EP0315577B1 - Burner heated apparatus, especiallly water heater - Google Patents

Abstract

In a burner-heated apparatus with a heat exchanger (3) which is arranged in the waste gas guide (2) of the burner (1), which leads to a chimney (5) or similar waste gas take-off, and is flowed through by the waste gases of this burner (1), a portion, which can be selected as required, of the waste gases from the combustion chamber (8) is conducted directly into the chimney (5) or similar waste gas installation, in order that the temperature there is not allowed to fall below the dew point and as a result the formation of condensate is prevented. The size of this waste gas portion to be conducted off directly into the chimney (5) or similar can be defined from case to case taking the respective local conditions into consideration. The supply of uncooled waste gases can take place via a bypass guide (9) or the heat absorption capacity of the heat exchanger (3) can be reduced selectively. <IMAGE>

Description

The invention relates to a burner-heated device, in particular a water heater, with a heat exchanger arranged in the exhaust gas routing of the burner leading to a chimney or similar exhaust gas outlet, through which exhaust gases from this burner flow, and a combustion chamber located below the heat exchanger.

A boiler with these structural features is known from DE-OS 3604842. In this boiler, the flue gas temperature is to be adapted to existing chimney systems in such a way that the flue gas flow is divided into a main flow flowing through the main heat exchanger and a secondary flow at least partially bypassing it. The disadvantage here is that only a certain increase in the exhaust gas temperature that cannot be changed subsequently can be achieved in this way. Another problem is the adaptation of the boiler to possibly very different structural conditions of the chimney.

The object of the invention is to prevent condensation forming in the chimney as a result of the temperature falling below the dew point. Such condensation forms a gradual sooting of the chimney, which destroys the chimney wall and forces its costly renovation.

The invention is based on the knowledge that, in order to prevent this condensate formation, an increase in the temperature of the exhaust gases that is sensitive to the respective local nature of the fireplace is required, provided that the fireplace, as in old buildings, for example, is not optimal and therefore at comparatively low exhaust gas temperatures tends to soot.

In the case of devices operated with a fan, the accumulation of condensate in the exhaust gas outlet should be avoided or at least reduced as far as possible.

In accordance with the invention, for such a locally individually adjustable increase in the temperature of the exhaust gases supplied to the chimney or the like exhaust gas exhaust from the combustion chamber, a bypass guide which opens directly into the chimney or the like and bypasses the heat exchanger is branched off, in which the size of the throughput of the portion to be supplied directly to the chimney the exhaust gas regulating control element, for example a slide valve or throttle valve, is arranged.

The size of this portion can therefore be selected and adjusted as desired, so that the temperature of the exhaust gases flowing through the chimney or similar exhaust gas outlet can be adjusted to an optimum value above the dew point, at which, on the one hand, no condensate formation is to be feared, but on the other hand there are no excessive heat energy losses.

The heat exchangers of devices of the type mentioned at the outset are known to be supplied with the device in which they are installed as standard and are dimensioned uniformly, regardless of the installation location. Thanks to the solution according to the invention, the exhaust gas temperature of such devices can now be set individually to the respective local nature of the fireplace with little expenditure of time and effort so that the exhaust gas temperature within the fireplace does not fall below the dew point and, consequently, no condensate is produced.

In order to raise the flue gas temperature in the area of the chimney to a temperature sufficient to prevent the formation of condensate, it is only necessary to increase the proportion of the flue gases leading directly to the chimney.

In order to make the device compact and space-saving with this bypass guide, the bypass guide is expediently arranged essentially parallel to the exhaust gas guide containing the heat exchanger.

This subsequently opens up the advantageous possibility of guiding this bypass in addition to the exhaust gas duct containing the heat exchanger from the combustion chamber to a common exhaust gas collector, from which the exhaust gas outlet or the chimney connection then originates.

In the context of the invention, the bypass guide can easily be formed by the components of the heat exchanger, for example the members of a sectional boiler, but this bypass guide can also be conducted separately and at a distance from the exhaust gas guide containing the heat exchanger from the combustion chamber of the burner directly into the exhaust gas collecting chamber .

By means of the adjustable control element arranged in the bypass guide, for example a slide, a throttle valve or the like, the portion of the uncooled exhaust gases to be fed directly to the exhaust gas outlet and the chimney can be conveniently and easily adjusted to its optimum size.

According to other embodiments of a device according to the invention, the capacity of the initially uniformly dimensioned heat exchanger can be purposefully changed and optimally adjusted, taking into account the respective local conditions and the nature of the fireplace, in order to solve the initially defined task.

