Acid-proof, insulated washout allows access to the chimney system and pollution control.

Insulated chimneys are used for the construction of free-standing chimneys to remove flue gas from heating appliances fired with gas or fuel oil, working under vacuum. The chimney made in this technology is a stand-alone structure, not requiring the use of conventional ceramic material. 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 in the form of condensate is drained through a bowl at the bottom of the chimney.

The inner chimney jacket in double-walled is made of acid-resistant chromium-nickel sheets in grade 1.4404 according to DIN 17441, thickness 0.5 to 0.8 [mm], outer jacket made of acid-resistant steel 1.4301, thickness 0.5 - 0.6 [mm], insulation thermal has a thickness of 35 to 50 [mm].