Outer wall chimney, which bears the designation "double-shelled" due to its structure as a double pipe. In contrast to the double-walled chimney, the distance between the inner and outer ring remains free of insulation material and is used for combustion air intake via the chimney mouth. By directing the exhaust gases in the inner pipe past the supply air in the outer tube, the fresh air is preheated and energy is saved. This is referred to as an air-exhaust system, LAS.
The chimney is mainly made of high-quality stainless steel and is routed over the roof on the façade outside the building. It has been developed exclusively for indoor air-independent operation.
In principle, this type of chimney is suitable for all fuels in both low-pressure and overpressure operation. However, due to the rapid cooling of the exhaust gas, overpressure operation is particularly suitable for gas- or oil-powered fireplaces, in which the cool exhaust gas is blown through the chimney with a fan. Chimney systems generally require building authority approval.
Source: bauwion
