Trane
RTAA/RTWA chillers with BACnet/IP for KNX large commercial building integration
Trane (Trane Technologies, La Crosse WI) manufactures large commercial HVAC — RTAA/RTWA chillers (60–750 kW) and the Tracer SC+ BMS. BACnet/IP integration bridges Trane systems to KNX for buildings where US-designed mechanical meets European automation.
Role in our panels
How we use Trane
Trane RTAA (air-cooled) and RTWA (water-cooled) chillers run a BACnet/IP stack natively in the chiller controls panel — no additional hardware is required on the chiller side for BACnet communication. The RTAA 130 exposes approximately 150 BACnet objects including Analog Values (chilled water supply setpoint, leaving water temperature, entering water temperature, compressor amps, total kW), Binary Values (chiller run status, fault active, alarm active), and Multi-State Values (chiller operating mode). The Tracer AdaptiView control panel provides a BACnet/IP device at the chiller, accessible from the building network over standard Ethernet. The LOYTEC LGATE-952 BACnet-to-KNX gateway acts as BACnet client and KNX server simultaneously. Configuration workflow: connect LGATE-952 to building Ethernet; in LOYTEC L-STUDIO configuration software, add the Trane chiller as a BACnet device (enter chiller IP and Device ID from Tracer AdaptiView display); browse the BACnet object list and select required objects; map each to a KNX group address with appropriate DPT. Key mappings: CHWST Setpoint AV → GA (DPT 9.001, °C), Leaving Water Temp AV → GA (DPT 9.001), Chiller Status BV → GA (DPT 1.001), Fault Active BV → GA (DPT 1.005). LOYTEC LGATE supports scripting for setpoint calculations. Weather-compensated chilled water setpoint control from KNX is the primary use case in large office and hotel buildings. A KNX outdoor temperature sensor GA feeds a KNX logic function block (LOYTEC LVIS-ME3 or Gira HomeServer script) that calculates the optimal chilled water setpoint: at outdoor 25°C → 7°C chilled water; at outdoor 35°C → 6°C chilled water; intermediate temperatures interpolated linearly. The calculated setpoint GA maps via LGATE-952 to the Trane CHWST Setpoint BACnet AV. Setpoint adjustment in response to KNX occupancy (occupied/unoccupied scenes) enables setpoint reset during off-peak hours. Tracer SC+ (Trane's BMS controller) provides an OPC UA server interface as an alternative integration path for projects using KNX Virtual or Weinzierl KNX IP Interface. The Tracer SC+ OPC UA bridge exposes the full Trane building model including AHU supply air temperature, VAV box positions, and chiller staging status. For buildings with existing Tracer SC+ BMS, PanelCraft recommends the OPC UA bridge approach over direct LGATE BACnet/IP integration to avoid duplicate polling of the same chiller BACnet device.
Trane RTAA/RTWA chillers run a BACnet/IP stack natively (no gateway needed on chiller side). LOYTEC LGATE-952 acts as BACnet client and KNX server. Configuration: LGATE BACnet device table → add Trane chiller IP, browse objects, select Analog Value 'CHWST Setpoint', Analog Value 'Leaving Water Temp', Binary Value 'Chiller Status', Binary Value 'Fault Active'. Map to KNX GAs: setpoint DPT 9.001, supply temp DPT 9.001, on/off DPT 1.001, fault DPT 1.005. Write setpoint from KNX outdoor temperature sensor for weather-compensated chilled water control.
Used in these project types
Trane products
Key components we install
RTAA 130
130 kW air-cooled scroll chiller with Tracer AdaptiView control panel and native BACnet/IP. Four scroll compressors with unloading capability for part-load efficiency. Variable speed condenser fans for low ambient operation. ESEER rating up to 4.5. BACnet device ID configurable via Tracer AdaptiView display — required for LOYTEC LGATE-952 BACnet device table configuration. Used in medium commercial buildings (5,000–15,000 m2), hotels, and office buildings where cooling capacity is 100–200 kW.
