Jeremias® Exhaust Systems

    The chimney

    The combustion process in furnaces produces smoke and exhaust gases that have to be discharged into the open air.

    This is done via a corresponding exhaust system or an exhaust system.

    A chimney is a soot fire-resistant exhaust gas system made of stainless steel, ceramic or chamotte, which is suitable for all types of fuel, including solid fuels such as logs, pellets, wood chips and charcoal.

    In the case of heating systems for liquid or gaseous fuels, a so-called exhaust pipe can also be used as an alternative. Due to the lower exhaust gas temperatures, in addition to stainless steel, it is usually possible to use PP pipes and, if necessary, the corresponding sealing material made of silicone or EPDM, which makes an exhaust pipe suitable for overpressure depending on the requirements of the fireplace.

    Jeremias provides a wide variety of flue gas systems in order to perfectly match the chimney or the flue gas pipe to the connected combustion system, the type of fresh air supply, the fuel used and the installation location.

    Functionality

    Functioning of a chimney

    All chimneys work according to the same basic principle, the so-called Bernoulli effect (chimney effect).

    During the combustion process, fireplaces create a natural draft that automatically discharges the exhaust gases to the outside via the chimney.

    This is made possible by the fact that heated air and hot exhaust gases are less dense than the ambient air and therefore rise upwards (thermal convection). The resulting negative pressure in the fireplace / chimney allows cold fresh air to flow into the fireplace and thus ensures that the combustion process is maintained at all times.

    In practice, how strong this effect is depends on various factors, such as the height of the chimney, the dimensions of the chimney, exhaust gas velocity or the difference between exhaust gases and the combustion air supplied in terms of density and temperature.

    For the perfect interplay between fireplace and chimney, an individual calculation of the appropriate chimney cross-section is essential. This is the only way to ensure sufficient draft that safely guides the exhaust gases to the outside.

    Basics for choosing a chimney

    Things to consider before buying a chimney

    The heating and exhaust system together form a system and must be perfectly coordinated for efficient and safe operation. Before selecting the right chimney or flue gas pipe, there are a few points to consider.

     

    Fuel

    A key selection criterion when choosing the right exhaust system is the fuel used for heating. The fuels that can be used for heating can be differentiated according to their origin.

    Fossil fuels were created millions of years ago from dead plants and animals and consist mainly of carbon and hydrogen. They represent a finite source of energy and when burned release large amounts of stored CO2. Fossil fuels include coal, oil and natural gas.

    Biomass, on the other hand, refers to regenerative fuels that were still actively involved in the carbon cycle before they were used, which is why they are also classified as "CO2-neutral". Well-known biomass representatives are wood (logs, pellets, woodchips), plants grown specifically for energy production such as corn, grain and elephant grass, as well as organic waste of all kinds.

     

    Exhaust temperature

    The choice of fuel has a decisive influence on the exhaust gas temperature and thus also on the pre-selection of the appropriate exhaust system.

    Gas or oil heaters run with significantly lower exhaust gas temperatures than furnaces that are operated with solid fuels such as wood or coal. This applies all the more to gas/oil condensing boilers, which use the energy used very efficiently, which ensures even lower exhaust gas temperatures.

    Brick chimneys or conventional chimneys made of concrete require a high flue gas temperature of 356°F - 392°F at the chimney inlet, so that the temperature at the chimney outlet does not fall below the dew point. Otherwise condensate would form in the chimney and in the long term there would be a risk of moisture penetration or even the chimney becoming sooty. They are therefore only suitable for dry operation, i.e. for solid fuels with a correspondingly high exhaust gas temperature.

    Jeremias stainless steel chimneys are also suitable for high flue gas temperatures, but thanks to the moisture-resistant material, they can also be used in conjunction with modern condensing boilers where the flue gas temperatures hardly ever reach 176°F and condensation in the chimney is even desirable (humid or condensing operation). The same applies to our plastic exhaust systems.

     

    Pressure tightness

    The low flue gas temperatures of modern condensing boilers may lead to the natural chimney draft being inhibited, because colder air rises much harder than the warm flue gases from solid fuel fireplaces, for example.

    In order to ensure that the flue gases can escape unhindered to the outside and that combustion is problem-free, most modern condensing boilers have an integrated fan. This supports the chimney effect and ensures overpressure in the exhaust pipe, which makes the use of pressure-tight exhaust systems necessary.

