Modern Flue Systems: Safe and Efficient
Current Applications in Flue Gas Technology
Safety, efficiency, comfort, and ecological standards: Heating and flue gas technology is at the intersection of various challenges and trends. Increasing regulatory requirements, such as the EcoDesign Directive (ERP), are also being introduced. To always have the right solution for customers – whether private or commercial – manufacturers and tradespeople need to be not only up-to-date but also offer systems tailored to demand. Here, we present some key trends.
Energy-Efficient Heating Requires Modern Flue Gas Technology
The European Union's EcoDesign Directive now also applies to heating systems. Since September 26, 2015, manufacturers are no longer allowed to bring low-temperature heating devices with a capacity of less than 400 kW onto the market. Instead, energy-efficient condensing boilers are increasingly being used. These devices achieve a high efficiency by reusing the condensation heat from the flue gas to generate heat, resulting in an increased condensate output due to lower flue gas temperatures. Condensing units expel the flue gas under pressure using a fan. Therefore, the flue pipes must not only be designed for pressure but also prevent the escape of flue gas or condensate. Corrosion-resistant flue systems made of stainless steel or polypropylene (PP) are ideal for condensing boilers, as they allow for pressure-tight flue gas solutions.
Retrofitting Often Requires Renovation
Not only do age-related wear and tear on chimneys often necessitate chimney renovation, but when modern heating systems are installed, the existing chimney often needs to be upgraded. This is because outdated chimney designs may lead to condensation problems when modern heating units, which produce low-temperature flue gases, are connected. The cross-section of older chimneys is often too large for the low exhaust temperatures of modern heating systems, which can lead to the chimney’s masonry being severely attacked by condensate, acid, and existing tar residues. This results in unpleasant odors and long-term damage to the building structure.
Chimney renovation typically involves the installation of stainless steel or polypropylene flue pipes from the chimney head. The type of flue system selected depends largely on the type of heating appliance, for example, the air supply of the respective condensing unit. Unlike air-dependent condensing boilers, room-independent units draw combustion air from outside rather than from the room. For existing chimneys, single-wall pipes can be used, which are installed from the chimney head.
Fresh air is supplied via the unused annular gap of the chimney. However, concentric LAS chimneys, such as those offered by Jeremias Flue Systems, are becoming increasingly popular. These systems use the annular gap between the inner and outer pipes for the air supply and are suitable for installation in dirty ducts or external areas. It is essential that the flue system selected is approved for the new heating appliance.
More Than Just Hot Air
Combined heat and power (CHP) systems can be operated with various combustion engines and have a particularly high efficiency – making them a valuable contribution to the energy transition. The principle of combined heat and power (CHP) generates electricity, with the heat produced being used locally, for example, for heating or as process heat in industry. From nano to large-scale CHP systems, the correctly dimensioned flue system is critical. For these applications, particularly single- or double-walled stainless steel systems with metallic conical surface seals are ideal. By eliminating silicone or EPDM seals, more demanding applications with temperatures up to 600°C can be implemented using conical flue systems such as the EW-/DW-KL systems from Jeremias. In any case, flue systems for CHP units should withstand pressure surges up to 5,000 Pa, meeting the highest requirements for temperature and pressure resistance. Modular flue systems are also preferred over welded alternatives, as they are easier and faster to install thanks to specially developed, length-adjustable components, saving both time and costs. Additionally, the low-frequency hum of the systems can sometimes be disturbing, and specifically designed and tuned flue silencers can help mitigate such noise disturbances.
Flue Systems for Decorative Gas Fireplaces
Decorative gas fireplaces are very trendy for good reason: They can be conveniently controlled by timers and used to regulate room temperature. As decorative elements, they create a pleasant ambiance and can visually vary their flame settings. For flue pipes, specially designed concentric systems are recommended, which use the annular gap between the inner and outer pipes for air supply. To prevent any exchange between combustion air and room air, the flue system must be pressure-tight at the outer casing. Ideally, it is a system that passes the blower-door test. It is essential that the selected flue system is certified by the decorative gas fireplace manufacturer, which, for example, applies to Jeremias' TWIN-GAS system in many cases.
Principle of "Sustainability"
When fossil fuels such as oil, coal, or natural gas are burned, carbon compounds are released that were removed from the atmosphere and the carbon cycle millions of years ago. This contributes to the well-known greenhouse effect. Biomass, on the other hand, only releases the amount of greenhouse gases that was absorbed by plants during their natural growth. As a result, the ecological balance is not disturbed. Biomass can be used as a regenerative, natural resource in solid, liquid, or gaseous forms to generate energy (heat, cold, and electricity) or fuel such as biodiesel or vegetable oil. Specifically, various wood types like wood chips, logs, or pellets, liquid biomass such as rapeseed oil and sunflower oil, or fermented gas, such as from manure, are used. For biomass heating appliances such as pellet stoves, biomass boilers, biogas plants, or biomass heating plants, soot-resistant and corrosion-tested flue systems with verification classes V2 and/or V3 are recommended. These verification classes determine the corrosion resistance class according to DIN V 18160-1 and depend on the respective fuel. With the right flue system, such as EW-/DW-SILVER and DW-Mammut from Jeremias, safe and clean operation is always ensured.
Conclusion
Flue systems today do more than simply direct smoke out of the room. They contribute to a comfortable room climate, make heating systems more efficient, and enable both air-dependent and air-independent combustion methods with innovative air supply systems. It’s not just about adhering to current standards; it’s about providing customers with the right solution for their specific needs.