RTWA 150
150 kW water-cooled centrifugal/scroll chiller for buildings with cooling tower. Higher efficiency than air-cooled RTAA at same capacity (ESEER up to 6.1). BACnet/IP native — same LOYTEC LGATE-952 integration as RTAA. Requires cooling tower, condenser water pump, and associated panel wiring. Used in data centres, hospitals, and large hotels where cooling tower infrastructure is available and energy efficiency is the primary specification criterion.
CenTraVac
Large capacity centrifugal chiller 500+ kW for district cooling, large hospitals, and airports. Variable speed drive on compressor for exceptional part-load efficiency (IPLV up to 7.0 kW/kW). BACnet/IP native with extensive object list including compressor speed, refrigerant pressures, and motor current. LOYTEC LGATE-952 integration maps key energy and status objects to KNX for building-level energy management. Requires specialist Trane commissioning — PanelCraft coordinates panel integration with Trane commissioning team.
Tracer SC+
Trane building management system controller with OPC UA server, BACnet/IP server, and Modbus RTU capability. Manages chiller plant sequencing, AHU control, and VAV box coordination. OPC UA server provides alternative KNX integration path for projects using KNX Virtual or Weinzierl KNX IP Interface — avoids direct BACnet polling of chiller. Tracer SC+ floor plan visualisation shows live HVAC data. In buildings with Tracer SC+, PanelCraft recommends Tracer SC+ OPC UA as primary KNX integration approach rather than LGATE direct BACnet.
CAV AHU
Constant volume air handling unit with heating/cooling coils, heat recovery, and Trane UC400 unit controller. UC400 has BACnet/IP interface for Tracer SC+ supervision. For standalone KNX integration (without Tracer SC+): LOYTEC LGATE-952 maps AHU supply air temp, return air temp, damper position, and heating/cooling valve position BACnet objects to KNX GAs. KNX writes supply air setpoint to AHU via LGATE for BMS setpoint reset from KNX occupancy schedule.
Trane FAQ
Does Trane support KNX natively?
No — Trane chillers and AHUs do not have native KNX interfaces. Integration uses two approaches: (1) BACnet/IP gateway — LOYTEC LGATE-952 or Intesis IN701KNX acts as BACnet/IP client connecting directly to the chiller's native BACnet stack, mapping selected objects to KNX group addresses; (2) Tracer SC+ OPC UA bridge — for buildings with the Tracer SC+ BMS, an OPC UA to KNX bridge (e.g. via KNX Virtual) provides a higher-level integration that includes Tracer's plant sequencing and demand logic. PanelCraft recommends LGATE BACnet/IP for buildings without Tracer SC+, and the OPC UA approach for buildings with Tracer SC+ already commissioned.
Which Trane chiller BACnet objects should map to KNX?
For standard KNX energy management integration, the key Trane RTAA/RTWA BACnet objects to map are: Analog Value 'CHWST Setpoint' (chilled water supply temperature setpoint — writable from KNX), Analog Value 'Leaving Water Temp' (actual supply temp — readable), Analog Value 'Total Unit kW' (electrical demand — for energy metering, DPT 13.010), Binary Value 'Chiller Run Status' (DPT 1.001), Binary Value 'Fault Active' (DPT 1.005). For weather-compensated setpoint control: map outdoor temperature KNX GA to a calculated setpoint GA, then write to CHWST Setpoint via LOYTEC LGATE scripting.
Can Trane chillers integrate with BREEAM energy sub-metering via KNX?
Yes — the Trane RTAA/RTWA BACnet 'Total Unit kW' Analog Value provides real-time electrical demand, and the 'Total Unit kWh' Analog Value provides cumulative energy. Via LOYTEC LGATE-952, these map to KNX DPT 13.010 (demand, W) and DPT 13.013 (energy, Wh) group addresses. The KNX energy data integrates with LOYTEC LVIS-ME3 M&T (metering and targeting) logging or Gira HomeServer energy reports for BREEAM Ene 02 sub-metering compliance. PanelCraft provides BREEAM Ene 02 panel documentation as part of the commissioning package.
Need a panel with Trane components?
We select, procure, assemble and certify. Free initial consultation.
Request consultation →