cycle (default 10 seconds on LGATE-952).