Flue system
The flue system begins at the end of the boiler or flue gas heat exchanger and has the task of safely discharging the flue gases produced during combustion into the environment. This includes the flue gas lines inside and outside the boiler room, the chimney and any additional fixtures such as expansion fittings, silencers or flue gas flaps.
All components of a combustion system, starting with the burner and its associated fan, through to the boiler, flue gas heat exchanger, flue gas lines, silencer and chimney, must be carefully coordinated. Only then can flawless operation be guaranteed in all operating conditions and over the long term. A lack of coordination or incorrect execution of individual components leads to vibrations, noise, increased emissions or unstable combustion in the overall system.
Flue gas systems must be designed in accordance with the national and local regulations as well as the applicable standards.
General requirements for flue systems in and on buildings are specified in DIN EN 1443.
The design of the flue systems must comply with local building regulations and DIN V 18160.
For free-standing chimneys, the DIN 1056, DIN 4133 and DIN EN 13084-1 standards are applicable in addition to the building laws.
Specifications for fluid dynamics design can be found in standards DIN EN 13384 for flue systems in and on buildings and DIN EN 13084-1 for free-standing chimneys.
Flue gas ducts must be made of non-combustible construction materials and be resistant to the effects of flue gas and heat. The material of the entire flue system for hot water boilers must be suitable for temperatures up to 350 °C.
In the case of a heat recovery boiler for utilising waste heat from flue gases from a CHP system or a gas turbine, or if the boiler is equipped with a fourth pass, the flue system must be suitable for the highest temperature of the entire system.
Additional country-specific requirements are often imposed on the design of the flue system and the height of the chimney.