In this regard, various design options are available within the scope of the invention, with the aid of which it is possible to ensure that a portion of the exhaust gases of a size that can be determined reaches the exhaust manifold and into the chimney or the like without cooling through the heat exchanger, to prevent condensation and sooting.

In the case of a heat exchanger which usually consists of a group of fins with fins, it should be provided according to the invention that a partial area of the surface of the heat exchanger has little or no fins, so that uncooled exhaust gases can reach the chimney to a measurable extent within this area.

In this partial area, for example, some of the fins can be used to measure the heat absorption capacity as required of the heat exchanger to be releasably connected to the tubes carrying them. In order to then increase the flue gas temperature in the chimney to a level sufficient to prevent condensation, only a variable number of such releasable fins need to be removed, or only so many releasable fins can be used in a finned-free area of the pipes that the exhaust gases in this partial surface area do not cool down significantly, at least not below the dew point.

According to a preferred embodiment, the fins can be plugged onto the pipes and releasably connected to the pipes by frictional engagement.

In order to prevent such detachable slats from being arranged too closely, which would cause locally excessive temperatures and poor heat transfer, a detachable slat should be insertable between two or more stationary slats.

Another possibility for realizing the inventive idea is to make walls of the fins extending between adjacent tubes removable in some areas, in order to reduce their heat-transferring area as required and to be able to increase the temperature of the exhaust gases leaving the heat exchanger.

In this case, no additional slats that can be detachably fastened are required, but only the existing, stationary slats need to be slightly processed.

In order to facilitate the removal of removable wall parts of the lamellae, punched-out sections can be provided in these lamellae, preferably punched-out paired angles to separate approximately triangular or trapezoidal wall parts.

To facilitate the handling of the wall parts to be separated, the arrangement of a transverse punching in the removable wall part is recommended.

Furthermore, it is advantageous for the function of a heat exchanger to arrange the fins with the removable wall parts in a limited, preferably central, partial surface area of the heat exchanger.

According to other embodiments of the subject matter of the invention, the throughput of the exhaust gases can be throttled by a part of the heat exchanger to increase the temperature occurring in the chimney as required.

With this objective, it can be provided, for example, according to a further embodiment, in a device whose heat exchanger is attached to at least one, in particular water-carrying, heat exchanger, fins parallel to the exhaust gas flow, that at least one space enclosed by fins needs to be enclosed by a free outer edge at least one of these fins, the wall extending transversely to the plane of these fins, can be at least partially limited.

With this measure, an arbitrarily large part of the spaces which are otherwise flowed through by the exhaust gases and which are formed between the fins can be blocked, in each case to a selectable extent, which ensures a sufficiently high temperature of the exhaust gases leaving the heat exchanger.

Depending on the desired extent of this blocking, this wall can only extend over part of the distance formed between adjacent slats or over the full distance. In the latter case, the wall can also extend over several distances formed between adjacent lamellae. The extent of the blocking of the heat exchanger can therefore be regulated extremely sensitively within the scope of the invention with very simple measures in order to achieve an exhaust gas temperature in the chimney which prevents its sooting, on the other hand, it does not result in excessive energy losses.

If the inner edge of the fins facing the heat exchange tube has a collar attached to the tube wall, it is advisable to have the wall attached to the outer edge of these fins point to the side opposite this collar.

If the heat exchanger consists of a block of heat exchange tubes through which the fins pass, then it is advantageous to attach the walls to the fins in the edge region of this block.

In general, it is advisable to attach these walls predominantly downstream in the flow direction of the exhaust gases, ie on the side of the fins facing away from the combustion chamber.

According to a further embodiment of the subject matter of the invention, which is tailored to a targeted reduction in the heat exchangeability of the heat exchanger, at least one cover plate arranged on the heat exchanger, for example a heat-resistant sheet metal plate, is provided, which extends over, preferably opposite, edge regions or the central region of the surface of the heat exchanger .

The surface area to be covered with such a plate, optimal from case to case, in which, on the one hand, a drop below the dew point in the chimney or the like is avoided, but on the other hand the losses of exhaust gas heat are still justifiable, can either be determined from the outset for the locally specified conditions or can be fixed by a fixed installation of the cover plate, or such a plate can be arranged in an adjustable manner to prevent the throughput of the exhaust gases, in order to be able to fix it in a throttle position that can be optimally selected as required. In any case, such a cover plate can always be retrofitted to an existing heat exchanger without any problems.