     

    Soot fire resistance

    Burning solid fuel produces soot, which settles in the chimney. If dry firewood is used, the soot deposited in the exhaust pipe can be easily removed by the chimney sweep.

    However, if you use fuel that is too moist or unsuitable, moist soot will also be deposited on the inner wall of the chimney. Due to its moisture content, this initially poses no danger, but usually cannot be completely removed with conventional sweeping equipment. If it then hardens with increasing exhaust gas temperature, it becomes a highly flammable hazard. Normal flying sparks from the burning process can then trigger a soot fire with meter-high flames at the top of the chimney and temperatures of well over 1000°C in the chimney.

    Chimneys for dry operation with solid fuels must be able to withstand such a soot fire without damage such as cracking, otherwise they would be unusable afterwards.

    The classification of the exhaust system provides information about the soot fire resistance.

    All Jeremias systems that are generally approved for dry operation are soot fire-resistant or insensitive to moisture if they are used in condensing operation.

    Flue gas systems that are not soot fire-resistant, such as plastic systems, on the other hand, may only be connected to fireplaces for liquid or gaseous fuels when they are in wet operation.

     

     

    Exhaust system diameter

    Today's cooler exhaust gas temperatures would usually no longer be sufficient for the safe discharge of exhaust gases to the outside in the large chimneys that were common in the past.

    In order to obtain the desired chimney draft, smaller chimney diameters are required for today's modern fireplaces with lower flue gas temperatures. These should be determined by the specialist company using a cross-section calculation adapted to the respective fireplace.

     

    Chimney height

    The chimney height also has a significant influence on the draft behavior of the chimney. Basically, the higher the chimney, the better the chimney draft.

    The respective minimum requirements for the chimney height must be observed.

     

    Room air dependent or room air independent operation

    Fireplaces can draw the air they need for combustion either from the living space (room air-dependent) or via a supply air duct from outside the building (room air-independent).

    The advantage of room air-independent operation is that the usual requirements for the minimum air volume of the installation room can be omitted and the simultaneous operation of a combustion system and a ventilation system or an exhaust air extractor system is possible without any restrictions.

    The fresh air can be supplied either via a separate supply air system or via a concentric flue gas system (also known as a LAS chimney), in which the supply air is routed to the fireplace via the annular gap between the flue gas pipe and the outer pipe.

     

    Acceptance

    When installing a heating system including an exhaust gas system, a number of important regulations must be observed. For example, the minimum distances to combustible components are clearly defined and must be observed. In addition, it must be ensured that the flue gas system fits the heating system, that no flue gases can penetrate the living space, that the supply of oxygen is guaranteed, that the specifications for chimney placement and height are complied with and much more.

    It is therefore advisable to call in the responsible district chimney sweep as an advisor as early as the planning phase. He has to accept the entire system before it is put into operation for the first time and can give valuable tips on installation. The installation itself should then ideally be carried out by a qualified specialist company.

    Chimney types

    Stainless steel chimney - The chimney of the present and future

    The brick fireplace is not very flexible due to its nature. The position in the building cannot be changed afterwards and the connection points are therefore also fixed. As a result, when a new stove or other fireplace is connected, the installation position can be selected to a very limited extent. In such cases, the stainless steel chimney has established itself as a flexible flue gas system that can be retrofitted. A double-walled stainless steel chimney from the Jeremias company particularly stands out here. Insulation placed between the exhaust gas-carrying inner pipe and the outer pipe prevents the exhaust gas from cooling down too much in the double-walled chimney, which is usually used as an outdoor chimney, and thus ensures that the chimney draft continues. By using the highest quality materials and the most modern production methods, a chimney with a premium claim is manufactured. 

     

    Single wall exhaust system for chimney relining

    An additional application is the chimney renovation of existing brick fireplaces, which can become sooty or otherwise unusable due to many years of use and other reasons. These fireplaces can be renovated with a single-walled stainless steel chimney. The stainless steel pipe is simply pulled into the brick chimney, creating a new exhaust system and saving the existing chimney for many years to come.

