The Intergas HRE & EcoRF Boiler Range utilise a concentric flue arrangement consisting of a 60mm diameter inner flue (exhaust) and a 100mm diameter outer (air inlet) duct as standard. The system can be installed in a horizontal or vertical configuration up to a total length of 10 metres from the boiler to its termination point e.g. suitable outside wall/roof area. Should there be a requirement for bends to be installed along the length of the flue this will impact on the permitted distance that the flue can be run. Your Gas Safe Registered Engineer will check this prior to installation and advise on the suitability of this system.