The acid-proof base screwed on four pins protects the chimney against atmospheric precipitation as well as facilitates the installation of chimney caps such as e.g. a fireman.

Single-wall chimney liners are made of acid-resistant chromium-nickel steel sheets of 1.4404 grade according to DIN 17441 with a thickness of 0.5 to 0.8 [mm]. They are mainly used to evacuate flue gases from heating appliances using gas or heating oil, operating under vacuum. Such chimneys are resistant to the corrosive effects of acid condensate formed during the combustion process. Water vapor condenses on the cool internal walls of the chimney and is discharged in the form of condensate through a condensate pan at the bottom of the chimney. Condensation may occur during the start-up or cyclical operation of the boiler.