An exterior wall chimney sets a design accent on the façade and is equally suitable for new construction and for retrofitting to existing buildings. It is space-saving and, due to its low weight, can be easily erected without a foundation.
In principle, there are systems for every type of fuel. The predominant building material stainless steel in high quality guarantees a long service life for the system exposed to the weather.
Outdoor chimney systems are modular systems: The chimney is assembled from a wide range of individual parts and accessories, usually by a specialist company. They also help with the choice of chimney system in relation to the chosen fireplace and, if necessary, also carry out the cross-section calculations according to DIN EN 13384.
In principle, the planner should carefully check the building authority approval or CE certification of the system in question in order to ensure compatibility between fireplace and chimney.
With regard to future developments in the fuel market, but also for technical reasons, it can make sense to maintain a certain degree of flexibility: In the case of systems that are equally approved for all exhaust gas temperatures and operating modes, it is easy to change the type of fireplace or fuel in later years. However, these systems are usually also significantly more expensive.
Approval: In principle, the construction of an external exhaust system is an undertaking that requires approval or notification. Before an exhaust system is installed , it must be checked in each individual case whether the respective state building code requires approval for the application in question. In some federal states, systems in small dimensions inside or outside a building do not require a permit or a procedure at all. In any case, it is important to consult with the local district chimney sweep, who represents the lower building authority and must accept the system after completion of the work and before commissioning.
Regulations: For general requirements in planning, such as the minimum distances to combustible components or the location of the chimney mouth above the roof, the Combustion Ordinance FeuV of the respective federal state and the Federal Immission Control Ordinance BImSchV must generally be observed.
Since external chimneys are in most cases metallic system systems, the systems are generally developed and manufactured in accordance with DIN EN 1856 or DIN EN 14989 .
On site, the national design standard DIN V 18160-1 is particularly important for the planner when designing the exhaust system . Despite its status as a pre-standard, it forms the basis for the planning, execution and acceptance of an exhaust system in Germany, together with Supplements 1-3 and DIN 18160-60 .
Fire protection/distance to combustible components: Flue gas systems and their individual parts are generally subject to a marking obligation, in which the fire resistance class and the respective minimum distance to combustible parts to be observed must be shown. See encyclopedia articles ►Flue system, marking according to DIN V 18160-1 and ►Flue system, soot fire resistance class according to DIN V 18160-1.
For external flue gas systems without a shaft jacket, the MFeuV prescribes separate safety distances to combustible components:
For detailed information regarding distances to combustible components, see lexicon article ►Exhaust system, distances to combustible components according to MFeuV.
Stability: Metal chimneys attached to the outside of the wall are usually attached to the wall via a wall bracket or placed on the floor with a plinth element (e.g. made of concrete). In principle, the stability of exhaust systems must be proven in accordance with DIN V 18160-1.
However, a foundation is usually not necessary due to the light weight of the system.
According to DIN V 18160-1, the wall-mounted system is considered a component that is not susceptible to vibration if the following conditions are met:
If these specifications are met, only the anchoring forces on the façade need to be verified. Additional proof of stability is not required if it is a system exhaust system that has provided proof of stability as part of its approval. Information on connection forces for brackets / wall brackets or other product-dependent static requirements can be found in the product brochure or requested from the manufacturer.
If the maximum free height of 3 m cannot be maintained, e.g. if the chimney is on the eaves side, rope bracing must be used if necessary. See also encyclopedia article ► Chimney mouth, location above roof according to BImSchV
Coordination of the system to the fireplace or the fuel: The properties of the chimney system must be adapted to the respective fireplace:
Combustion air supply: If the combustion air for a fireplace is to be supplied via the external chimney system (room-air-independent operation), there are basically two variants:
Material: The materials of external chimneys must withstand high and rapid temperature fluctuations and a wide variety of weather influences. The predominant material for external wall chimneys is therefore stainless steel. Almost all systems on the market consist of it, at least in part. It is important to ensure that the pipes are made of so-called austenitic stainless steels (designation V2A or V4A), which are more resistant to corrosion and withstand high temperatures compared to ferritic stainless steels.
Inner tubes made of austenitic stainless steel are usually made of metal of material numbers 1.4517 or 1.4404. In addition, ceramic materials are also common, which better shield exhaust noise. For low exhaust gas temperatures, plastic pipes without soot fire resistance can also be used in oil and gas burners, but these are rather rare in external exhaust systems. In this case, one no longer speaks of a chimney, but of an exhaust pipe.
Austenitic steel of material number 1.4301 is mainly used for outer tubes. However, copper-plated tubes or tubes made of solid copper are also available on the market.
In addition, there are a wide range of design options with regard to the outer surface, as many manufacturers offer the metal surfaces in either glossy or matt finish. Powder coatings and paintwork in RAL tones are also possible.
Cleaning openings: Cleaning openings are mandatory in exhaust pipes to allow sweeping and pipe inspections. For safe cleaning, these should be 40 to 140 cm above a standing surface. In addition, a minimum distance of 40 cm (without radiation protection) or 20 cm (with radiation protection) must be maintained between the cleaning opening and flammable components.
