Elta STDL125-1EC-R Twinflow Centrifugal Box Fan Single Phase EC - 125mm (rectangular spigots)

The Elta STDL125-1EC-R is a Twinflow duty/standby centrifugal box fan for 125mm duct systems, with rectangular spigots sized 148 x 198mm. Two backward curved fans sit side by side in one acoustically lined case: one runs, the other waits on standby. At full speed it moves up to 418 m³/h free air, about 371 m³/h at 100 Pa, and still delivers 137 m³/h against 500 Pa.Each fan has an IP44 EC external rotor motor (220 to 240V single phase, 50/60Hz) with sealed for life bearings, and the case is 1.2mm galvanised mild steel. An auto changeover panel (149-ACO1/EDV) is fitted as standard, switching to the standby fan if the duty fan fails and sharing run hours between the two. Speed is set by the built in commissioning potentiometer or a 0-10V signal, and Elta give a 12 month (1 year) manufacturer warranty. 1 Phase EC Motor Up to 418 m³/h Speed Controllable What it is best used forSmall washroom and toilet extract where the fan must keep running: hotel en suite risers, school and college toilet blocks with two or three cubicles, accessible WCs, cleaners' stores and small internal offices with no openable window. At 418 m³/h free air, or about 371 m³/h against 100 Pa of ductwork, it suits short to medium 125mm duct runs.At this size the airflow drops steeply as resistance rises: by 300 Pa it is down to about 263 m³/h. If the duct run is long, has several bends or ends in a louvre, look at the 150mm model or larger.Why choose this over alternativesThe point of a twin fan is resilience. A single fan such as the Elta SSDL125-1EC-R Singleflow moves more air in the same duct size (601 m³/h free air against 418 m³/h here, and 302 m³/h at 500 Pa against 137 m³/h), but when its motor fails the extract stops until someone replaces it. The STDL125-1EC-R keeps running on its standby fan, the panel gives normally open fail and run contacts for a BMS or alarm, and the duty share means neither motor does all the hours. Choose it for windowless toilets, risers and any system where a dead fa