The arrangement of such cover plates on the heat exchanger is fundamentally arbitrary within the scope of the invention, that is to say they can extend over the edge regions of the heat exchanger, for example be arranged laterally, at the front and / or rear of the heat exchanger, for example also in adjacent edge regions.

However, in order to achieve as even a distribution of the throttling of the throughput as possible, it is advisable to arrange such plates symmetrically with respect to the surface of the heat exchanger, for example in pairs.

If the plates are adjustable to regulate the extent of the throttling as required, it is advisable to mount them so that they can be easily pivoted about a horizontal axis.

In practice, it is advantageous to first supply the gas-fired devices with a heat exchanger, the efficiency of which corresponds to the optimal condition of the existing fireplace or similar flue gas extraction, and then to increase this efficiency at the installation site of the device by setting or dimensioning the cover plate (s) Reduce that a drop below the dew point in the chimney is reliably prevented. In the event of a later refurbishment of the fireplace, the exhaust gas temperature within the exhaust gas outlet can be adapted, namely reduced, to its new state at any time.

According to a further feature of the invention, at least one edge region of the heat exchanger can be covered by at least one insert arranged on its underside in the upper part of the combustion chamber. Such an insert can advantageously contribute to the insulation of the combustion chamber and thereby reduce the heat loss in this area and increase the temperature of the exhaust gases flowing off.

In order to cover a selectable portion of the heat exchanger, the insert attached to the preferably cooled and / or insulated wall of the combustion chamber can have a width that increases upwards against the heat exchanger and covers an edge region of the heat exchanger.

To further ensure that as little heat as possible is given off to the surroundings of the device, rather remains in the exhaust gases flowing to the chimney and contributes to an increase in the exhaust gas temperature in the chimney and thus to a reduction or avoidance of condensate formation, according to further features of the invention The top of the heat exchanger, preferably within an exhaust manifold, has baffles which, due to their surface, shape and installation position, allow the absorbed radiation to be emitted and the incident heat to be reflected in the exhaust gas stream, thereby increasing the exhaust gas temperature.

A baffle directed diagonally upwards against the inlet of the chimney or exhaust fume and / or a baffle arranged at a distance from the inlet of the chimney or exhaust fume, which has a transverse to its axis, allows a flow to occur within the exhaust gas collector, which favors the absorption of the radiant heat and also a uniform flow of the upstream heat exchanger guaranteed.

Furthermore, the exhaust manifold can advantageously be insulated to reduce the temperature of its outside, most simply by designing its hood with two shells up to the exhaust gas outlet, in order to thereby reduce the radiation and to ensure high exhaust gas inlet temperatures in the exhaust gas outlet. The inner shell can then be designed in such a way that it fully takes over the function of the above-mentioned guide plates.

All these measures contribute through their sensible application that the residual heat still remaining in the exhaust gases after flowing through the heat exchanger is not lost and when the exhaust gases enter the chimney a high exhaust gas temperature is available which prevents the dew point in the chimney from falling below the dew point.

Finally, it is advantageous within the scope of the invention to provide a plate which is divided into lamellae, can be inserted, preferably inserted, into the exhaust gas duct and is used for heat absorption and radiation, and / or a frame fitted with lamellae, which enables the exhaust gas temperature to be corrected according to the nominal heat output that is set , namely by reducing or increasing the free exhaust gas flow cross section and thus the heat transfer surface of the heat exchanger.

According to a preferred embodiment, the plate and the frame are assigned to one another, at least one of the two parts being displaceably mounted in relation to the other part within the exhaust gas duct in order to be able to measure the flow cross section in a targeted manner.

With the aid of such a device, it is also possible to carry out a pressure loss-dependent control of the exhaust gas flow from the combustion chamber directly into the exhaust manifold. For this purpose - according to a further feature of the invention - a bypass for part of the exhaust gases flowing through the exhaust gas duct is provided on the side of the heat exchanger and the above-mentioned plates or frames in the exhaust gas duct, through which this portion reaches the chimney without flowing through the heat exchanger.

Figur 1

eine erste Ausführungsform eines erfindungsgemäßen Gerätes in einem schematischen Vertikalschnitt und

Figur 2

stellt eine abgewandelte Ausführungsform dieses Gerätes dar.

Figur 3

zeigt den Wärmetauscher einer zweiten Ausführungsform schaubildlich und

Figur 4

ein zugehöriges Detail in einer Ansicht.

Figur 5

zeigt eine abgewandelte Ausführungsform dieses Wärmetauschers gleichfalls schaubildlich und

Figur 6

ein Detail in größerem Maßstab.