     

    Furnace pipes, chimney covers, exhaust silencers - all-round care with Jeremias

    In addition to the exhaust systems mentioned, Jeremias also offers an extensive range of products for everything to do with exhaust technology. The offer ranges from various supply systems such as the stovepipe of the FERRO-LUX series to exhaust silencers for private and professional users.

    The stovepipes are provided with a special Senotherm coating and fired at the factory. This means that the stovepipe does not develop any unpleasant odors when it is used for the first time. A wide range of inner diameters is available so that all types of stoves can be connected. The range of stovepipes includes around 100 individual parts. This means that every individual connection situation can be taken into account and the on-site effort can be kept to a minimum.

    Chimney covers such as the well-known Napoleon hood or the Meidinger disc are made of high-quality stainless steel and protect the chimney top of brick fireplaces. Here, Jeremias exhaust technology GmbH offers many different models. What they all have in common is that the respective chimney cover is manufactured according to customer requirements. Thus, the optimal fit and protection can be guaranteed. As usual at Jeremias, only corrosion-resistant stainless steel is used for these components. This, in combination with the high-quality workmanship, results in an extremely durable product.

     

    Steel chimney - from the vision to the individual solution

    In addition to the stainless steel chimney, Jeremias is also a manufacturer with decades of experience in the field of steel chimneys. After more than 20 years in the industrial sector, we enable different complex solutions for customers all over the world. Our experts provide advice on everything from chimney design and planning to production and turnkey assembly. Jeremias develops the optimal solution for every chimney project.

    Our range of services for the industrial chimney includes the complete project management, consulting and planning, construction, production, transport, assembly and maintenance with condition monitoring.

    Membership in the IVS (Industrial Association for Steel Chimneys) offers manufacturers like Jeremias the opportunity to incorporate suggestions for improvement and wishes into standardization and at the same time always be up to date - and at least one step ahead.

    Advantages Element chimneys made of stainless steel

    Advantages Element chimneys made of stainless steel

    Jeremias' modular flue gas systems have many advantages over welded alternatives and chimneys from many other manufacturers.

    With over 100 CE and UL-certified systems, supplemented by building authority approvals, country-specific certifications and special approvals, e.g. for the maritime sector, Jeremias probably offers the largest selection on the market.

    Jeremias element chimneys are easy to assemble due to the low weight of the individual chimney elements and precisely fitting plug-in connections. No on-site welding is required for installation and heavy lifting equipment can be dispensed with in most cases.

    Element chimneys can be expanded and lengthened at a later point in time. In addition to standard parts, custom-made products are also possible at any time, depending on requirements.

    Through the exclusive use of corrosion-resistant stainless steel alloys, Jeremias offers the highest possible security against damage and the associated functional impairments of the chimney, which is why we can also give a limited lifetime warranty on the corrosion resistance of our stainless steel products.

    With our double-walled chimneys, rigid insulation shells made of high-quality mineral wool, available in different thicknesses, prevent the formation of thermal bridges between the inner and outer shell and also allow the chimney to be installed at a short distance from combustible materials.

    TIG inert gas welded and passivated longitudinal seams guarantee condensate and gas tightness of our exhaust pipes. The use of high-quality sealing materials also ensures that our overpressure systems have a long service life.

    Thanks to our own test laboratories for thermal, static and acoustic (exhaust silencer) tests, we are able to bring innovations to the market quickly and with tested safety and to guarantee the consistently high quality of our products.

    An extensive range of accessories completes the Jeremias portfolio of chimney elements.

    History of chimneys

    Brief overview of the history of its origin

    The development of smoke disposal through the chimney runs parallel to the historical development of the use of fire for heating purposes.

    While in antiquity up to the 14th century the smoke usually had to find its way out through door and window openings or an opening in the ceiling or the roof, there were vertical brick shafts through which fire and smoke gases were discharged as early as 1000 AD in the case of the duct heating in the imperial house in Goslar.

    Due to the increasing use of stones as a building material instead of the usual timber, the fireplace was moved from the middle of the room to the wall, which served as the so-called fire wall. The smoke was caught by a protective roof and channeled outside through the roof beams. For reasons of fire protection, the firewalls were soon made of two shells in the area of ​​the hearths and thus became smoke outlets (scraping) through which the smoke gases could be discharged to the outside without any danger. At first people spoke of the so-called smoke tubes, and the word chimney in its current meaning only appears in documents from the 15th century.

