Depending on the configuration of your home, if the suction cup is not suitable, the evacuation of the combustion gases will be via a flexible tube with a diameter of 80 mm, a tube inserted into the chimney of the building (diagram attached). Important to know: If you replace an old atmospheric boiler connected to a chimney, with a condensing boiler, you must surely pipe the chimney. Price of C93 tubing: 10 meters of PP tubing, including cap and other accessories, extra €800 including 6% VAT.