Figur 7

ist eine Draufsicht auf einen beispielsweise in einer senkrechten Abgasführung eines Gerätes angeordneten Wärmetauscher und die

Figuren 8 bis 10

zeigen Vertikalschnitte durch einen Teil eines Wärmetauschrohres solcher Wärmetauscher in verschiedenen Varianten.

Figuren 11 und 12

zeigen Wärmetauscher, bei denen zur Drosselung des Abgasdurchsatzes Abdeckplatten Verwendung finden.

Figur 13

stellt den oberen Teil einer Brennkammer mit Abgasabzug und mit dem in der Abgasführung angeordneten Wärmetauscher in einem Vertikalschnitt dar,

Figur 14

zeigt den oberen Teil einer Brennkammer mit dem daran anschließenden Abgasabzug, gleichfalls in einem Vertikalschnitt.

Figur 15

ist die Draufsicht auf ein in eine Abgasführung einsetzbares, in Lamellen gegliedertes Blech und

Figur 16

zeigt dessen Querschnitt nach XVI-XVI der Figur 15.

Figur 17

stellt eine Ausführungsvariante einer solchen Platte in einer Untersicht dar und

Figur 18

ist ein Schnitt nach XVIII-XVIII der Figur 17.

Figur 19

ist teils ein Schnitt nach XIX-XIX der Figur 20 durch einen mit solchen Platten ausgestatteten Wärmetauscher, teils dessen Seitenansicht und

Figur 20

ist ein Waagschnitt nach XX-XX der Figur 19.

The subject matter of the invention is explained below on the basis of exemplary embodiments which are illustrated in the drawings. Show in detail

Figure 1

a first embodiment of a device according to the invention in a schematic vertical section and

Figure 2

represents a modified embodiment of this device.

Figure 3

shows the heat exchanger of a second embodiment diagrammatically and

Figure 4

an associated detail in a view.

Figure 5

shows a modified embodiment of this heat exchanger also graphically and

Figure 6

a detail on a larger scale.

Figure 7

is a plan view of a heat exchanger arranged, for example, in a vertical exhaust gas duct of a device and

Figures 8 to 10

show vertical sections through part of a heat exchange tube of such heat exchangers in different variants.

Figures 11 and 12

show heat exchangers in which cover plates are used to throttle the exhaust gas flow.

Figure 13

represents the upper part of a combustion chamber with exhaust gas extraction and with the heat exchanger arranged in the exhaust gas duct in a vertical section,

Figure 14

shows the upper part of a combustion chamber with the flue gas outlet connected to it, likewise in a vertical section.

Figure 15

is the top view of a sheet metal, which can be inserted into an exhaust gas duct and is divided into fins

Figure 16

shows its cross section according to XVI-XVI of Figure 15.

Figure 17

represents a variant of such a plate in a bottom view and

Figure 18

is a section along XVIII-XVIII of Figure 17.

Figure 19

is partly a section according to XIX-XIX of Figure 20 through a heat exchanger equipped with such plates, partly its side view and

Figure 20

is a horizontal section according to XX-XX of Figure 19.

A water heater shown for example in Figures 1 and 2 consists essentially of the burner 1, e.g. a gas burner, and from a heat exchanger 3 arranged in its exhaust duct 2, which e.g. pipes, plates or the like, water-carrying members, which are equipped with ribs, needles or the like. The organs favoring the heat exchange can consist of limbs, the outside of which are washed around by the exhaust gases.

These exhaust gases flow to a hood-shaped exhaust manifold 4 with an exhaust gas outlet opening into a chimney 5. The forward and return flow of the heat exchanger 3 belonging to a heating circuit is designated 6 and 7, respectively.

In order not to let the temperature of the exhaust gases in the chimney 5 drop below the dew point and thereby prevent the formation of condensate in the chimney 5, a selectable proportion of the hot exhaust gases generated by the burner 1 in the combustion chamber 8 of the device is necessary via a bypass guide 9 the combustion chamber 8 directly, that is, bypassing the heat exchanger 3, into the exhaust manifold 4.

According to FIG. 1, a regulating member 10, for example designed as a slide, is provided at the outlet of the bypass guide 9, according to FIG. 2, however, there is an adjustable throttle valve as a regulating member 10 in the bypass guide 9.

The setting of such control elements 10 can be carried out within the scope of the invention when the device is installed, depending on the nature of the locally existing fireplace, but it could also, if necessary automatically controlled, depending on the temperature the flue gases in the chimney can be controlled depending on the operating and / or time or depending on other physical parameters.

