Vented for supplying several draw-off points in commercial, industrial and domestic situations. Existing connectors for: Cold water and DHW, and in the upper area (except SB 650/3 AC), for thermometer, DHW circulation and threaded heater (BGC). Internal steel cylinder with special enamel coating and protective anode. The flanged apertures (delivered with fitted protective caps) are equipped on site subject to requirements, i.e. either with immersion heaters (FCR), heat exchangers (WTW, WTFS) or dummy flanges (B).