Before chimney and flue gas condenser an exhaust fan is installed, which creates negative pressure throughout the flue gas passes of the heating system. A control device ensures that the exhaust fan in interaction with the combustion air fans keeps a preset negative pressure in the combustion chamber.
The exhaust fan then forces the flue gas into the flue gas condenser and the chimney. Individual chimney heights should be determined on the basis of the environmental requirements.
For small plants with flue gas condenser, the chimney should be designed so as to avoid corrosion damage, i.e., glass fibre or rust-proof materials should be used.
Soot emission from chimneys of systems with flue gas condensation causes problems at some heating plants.
The smoke is saturated with water vapour. It also contains dissolved salts and perhaps impurities from the flue gas condensate, which may be deposited in
the chimney.
Soot emission occurs when the deposits in the chimney loosen and are passed along with the flue gas flow.
Efficient mist eliminators, low velocities in the chimney, and perhaps the installation of a wash-down system in the chimney can be recommended so as to eliminate the problem.