The bypass guide 9 can be designed as desired within the scope of the invention. For example, according to FIG. 1, it can consist of components of the heat exchanger, e.g. be formed by the links of a link boiler and consist of castings of such links.

However, as shown in FIG. 2, this bypass guide 9 can also be guided separately and at a distance from the exhaust gas guide 2 containing the heat exchanger 3 from the combustion chamber 8 of the burner 1 into the exhaust gas collecting chamber 4.

However, the task defined at the outset of increasing the exhaust gas temperature in the chimney as required can also be achieved within the scope of the invention by a targeted reduction in the heat absorption capacity of the heat exchanger.

In detail, FIG. 3 shows a heat exchanger 3 with a family of parallel water-carrying pipes 11 which are covered with fins 12. At the opposite ends of these tubes 11 there is on the one hand a distributor 13 and on the other hand a collector 14 to which the return 7 or the flow 6 of a heating circuit connect. The exhaust gas of the burner-heated device flows through this heat exchanger 3 upwards in the direction indicated by an arrow to the exhaust gas collector and to the chimney.

A partial surface area 15 of the total area of the heat exchanger 3 is designed to be lamella-free, and in this area 15, fins 16 which can be plugged on as shown in FIG. 4 can be attached can be attached to the tubes 11 in any number.

Because these fins 16 are only plugged on, they do not serve fully, but only partially for heat exchange. Above all, however, they reduce the free cross section for the throughput of the exhaust gases.

The heat exchange capacity of the heat exchanger 3 can thus be fine-tuned to the respective local nature of the fireplace or the like. The heat of the exhaust gases coming into the chimney or the like is influenced by the respective size of the area 15 which remains free of lamellae and through which part of the exhaust gases flows largely uncooled to the exhaust gas collector and which can be reduced or reduced as required from case to case by inserting the releasable fins 16 can be enlarged as desired by removing existing detachable slats 16.

According to FIGS. 5 and 6, in a surface area 17 of the heat exchanger 3, wall parts 18 of the fins 12 extending between adjacent tubes 11 can be removed if necessary, punched portions 19 of the fins 12 running in pairs and at an angle to one another being provided to facilitate the separation of such approximately triangular wall parts 18. A further, transverse punching 20 serves to facilitate the handling of the wall parts 18. According to FIG. 7, water-carrying heat exchange tubes 11 are equipped with fins 12 which run parallel to the flow of the in a Exhaust gas duct 2 are aligned from a combustion chamber of a burner-heated device to a chimney-flowing exhaust gas. In the area of the pipe passages, the lamellae 12 have collars 21 with which they are fastened flat against the pipe wall.

In the exemplary embodiment shown, the exhaust gas flow runs vertically upwards, but could also run vertically downwards or horizontally in the case of a fan-operated burner.

The fins 12 have - in the direction of the exhaust gas flow downstream - edges 22 and - in the direction of the exhaust gas flow upstream - edges 23 which face the combustion chamber. In the exemplary embodiment shown, the edges 22 are accordingly at the top and the edges 23 at the bottom.

The fins 12 are made of copper or stainless steel in the same way as the tubes 11. Each lamella 12 is penetrated by a plurality of tubes 11 which are parallel to one another. In this way, the fins 12 of the heat exchanger 3 form a block, which is delimited on the long sides by a frame 24.

Individual slats 12, in particular arranged in the edge region of this frame 24, now have a wall 25 running transversely to their plane and attached to one of their free edges, which at least partially delimits the space 26 enclosed by two adjacent slats 12.

These walls 25 accordingly block the exhaust gas flow through these spaces 26 and in this way reduce the efficiency of the heat exchanger 3 as required and thereby increase the temperature of the exhaust gases flowing into the chimney.

These walls 25 can be formed in the simplest way by flanges attached to the edge of the lamellae 12. These flanges can be arranged both on the edge 22 facing the combustion chamber, ie upstream of the exhaust gas flow, according to FIG. 7, and on the edge 23 facing away from the combustion chamber, i.e. downstream of the exhaust gas flow, according to FIGS. 8 to 10.

If the fins 12 on their inner edge, that is on the edge of the openings through which the tubes 11 are attached, by means of collars 21 on the walls of the tubes 11, then the wall 25 attached to their outer edge should point towards the side opposite this collar 21 thereby strengthening the stability of the lamella 12.

While FIGS. 7 to 9 show embodiments in which the walls 25 extend only over part of the distance between adjacent slats 12, these walls 25 run according to FIG. 10 over the full distance and over several slats 12, so that they are some between these slats 12 completely close the spaces 26 formed and block them for the exhaust gas flow. According to FIG. 10, these walls 25 can therefore also extend over a plurality of lamellae 12.

