This Vaillant Air and flue Extension kit allows you to increase the length of a standard Vaillant flue kit by 470 mm. It is compatible with all new Ecotec boilers. This extension from Vaillant is ideal for use with compatible flues. This Vaillant 80/125 flue extension can be used between flue elbows, vertical adaptor and vertical terminal to extend the length of the flue system by up to 470mm. Its suitable for use in conjunction with Vaillant EcoTEC commercial boiler models.