Suitable for the Viessmann residential gas boiler range (Vitodens 100-W & Vitodens 111-W). The flue makes it easy to get around obstructions, and are quick and easy to install. The Vitodens Horizontal Flue Kit consists of: 87° elbow, 500mm pipe and an external outlet. NOTE: Flue system is dependent on boiler output, flue bends and fittings, straight lengths and flue routing.