It is always advisable to coordinate the number and location of the openings with the local chimney sweep/chimney sweep in good time and individually.
Roof penetration: Roof penetrations are often unavoidable, e.g. in the case of a large roof overhang. In this case, the position of the chimney in the new building should be adjusted to the rafter position at an early stage in order to be able to maintain minimum distances to combustible components as easily as possible. System-specific rafter brackets serve as horizontal brackets in the roof truss area, which at the same time ensure the necessary stability and compliance with the minimum distances to the rafters.
These systems also take care of the passage through the roof cladding. As a rule, these are roof penetration elements that are installed in the chimney system at the relevant height or placed over the chimney and sealed. They are available for different roof pitches, but also for flat roofs.
Due to their flexibility, attached lead aprons enable good adaptation to existing roof coverings or other roof surfaces.
Roof
penetration by means of the
chimney duct element chimney head/mouth: The location of the chimney mouth above the roof is regulated by law in order to exclude hazards from harmful and hot exhaust emissions. See encyclopedia article ►Chimney mouth, location above roof according to BImSchV.
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Installation on site: The chimney is delivered to the construction site in individual parts and is usually installed by a local specialist company. The chimney system manufacturer provides relocation instructions for this purpose, in which the assembly and assembly are described in detail. Installation by a specialist company, e.g. a stove construction or chimney construction company, ensures that there are no errors in the execution due to the large number of individual parts and the care required with regard to safety-relevant requirements.
Installation in full assembly: If the chimney system is delivered to the construction site floor by floor and lifted to the façade by crane, all the individual parts are fully assembled and already included in the elements. On site, the elements only have to be connected to each other. This construction variant saves time, but is rather rare for outdoor chimneys in small dimensions.
Damaged parts: Pipe elements that are dented and dented at the edge are considered damaged and must not be used for assembly, as the tightness of the pipe connection is no longer guaranteed. Careful handling during delivery and assembly is therefore important. It is also advisable to pay attention to a sufficiently stable material thickness of at least 0.4 mm when buying.
Acceptance by the chimney sweep / chimney sweep: The local chimney sweep / chimney sweep plays a central role in the planning and execution of flue gas systems. After completion of the work and before commissioning, the plant will be inspected and approved by him in Germany in accordance with building regulations. The plant concept should therefore be discussed with him before the start of the work. A construction inspection during the execution can also be useful.
DIN EN 1443, Flue gas systems - General requirements
DIN EN 1856-1, Flue gas systems - Requirements for metal exhaust systems - Part 1: Components for system exhaust systems
DIN EN 1856-2, Flue gas systems - Requirements for metal exhaust systems - Part 2: Metal inner pipes and connectors
DIN EN 1859, Flue gas systems - Metal flue gas systems - Test methods
DIN EN 13384-1, Flue gas systems - Heat and flow calculation methods - Part 1: Flue gas systems with a fireplace
DIN EN 13384-2, Flue gas systems - Thermal and flow calculation methods - Part 2: Flue gas systems with several fireplaces
DIN EN 14989-1, Flue gas systems - Requirements and test methods for metal flue gas systems and material-independent air ducts for air-independent installations - Part 1: Vertically arranged air/exhaust gas attachments for flue gas systems with gas appliances of type C6
DIN EN 14989-2, Flue gas systems - Requirements and test methods for metal flue gas systems and material-independent air ducts for air-independent systems - Part 2: Flue gas and air ducts for air-independent fireplaces;
DIN EN 15287-1, Flue gas systems - Planning, installation and acceptance of flue gas systems - Part 1: Flue gas systems for room air-dependent fireplaces
DIN EN 15287-2, Flue gas systems - Planning, installation and acceptance of flue gas systems - Part 2: Flue gas systems for air-independent fireplaces
DIN V 18160-1, Flue gas systems - Part 1: Planning and execution
DIN V 18160-1 Supplement 1, exhaust systems — Part 1: Design and execution; National Supplement to the Application of Metal Flue Systems according to DIN EN 1856-1, of Inner Pipes and Connectors according to DIN EN 1856-2, the Permissibility of Materials and Corrosion Resistance Classes
DIN V 18160-1 Supplement 2, Flue Systems — Part 1: Planning and Execution; National supplement to the application of ceramic inner shells according to DIN EN 1457, assignment of the marking classes for mounting exhaust systems
DIN V 18160-1 Supplement 3, Flue gas systems - Part 1: Planning and execution; Supplement 3: National Supplement to the Application of System Flue Systems with Plastic Inner Pipes according to DIN EN 14471
DIN 18160-60, Flue Systems, Part 60: Evidence for the Fire Behaviour of Flue Gas Systems and Components of Flue Systems — Terms, Requirements and Tests
BImSchV, Federal Immission Control Ordinance
EnEV, Energy Saving Ordinance
►MFeuV, Model Combustion Ordinance
►Federal Association of Chimney Sweeps
Source: bauwion