    Craftsmen (e.g. bakers, blacksmiths) found out very quickly that a brick vertical flue supplied more combustion air to the fire and removed the smoke better. In the Middle Ages, such drainage shafts were usually installed in the retaining walls of castles and palaces.

    With the first iron stoves in the 15th century, heat was used more efficiently, but there was also a significant hazard from the hotter smoke gases and the chimneys, which at that time were still largely made of combustible materials (wooden staves, wooden boards coated with clay).

    In Germany, a royal instruction for the first time in 1822 brought more precise implementation regulations about the smallest permissible width, thickness of the chimney and the necessary cleaning. As a result, requirements were placed on structural strength and fire safety for the first time. At that time, the chimney caps were usually adapted to the style of the building, but did not always take functional requirements into account.

    In the 20th century, the use of fuel changed from wood to coal to heating oil and natural gas. This change and the technical development and modernization of fireplaces from individual stoves to central heating also required changes in chimney technology.

    For a long time, the most common form was the single-walled chimney. For a long time, this simple system, consisting either of a brick bond or of shaped blocks placed one on top of the other without additional insulation, was sufficient, although never ideal, because the risk of cracking due to temperature stresses was always present. For reasons of simpler and faster assembly, this type of construction was replaced by the use of single-shell, solid-walled fittings or single-shell chimneys made of cell fittings.

    The first serious turning point came in the late 1950s and early 1960s. More and more heating systems have been switched from solid fuel to oil.

    The result: the temperature in the chimney and the exhaust gas mass flow decreased noticeably. The temperature fell below the dew point, particularly in the roof and overhang area of ​​the chimney, which led to moisture (condensation). Water mixed with aggressive exhaust gas residues condensed on the inner walls of the chimney and slowly but surely caused the construction to become damp. There were signs of sooting on a considerable scale.

    It became even more problematic in the late 1970s and early 1980s when heating costs skyrocketed as a result of the first major energy crisis.

    At the same time, there was a fundamental change in the use of energy sources. The proportion of gas-powered heating systems increased steadily. Growing environmental awareness did the rest. It became clear that the CO2 released when burning fossil fuels is largely responsible for the so-called greenhouse effect.

    From the point of view of environmental protection, there was a need to noticeably reduce the energy consumption for heating the building. The industry reacted and within a short time brought a new, much more economical generation of boilers onto the market.

    Since the flue gas temperatures of the new boilers were considerably lower than those of the previous models, the load on the flue gas pipe and the chimney increased again.

    Another complicating factor was the higher water vapor content of the flue gases. When oil was used in the past, about 7% water vapor had to be expected in the flue gas, while gas as a fuel is about 14%.

    Due to changing heating technology and the associated increase in chimney damage, a wide variety of renovation methods geared to the new conditions have been developed. By far the most popular renovation method today is to pull a stainless steel pipe into an existing chimney from the top of the chimney.

    The development continued to three-shell house chimneys. With these, an inner pipe made of stainless steel or fireclay was placed centrally in a masonry shaft or a shaped casing and the remaining space between the wall and the inner pipe was filled with insulating material.

    This measure reduced temperature stresses (overheating of the outer chimney walls).

    Due to the increasing use of oil and gas as well as new heating technologies, the chimney that had previously been run "dry" became a "wet" chimney with hot, dry exhaust gases. In addition to the requirements for stability and fire safety, acid resistance, condensate tightness and thermal insulation also had to be met. This led to the development of multi-layer chimney systems, consisting of an outer shell, insulation and flue pipe, in which the stress is distributed over the various components. Each component fulfills its own special task:

    • The inner shell (the flue pipe) is acid-resistant and condensate-tight, if necessary also pressure-tight if the exhaust system is operated at overpressure
    • The thermal insulation ensures that the exhaust gases cool down slightly and prevents or reduces the formation of condensate. In the case of overpressure systems, the insulation gives way to continuous rear ventilation
    • The outer shell (the cladding or the mantle stone) takes on the static concerns and, together with the insulation, the fire protection and also the sound insulation

    These double-walled chimneys could no longer be built at will from the building materials available at the time, but became officially approved flue gas systems in which the individual components had to be coordinated with one another. Only after detailed tests and proof of their usability do these systems receive their approval or their CE certificate.