Ariston Alteas Series Overview

Ariston Alteas ONE NET and Alteas XP are air-to-water heat pumps (6-16 kW) designed for residential and light commercial heating/cooling and DHW. The two models have different KNX integration paths, and specifying the correct model before designing the integration is essential.

Integration Option 1: NET Module REST API

The Ariston NET module (mandatory for remote access via the Ariston app) exposes a local HTTP/REST API on the home network. An Enertex EibPC or similar logic controller can poll this API and bridge values to KNX group objects. This works for both Alteas ONE NET and Alteas XP, but is limited by the polling rate of the REST API (typically 30-second minimum interval).

Integration Option 2: Modbus RTU on Alteas XP

Modbus RTU (RS485) is available on Alteas XP via the Communication Module (COM module) accessory. RS485 parameters: 19200 baud, 8N1, unit ID 1. Key holding registers: 0 (operating mode, 0=off, 1=heating, 2=cooling, 3=DHW), 1 (flow temperature setpoint, uint16, 0.1 degrees C), 100 (flow temperature actual, int16, 0.1 degrees C), 101 (return temperature, int16, 0.1 degrees C), 102 (outdoor temperature, int16, 0.1 degrees C), 200 (compressor status, 0 or 1), 201 (COP, uint16, 0.01).

KNX/Modbus Gateway Configuration

Use MDT SCN-MIG.01 or Weinzierl 5010 as the RS485/Modbus-to-KNX gateway. Poll flow temperature (register 100) every 30 seconds and map to KNX DPT 9.001. Poll operating mode (register 0) and map to KNX DPT 5.001. To write a flow temperature setpoint from KNX, write to Modbus register 1 — this requires the write-enable jumper on the COM module to be in the enabled position.

SG Ready Integration

Ariston Alteas supports SG Ready via two dry-contact inputs on the terminal block (terminals SG1 and SG2). State table: SG1=0 and SG2=0 means blocked (tariff lockout); SG1=1 and SG2=0 means normal operation; SG1=0 and SG2=1 means recommended on (PV surplus); SG1=1 and SG2=1 means forced on (grid emergency). A KNX binary output module (MDT AKD-0800.01 relay actuator, 2 channels) drives SG1 and SG2. KNX time switch or PV surplus logic controls these output channels.

DHW Boost for Legionella Cycle

Write SG state 3 (both contacts SG1 and SG2 closed) to force DHW heating to the maximum setpoint. This is useful for a weekly legionella thermal disinfection cycle triggered by a KNX weekly timer object.

Work Mode Monitoring

Map Modbus register 0 to a KNX status display: 0=off (grey indicator), 1=heating (red), 2=cooling (blue), 3=DHW (cyan). This gives occupants and building managers a live view of heat pump mode on the KNX touch panel.

Model Selection Pitfall

Alteas ONE uses a proprietary eBUS-like protocol (not standard eBUS) accessible only via the NET module REST API. The Alteas XP has the standard Modbus RTU COM port. Always confirm the exact model ordered before specifying the integration method — the ONE and XP look visually identical in brochures but have fundamentally different local communication interfaces.