The respectively desirable extent of the increase in the temperature of the exhaust gases entering the chimney must be matched to the local nature of the chimney from case to case by selecting the number and arrangement of the walls 25.

Water to be heated is fed to the lamella block according to FIG. 7 via the return 7 of a heating circuit, which passes through the distributor 13 into the heat exchange tubes 11 and flows through the exhaust gas duct 2 in these tubes 11 and passes via the collector 14 into the flow 6 of the heat exchanger 3.

The spaces 26 to be blocked by means of the walls 25 can be located within the scope of the invention of the frame 24 near the side of the heat exchanger 3 (FIGS. 8 and 9) or in the middle of the exhaust gas duct 2, as shown in FIG. 10.

According to FIG. 11, a cover plate 27 is placed on the top of a flat heat exchanger 3, which covers the four edge areas in a surface area that can be selected as required and thereby blocks the throughput of the exhaust gases in these edge areas, thus reducing the heat absorption capacity of the heat exchanger and the cooling of the exhaust gases.

The dimensions of this cover plate 27 are to be chosen from case to case in such a way that the exhaust gas temperature above the heat exchanger 3 only increases to such an extent that a drop below the dew point in the chimney or the like and, as a result, the formation of condensate there is reliably prevented.

According to the embodiment according to FIG. 12, two abutting, adjacent edge regions of the heat exchanger 3 can be covered by adjustable cover plates 28, which are pivotably mounted about a horizontal axis 29 and can be adjusted to a throttling position by means of adjusting elements (not shown) of any design.

In addition, however, there are numerous other embodiments of such throttling partial covers of the Heat exchanger conceivable.

For example, a cover plate could be arranged vertically above the central area of the heat exchanger and by means of an adjusting element, e.g. be adjustable by means of an outwardly directed screw, an adjusting rod or the like, in order to restrict the throughput through the central area of the heat exchanger as required.

FIG. 13 shows the upper part of a combustion chamber 8 of a water heater, in the exhaust gas duct 2 of which a heat exchanger 3 is arranged, into which the water to be heated flows in circulation via the collector 13.

The wall 30 of this combustion chamber 8 and the exhaust gas duct 2 is encased with an insulation 31 in order to prevent heat losses in this area and to allow the heat gained thereby to prevent the accumulation of condensate in the chimney and to increase the temperature of the exhaust gases flowing into the exhaust gas extractor and chimney . On the underside of the heat exchanger 3, that is to say in the upper part of the combustion chamber 8, there is now an insert 32 which covers certain, selectable or adjustable surface area of the heat exchanger 3 from the combustion chamber side by enlarging an upwards towards the heat exchanger 3, has an edge area of this heat exchanger 3 covering width. This insert 32 can be attached flat to the inside of the wall 30 of the exhaust gas duct 2; it consists of a refractory insulating material and thus also contributes to avoidance of heat loss from the exhaust gases. In addition, the wall 30 of the exhaust gas duct 2 can be cooled in this area with a water jacket 33 which is connected via a line 34 to the water circulation of the water to be heated which is conducted via the heat exchanger 3.

This cover could also be constructed in such a way that movably mounted ceramic molded parts cover a variable area of the heat exchanger 3 via an externally accessible adjusting device and, if necessary, reduce the heat-transferring area of this heat exchanger, thereby increasing the exhaust gas temperature in the chimney.

According to the embodiment of the exhaust manifold 4 according to FIG. 14, baffles 35 and 36 are arranged therein, which by their design and arrangement ensure radiation of the heat absorbed by them and reflection of the heat incident on them and thereby increase the exhaust gas temperature.

The baffles 35 extend obliquely upwards against the inlet of the exhaust gas extractor 5, the baffle plate 36 is arranged at a distance from the inlet of the exhaust gas extractor 5 and extends transversely to its axis.

These baffles 35 and 36 achieve a flow within the exhaust gas collector, which favors the absorption of the radiant heat and also ensures a uniform flow through the upstream heat exchanger.

To reduce the temperature of the outside of the exhaust manifold 4, its hood is up to the inlet of the exhaust fume hood covered with an outer shell 37, ie designed with two shells, in order to reduce radiation losses and to ensure high temperatures of the exhaust gas entering the exhaust gas outlet. The inner shell can be designed so that it takes over the function of the above-mentioned guide plates 35.

