Remeha
Quinta Ace cascade boiler plants with eBUS Modbus KNX integration
Remeha (Apeldoorn, Netherlands — founded 1935, part of BDR Thermea Group) produces gas condensing boilers and cascade plants dominant in the Netherlands and Belgium commercial building market. The Gas 220 Ace and Quinta Ace series serve hotels, schools, hospitals, and multi-apartment blocks as cascade plants delivering 115–1150 kW (up to 10-boiler cascade). Remeha uses eBUS as its proprietary boiler communication protocol — integration to KNX requires an eBUS-to-Modbus RTU adapter followed by a Modbus-to-KNX gateway, a two-step conversion that is well-established in the Dutch market.
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How we use Remeha
The Remeha Gas 220 Ace (35–115 kW) and Quinta Ace 115 (cascade module) dominate Dutch commercial heating plant rooms. Both use the eBUS protocol on a 2-wire bus between boiler, controller, and room thermostat. eBUS is a Remeha/Vaillant industry standard — electrically it runs on a 12V DC 2-wire bus, electrically similar to KNX TP but with a completely different data layer. For multi-boiler cascade plants, each Quinta Ace module connects to an eBUS hub, with the lead boiler controller managing sequencing. The eBUS-to-Modbus RTU adapter (available from third-party suppliers including Esbe, or via Remeha dealer network) bridges eBUS data to standard Modbus RTU RS-485. Key Modbus registers from the eBUS adapter: Register 1 (flow temperature setpoint, 0.1°C resolution, read/write), Register 2 (operating status: 0=standby, 1=heating, 2=DHW, 3=fault, read-only), Register 100 (fault code, read-only), Register 200 (gas consumption today, kWh, read-only). A Modbus RTU-to-TCP converter (Moxa NPort 5110, DIN-rail mount) bridges RS-485 to Ethernet, presenting a Modbus TCP server for the KNX gateway. The Intesis IN701KNX Modbus TCP-to-KNX gateway then maps registers to ETS6 group addresses. For Quinta Ace cascade plants with multiple boiler modules, each boiler module has its own eBUS address (module address 1–10 configurable on the boiler PCB). The lead boiler controller aggregates cascade operating data (burner count, total heat output, cascade status) on its eBUS address. For KNX integration of cascade plants, the standard approach is to integrate the lead boiler's eBUS address — which exposes aggregate plant status — rather than individual module addresses. This gives KNX a single point of control for cascade setpoint and a single fault alarm group address covering the whole plant. Remeha Control Online is a cloud-based building energy management and monitoring platform connected via the Remeha eVita internet gateway. While it does not provide a direct KNX interface, Remeha Control Online exposes an API (REST/JSON) for energy reporting that can be consumed by a Home Assistant integration and bridged to KNX group addresses for energy dashboard display. This is supplementary to the eBUS-Modbus-KNX direct integration path and used for long-term energy reporting rather than real-time control.
Remeha boilers use eBUS proprietary protocol. The Remeha eBUS-Modbus RTU adapter bridges eBUS to Modbus RTU, then Modbus RTU-to-TCP converter (Moxa NPort) provides Modbus TCP for KNX gateways. Key registers: flow setpoint (Reg 1), operating status (Reg 2), fault code (Reg 100), gas consumption (Reg 200). For Quinta Ace cascade plants, each boiler module exposes its own eBUS address — the lead boiler aggregates cascade status for KNX monitoring.
Used in these project types
Remeha products
Key components we install
Gas 220 Ace
35–115 kW wall-hung gas condensing boiler. eBUS protocol for external control and monitoring. Standard for Dutch and Belgian commercial installations. KNX integration via eBUS-Modbus adapter + Moxa NPort + Intesis IN701KNX. Can be connected in cascade up to 10 units via eBUS hub for 350–1150 kW plant.
Quinta Ace 115
115 kW modular cascade boiler for high-output commercial plants. Each module adds 115 kW; cascade controller manages sequencing and load balancing. Lead boiler exposes aggregate plant data on eBUS for KNX integration. Common in Dutch hospitals, schools, and hotel boiler plants requiring 230–1150 kW.
Elga Heat Pump
Remeha air/water heat pump for hybrid heating alongside gas cascade. Integrates with Remeha cascade controls via eBUS. KNX integration follows same eBUS-Modbus-KNX path as gas boilers. Suitable for hybrid plant replacing one boiler cascade module for heat pump priority operation.
eBUS-Modbus
eBUS to Modbus RTU RS-485 bridge adapter for Remeha boiler integration. Connects to Remeha eBUS 2-wire bus (alongside room thermostat). Presents Modbus RTU slave (RS-485, 9600 baud, 8N1). Pair with Moxa NPort 5110 for Modbus TCP conversion. Essential hardware for any Remeha KNX integration project.
iSense Pro
Remeha native eBUS room thermostat with weekly programming and auto-learning. eBUS connected directly to boiler — no KNX interface. Used in zones without KNX room control, or as backup thermostat in KNX-integrated systems where KNX control is primary but local override is required.
Remeha FAQ
What is eBUS and why does Remeha KNX integration need an adapter?
eBUS is a proprietary 2-wire bus protocol developed jointly by Remeha, Vaillant, and other European boiler manufacturers. It uses 12V DC signalling on a 2-wire bus and carries boiler operating data, thermostat commands, and diagnostic information. While it shares some electrical similarities with KNX TP, the data protocol is completely different and incompatible. KNX integration requires a protocol converter: first an eBUS-to-Modbus RTU adapter (translates eBUS frames to standard Modbus registers), then a Modbus RTU-to-TCP converter (Moxa NPort), then an Intesis IN701KNX Modbus TCP-to-KNX gateway. This two-step conversion is the established method in the Dutch commercial building market.
Can KNX control the Remeha cascade boiler sequencing?
KNX can set the cascade plant flow setpoint (Reg 1 via eBUS-Modbus adapter → Intesis IN701KNX → KNX GA 8/0/0, DPT 9.001) and read cascade operating status (Reg 2 from lead boiler). However, boiler sequencing — which modules fire in which order — is managed by the Remeha cascade controller internally. KNX does not override the sequencing algorithm. KNX can implement lead-lag switching at a plant level: if a second cascade plant (boiler room B) exists, KNX can enable/disable each plant's setpoint based on outdoor temperature and total load, acting as a high-level supervisor while each cascade controller manages its own sequencing.
How is Remeha boiler gas consumption monitored via KNX?
The eBUS-Modbus adapter exposes cumulative gas consumption (Register 200, kWh, read-only) from the Remeha boiler's internal gas meter calculation. The Intesis IN701KNX gateway maps this to a KNX group address (DPT 13.013, 4-byte signed int). For daily or monthly reporting, a KNX logic module (e.g. MDT Logic Controller or Home Assistant KNX integration) reads the cumulative counter at midnight, calculates daily delta, and stores it for energy reporting. For multi-boiler cascade plants, each boiler module's gas consumption register must be read individually and summed — the lead boiler does not aggregate consumption across all modules.
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