Elta STDL250-1EC-R Twinflow Centrifugal Box Fan Single Phase EC - 250mm (rectangular spigots)

The Elta STDL250-1EC-R is a Twinflow duty/standby centrifugal box fan for 250mm duct systems, with rectangular spigots sized 254 x 254mm. 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 1210 m³/h free air, about 1066 m³/h at 100 Pa, and still delivers 392 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 1210 m³/h Speed Controllable What it is best used forDuty/standby extract on 250mm ducting for larger toilet blocks, school and college washroom cores, library and classroom extract, office floors and hotel risers. It gives 1210 m³/h free air, about 1066 m³/h at 100 Pa and still 392 m³/h at 500 Pa, so it copes with filters, silencers and longer runs.Being a twin unit in a 40 kg acoustically lined case, it needs more ceiling void than a single fan. Where a short outage is acceptable, a single fan is the smaller and cheaper choice. Not for corrosive, explosive or above +60°C air.Why choose this over alternativesThe point of a twin fan is resilience. A single fan such as the Elta SSDL250-1EC-R Singleflow moves more air in the same duct size (1307 m³/h free air against 1210 m³/h here, and 428 m³/h at 500 Pa against 392 m³/h), but when its motor fails the extract stops until someone replaces it. The STDL250-1EC-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 fan means