Abstract:
A cascade unit for a heating system with two or more heating boilers, in particular condensing boilers, with a hydraulic shunt which is connected on the one hand with the inlet flows and return flows of all heating boilers and on the other hand with at least one heating circuit inlet flow and heating circuit return flow each, with the cascade unit furthermore comprising one each of the essentially horizontally extending boiler inlet flow header and boiler return flow manifold, the header and the manifold being connected with the hydraulic shunt, and the header and the manifold each being designed with prepared connecting nozzles fittingly placed for a group of two or more heating boilers for the connection of the heating boiler inlet flows and the heating boiler return flows. The cascade unit forms at least one self-supporting support frame on which at least one of the heating boilers is mountable.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a cascade unit for a heating system with two or more heating boilers, in particular condensing boilers, with a hydraulic shunt which is connected on the one hand with the inlet flows and return flows of all heating boilers and on the other hand with at least one heating circuit inlet flow and heating circuit return flow each, with the cascade unit furthermore comprising one each of the essentially horizontally extending boiler inlet flow header and boiler return flow manifold, the header and the manifold being connected with the hydraulic shunt, and the header and the manifold each being designed with prepared connecting nozzles fittingly placed for a group of two or more heating boilers for the connection of the heating boiler inlet flows and the heating boiler return flows. 
     A cascade unit of the aforementioned type is known from DE 202 11 303 U1. This known cascade unit can be provided with feet placeable on a floor and/or with brackets mountable on a wall or a ceiling. By means of these feet or brackets, the cascade unit can, for itself, be mounted with sufficient stability; however, this known cascade unit is not able to carry the associated boilers because the boilers on the one hand and the cascade unit on the other hand are connected with each other only via the boiler inlet flow connections and the boiler return flow connections. The boiler inlet flow connections and the boiler return flow connections are, however, not suitable for taking up the great weight of the boilers. It has thus been required, until now, to install the boilers by themselves, with a hanging installation on a wall or on a ceiling of a heating room usually being provided with modern boilers. Usually, frames or brackets are first mounted on the wall or the ceiling for that on which the boilers will then be mounted in suspension. 
     With this known state of the art, it is considered disadvantageous that, for the heating installation, major assembly expenditures are required on location in the heating room and that, additionally, very precise workmanship is absolutely required so that the heating boilers on the one hand provided on the wall or on the ceiling and the cascade unit also mounted in the heating room with its own feet or brackets will be positioned correctly to each other. Experience has shown that this presents a source of errors, resulting in frequently expensive adjustment work or modifications being required when the cascade unit is hydraulically connected with the boilers. 
     SUMMARY OF THE INVENTION 
     For this invention, the problem accordingly presents itself of creating a cascade unit of the initially mentioned type which avoids the presented disadvantages and which achieves, in particular, a significant reduction of the assembly expenditure in the installation of a heating system and which enables an extensive and thus cost-saving prefabrication as well as a smooth transport. 
     In accordance with the invention, this problem is solved with a cascade unit of the initially mentioned type which is characterized in that it forms at least one self-supporting support frame on which at least one of the heating boilers (each) is mountable. 
     With the cascade unit according to the invention, this cascade unit itself advantageously forms a support frame serving for the attachment of one or several heating boilers, thus a separate mounting of the heating boilers on a wall or the ceiling of the heating room no longer being required. Moreover, the cascade unit according to the invention offers the advantage that the associated boilers can be already assembled and prefabricated together with the cascade unit and subsequently transported to the place of installation of the heating system. Thus, prefabrication will be possible in a clean production building which offers adequate space and all the required auxiliaries. On location in the heating room of the heating system, the cascade unit including the boilers need then only be connected at very few points with a heating network, a fuel feed line, a waste gas line and with electrical lines which will advantageously keep the installation expenditure at the place of installation very low and largely excludes installation errors. 
     To be able to meet several functions each with one component within the cascade unit, header and manifold preferably are bearing elements of the self-supporting support frame. 
     In a further development, it is preferably provided that the header and the manifold are arranged at a distance to each other in a vertical plane and that vertical pipe sections are provided between the header and the manifold, with the pipe sections being hydraulically connected either with the header or with the manifold and carrying water at least over partial sections of their length and comprising connecting nozzles for the connection of the heating boiler inlet flows and the heating boiler return flows. This embodiment of the cascade unit provides a design of relatively great height and relatively small depth. 
