Eurapo Sigma 522, a fan coil from the EST inverter range: horizontal ceiling unit, frontal air discharge, bottom air intake. As ordered it carries a 3-row water coil; an EC brushless motor with built-in inverter; no regulating valve — the unit is supplied for an external valve or for constant-flow operation; the AS air sensor (NTC 10 kΩ at 25 °C) on the air intake; an OPower BMS card (Modbus RTU over RS-485) for integration into a building management system; the KPPH back panel for installations where the rear of the unit is in view; water connections on the right-hand side (DX, the factory standard; SX is the left-hand alternative). Rated performance for this configuration: cooling capacity 5.81 kW, heating capacity 6.53 kW, sound power level 29–52 dB(A), water connections 1/2 x 1/2". Maximum operating pressure is 16 bar without valves fitted. Full type designation ESTSH/AF 522-3R+AS+ORBV.10+KPPH+DX. Supplied under manufacturer part number ESTSH/AF522-3R+OPTV20W, HS code 8415.90, country of origin Italy.