The required increase in the exhaust gas temperature is also served by a lamella grid shown in FIGS. 15 and 16, that is to say a plate 38 divided into lamellae, which is structured in this way and can be inserted between the exhaust manifold 4 and the heat exchanger 3, and can also be retrofitted if necessary.

Another such structured plate, which consists of a frame 41 and slats 42, is shown in FIGS. 17 and 18.

A structure consisting of such plates 38 and 41 is illustrated in FIGS. 19 and 20 and consists of a displaceably mounted plate 38 and a stationary plate 41. The upper, displaceable plate 38 carries an upwardly projecting edge flange 40. By more or less extensive overlap of the fins 39 and 42, the exhaust gas flow cross-section is adjustable and there are 3 areas within the heat exchanger which are flowed through well or badly. In this way, the active area of the heat exchanger can be reduced, the heat transfer deteriorated and the exhaust gas temperature increased if necessary in order to adapt it to the respectively set or desired nominal heat load.

In addition, by means of such a device a pressure loss-dependent control of the exhaust gas flow from the combustion chamber 8 can be carried out directly into the exhaust manifold 4 by a bypass path 43 of selectable flow cross-section for a measurable proportion of the side of the heat exchanger 3 and the plates 38 and 41 in the exhaust duct 2 Exhaust gases coming into the flue gas outlet are provided, through which this portion reaches the chimney without flowing through the heat exchanger 3. As a result, the pressure loss caused by the articulated plates 38 and 41 is reduced and adaptation to the nominal heat output to be set at the desired exhaust gas temperature in the exhaust gas outlet is made possible.

Claims (33)

1. A burner-heated appliance, particularly water heater, comprising a heat exchanger, which is disposed in a flue gas duct leading from the burner to a chimney or the like flue gas outlet and is flown through by flue gases from that burner, and a combustion chamber, which is disposed below the heat exchanger, characterized in that a by-pass duct by-passing the heat exchanger leads from the combustion chamber (8) directly into the chimney (5) or the like and contains a valve, such as a sliding valve or a throttle flap, for regulating the flow rate of that part of the exhaust gases which are to be supplied directly to the chimney.

2. An appliance according to claim 1, characterized in that the by-pass duct (9) is substantially parallel to the flue gas duct (2) which contains the heat exchanger (3) (Figures 1, 2).

3. An appliance according to claim 2, characterized in that the by-pass duct (9) extends beside the flue gas duct (2) which contains the heat exchanger (3) and leads from the combustion chamber (8) to a common flue gas header (4), from which the chimney (5) or the like flue gas outlet extends (Figures 1, 2).

4. An appliance according to claim 3, characterized in that the by-pass duct (9) is constituted by the components of the heat exchanger (3), e.g., by sections of a multisection boiler (Figure 1).

5. An appliance according to claim 3, characterized in that the by-pass duct (9) is separately provided and at a distance from the flue gas duct (2) which contains the heat exchanger (3) extends from the combustion chamber (8) of the burner (1) to the flue gas header (4) (Figure 2).

6. An appliance according to claim 1 comprising a heat exchanger consisting of a set of finned tubes, characterized in that a portion (15 or 17) of the surface of the heat exchanger has only few or no fins (Figures 3 to 6).

7. A device according to claim 6, characterized in that at least part (16) of the fins (12) in that portion (15) are detachably connected to the tubes (11) (Figures 3, 4).

8. An appliance according to claim 7, characterized in that said fins (16) which are adapted to be detachably connected to the tubes (11) are adapted to be slidably fitted on the tubes (11) and are frictionally joined to said tubes (11) (Figures 3, 4).

9. An appliance according to claim 7 or 8, characterized in that each detachable fin (16) is adapted to be disposed between fixed fins (12) (Figures 3, 4).

10. An appliance according to claim 6, characterized in that the fins (12) comprise wall portions (18), which extend between adjacent tubes (11) and are removable in certain regions (Figures 5, 6).

11. An appliance according to claim 10, characterized in that the fins (12) are formed with punched-out openings (19, 20) to facilitate the separation of the removable wall portions (18) (Figures 5, 6).

12. An appliance according to claim 11, characterized in that the punched openings (19) are arranged in pairs and the two punched openings of each pair extend at an angle to each other for a separation of approximately triangular or trapezoidal wall portions (18) (Figures 5, 6).

13. An appliance according to claim 12, characterized by a transversely extending punched opening (20) formed in the removable wall portion (18) to facilitate the handling thereof (Figure 4).