     In an alternative embodiment thereto, it is provided that the header and the manifold are arranged in a horizontal plane at a distance to each other and that horizontal pipe sections are provided between the header and the manifold, with the pipe sections being hydraulically connected either with the header or with the manifold and carrying water at least over partial sections of their length and comprising or bearing the connecting nozzles for the connection of the heating boiler inlet flows and the heating boiler return flows. This embodiment of the cascade unit offers a design of relatively low height and greater depth. In both above specified embodiments, a particularly high degree of integration of the different functions with few individual parts will be achieved which is very advantageous not only in terms of the technical side of manufacturing but also with regard to the material expenditure and the manufacturing costs. 
     Furthermore, it is preferably provided that the header, the manifold and the vertical or horizontal pipe sections are designed as hydraulically and statically adequately dimensioned round or square steel pipes. In the embodiment here specified, the header, the manifold and the vertical or horizontal pipe sections can be designed with high strength and carrying capacity and can moreover be welded with each other without any problems, without any particularly high material costs being incurred or any particularly difficult processing being required. 
     To be able to hydraulically couple the hydraulic shunt forming one part of the cascade unit as advantageously as possible and without detours with the header and the manifold, it is proposed that the header and the manifold are each connected on their one lateral face end with the essentially vertically oriented hydraulic shunt, with the header connecting to the shunt on the top and the manifold on the bottom. 
     A further development of the cascade unit provides that the hydraulic shunt is firmly connected with the header and the manifold and forms a bearing element of the self-supporting support frame. In this embodiment, the hydraulic shunt also assumes a bearing function within the support frame. Expediently, the hydraulic shunt here consists of a housing of steel, preferably with a rectangular cross section so that, here too, a solid and durable welding connection of the header and the manifold with the housing of the hydraulic shunt will be possible without any problem. 
     Alternatively, the hydraulic shunt can be detachably connected with the header and the manifold and form a non-bearing element or a bearing element of the self-supporting support frame. This embodiment of the cascade unit will be expedient in particular when it is to be used in different applications once with the hydraulic shunt and once without the hydraulic shunt. 
     To be able to adjust the cascade unit according to the invention as simply as possible to the different requirements in terms of the heat output, one embodiment of the invention proposes that the cascade unit comprises several self-supporting support frames which are each mechanically and hydraulically detachably connected in the area of the face ends of the header and the manifold. In this embodiment of the cascade unit, the support frames are forming a module system, wherein with one or several basic types of the support frame differently sized cascade units are fast and easily realizable with different numbers of heating boilers. Due to the connection of the respectively abutting face ends of the headers and manifolds of two adjacent support frames each, they will be mechanically as well as hydraulically connected with each other in one operation which keeps the installation expenditure advantageously low. 
     To ensure an unrestricted application of the cascade unit, the header and the manifold are each expediently formed on one or on both face ends with one standardized connecting means each, preferably a connecting flange. 
     Another measure which serves to keep the installation expenditure low consists of the/each support frame preferably comprising prepared boiler mounting elements adjusted to the boilers to be mounted. Thus, the possibility exists to adjust through a simple replacement of the boiler mounting elements the cascade unit to differently sized heating boilers or to boilers of different manufacturers. 
     Since a heating system comprises aside from the heating boilers, the header and the manifold and the hydraulic shunt still other components, another embodiment of the cascade unit proposes that the support frame comprises mounting elements and/or connections for other components of the cascade unit, in particular for expansion vessels, vent fittings, sensors, control devices and other fittings and/or functional elements. 
     An additional step in the direction of the most extensive prefabrication of the cascade unit consists of a line section with suitably positioned branches to all mounted boilers being arranged on the support frame for the supply of gaseous or liquid fuel. Advantageously, in this embodiment of the cascade unit, the line section for the fuel must only be connected at a single interface with a line section supplying the fuel into the heating room; all other connections and branches within the cascade unit for the distribution of the fuel to the boilers can be manufactured already in advance and checked for their tightness. 
     For the same objective, it is proposed that, on the support frame, one line section (each) is arranged with suitably positioned line branches from all mounted boilers for the collection and removal of waste gases and/or the collection and removal of condensate. 
     To be able to transport and move the cascade unit as easily as possible before its final installation, several casters can be provided on the underside of the support frame. With these casters, the cascade unit can be moved by muscle power alone which, in many application cases, will render unnecessary the expensive use of hoisting or transporting equipment. 