14. An appliance according to any of claims 10 to 13, characterized in that the fins (12) comprising the removable wall portions (18) are disposed in the heat exchanger (3) in a confined and preferably centrally arranged surface portion (17) of the heat exchanger (3) (Figure 5).

15. An appliance according to claim 1, characterized in that the rate of flow of the flue gases through a portion of the heat exchanger (3) is adapted to be throttled as required (Figures 8 to 12).

16. An appliance according to claim 15 comprising a heat exchanger consisting of a set of finned tubes, characterized in that at least one space (26) confined by such fins (12) which are adjacent to each other is adapted to be defined at least in part by a wall (25) which adjoins at least one of said fins (12) and extends transversely to the plane of said fin (12) (Figures 8 to 10).

17. An appliance according to claim 16, characterized in that said wall (25) extends throughout the space that is defined between two fins (12) disposed adjacent to each other (Figure 10).

18. An appliance according to claim 16, characterized in that said wall (25) extends only over a part of the space defined between fins (12) disposed adjacent to each other (Figures 8, 9).

19. An appliance according to claim 16, characterized in that said wall (25) extends over a plurality of spaces defined each between two fins (12) disposed adjacent to each other (Figure 10).

20. An appliance according to any of claims 16 to 18 comprising fins which at an edge facing to associated heat exchange tube carry a flange (21), which is joined to the tube wall in surface contact therewith, characterized in that the wall (25) which adjoins the outer edge of said fins (12) faces towards that side which is opposite to said flange (21) (Figures 8, 9).

21. An appliance according to any of claims 16 to 20, consisting of a block of heat exchange fins (12), and heat exchange tubes (11) extending through said fins, characterized in that the walls (25) adjoin the fins (12) at the edge portions of said block (Figure 7).

22. An appliance according to any of claims 16 to 21, characterized in that the walls (25) extend in the direction of flow of the flue gases form that edge (22) of the fins (12) which is remote from the combustion chamber (8) (Figure 9).

23. An appliance according to claim 15, characterized by at least one cover plate, preferably a sheet metal plate (27 or 28), which is provided on the heat exchanger (3) or extends over edge portions of the surface of the heat exchanger (3), preferably over mutually opposite edge portions thereof, or over the central portion of said surface (Figures 11, 12).

24. An appliance according to claim 23, characterized in that at least one cover plate (28) is adjustable to a throttling position which is selectable as required, and said cover plate is particularly pivoted on an axis (29) which is parallel to the plane of the heat exchanger (3) (Figure 2).

25. An appliance according to claim 23, characterized in that at least an edge portion of the heat exchanger (3) is covered by at least one insert (32), which is provided on the underside of the heat exchanger in the upper portion of the combustion chamber (8) (Figure 13).

26. An appliance according to claim 25, characterized in that the insert (32) is secured to the preferably cooled and/or insulated wall (30) of the combustion chamber (8) and has a width which increases upwardly towards the heat exchanger (3) and covers an edge portion of the heat exchanger (3) (Figure 13).

27. An appliance according to claim 1, characterized in that guide plates (35, 36) are provided on the upper side of the heat exchanger (3) within a flue gas header (4) and serve to radiate received heat and to reflect incident heat into the flue gas stream (Figure 14).

28. An appliance according to claim 27, characterized by guide plates (35), which rise obliquely towards the inlet of the chimney (5) (Figure 14).

29. An appliance according to claim 27 or 28, characterized by a guide plate (36), which is spaced from the inlet of the chimney (5) and extends transversely to the axis of the chimney (Figure 14).

30. An appliance according to any of claims 27 to 29, characterized by an outer shell (37), which is disposed above the flue gas header (4) and spaced from its outer wall and serves to reduce the radiation of heat from the flue gas header (4).

31. An appliance according to claim 1, characterized by a plate (38), which is divided into fins (39, and/or by a frame (41), provided with fins (42) which plate (38) or frame (41) is adapted to be inserted, preferably slidably inserted, into the flue gas duct (2) and controls the flue gas flow rate through the heat exchanger (3) (Figures 15 to 18).

32.An appliance according to claim 31, characterized in that the plate (38) and the frame (41) are associated with each other and at least one (38) of the two parts (38, 41) is mounted within the flue gas duct (2) to be slidable relative to the other of said parts (Figures 19, 20).

33. An appliance according to claim 31 or 32, characterized in that a by-pass passage for a selectable part of the flue gases flowing through the flue gas duct (2) is provided laterally of the plate or frame (38) which is adapted to be inserted into the flue gas duct and controls the flue gas flow rate and said by-pass passage directly conducts said part of the flue gases into the chimney (5).

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