     Since the casters are no longer required after the final installation of the cascade unit in the heating room, one embodiment proposes that the casters are detachably mounted on the support frame and can be replaced by floor or wall brackets. 
     Another advantageous embodiment proposes that the header and the manifold are arranged in a horizontal plane at a distance to each other and that pipe sections extend vertically from the header and the manifold to the boiler, with the pipe sections being mechanically and hydraulically connected with the respectively allocated header or manifold and with the pipe sections having connecting nozzles for connection to the boiler. With this advantageous embodiment, the hydraulic shunt is preferably hydraulically and mechanically connected with the manifold. 
     Thus, for the connection of the header with the hydraulic shunt, a bypass is advantageously provided comprising a horizontal line section and a vertical line section. The bypass here extends with its horizontal line section from the header towards the manifold and passes to the vertical line section which is connected at an upper end of the hydraulic shunt with it, so that the header is hydraulically connected with the hydraulic shunt. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Additional advantageous embodiments of the invention are disclosed in the sub-claims and the following description of the figures. It is shown: 
         FIG. 1  is a cascade unit in a first embodiment, in a front view; 
         FIG. 2  is the cascade unit of  FIG. 1  in a side view; 
         FIG. 3  is the cascade unit in a second embodiment in a front view; 
         FIG. 4  is the cascade unit of  FIG. 3  in a top view; 
         FIG. 5  is the cascade unit of  FIGS. 3 and 4  in a side view; 
         FIG. 6  is the cascade unit in an additional, modular embodiment in a front view, before assembly; 
         FIG. 7  is the modular cascade unit of  FIG. 6  in a front view, in assembled condition; 
         FIG. 8  is the cascade unit in an additional embodiment in a front view; 
         FIG. 9  is the cascade unit of  FIG. 8  in a top view; 
         FIG. 10  is the cascade unit of  FIGS. 8 and 9  in a side view; 
         FIG. 11  is the cascade unit of  FIG. 8  in a front view without a boiler; 
         FIG. 12  is the cascade unit of  FIG. 11  in a top view; 
         FIG. 13  is the cascade unit of  FIGS. 11 and 12  in a side view; 
         FIG. 14  is the cascade unit of  FIG. 8  as a section with the hydraulic shunt as a detail in a front view; and 
         FIG. 15  is the cascade unit of  FIG. 8  in a side view. 
     
    
    
     In the different figures, same parts are always provided with the same reference numbers so that, as a rule, they will also be described only once. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the example of the cascade unit  1  according to  FIG. 1 , it is designed for taking up two heating boilers  2 . For this, the cascade unit  1  comprises on the top a horizontally extending boiler inlet flow header  3  and at a vertical distance thereunder an also horizontally extending boiler return flow manifold  4 . In a vertical direction, the header  3  and the manifold  4  are mechanically connected with each other through vertical pipe sections  63  and  64 . Here, alternately, a vertical pipe section  63  is hydraulically connected with the header  3  and a pipe section  64  with the manifold  4 . That means that the pipe sections  63  are impervious to liquids at their bottom end and are here only mechanically connected with the manifold  4 , not however hydraulically. Correspondingly, the vertical pipe sections  64  are connected at their upper end only mechanically with the header  3 , not however hydraulically. 
     At their right face end in  FIG. 1 , the header  3  and the manifold  4  are connected mechanically as well as hydraulically with a vertically aligned shunt  5 . On its side showing to the right in  FIG. 1  and facing away from the header  3  and the manifold  4 , the hydraulic shunt  5  comprises on the top a heating circuit inlet flow connection  55  and on the bottom a heating circuit return flow connection  56 . A heating circuit can be connected to these connections  55 ,  56  which is here purely schematically combined with a symbolically presented pump  53  and an also symbolically presented heating system  54 . 
     The header  3 , the manifold  4 , the vertical pipe sections  63  and  64  and the hydraulic shunt  5  here form a solid, self-supporting support frame  10  which is capable of carrying the heating boilers  2 , without the heating boilers  2  having to be held via other fastening elements on a wall or another building part or on separate carriers. 
     The supply of the water flowing through the cascade unit  1  and the heating circuit, serving as the heat transport medium to the individual boilers  2  and the delivery of the heated water from the boilers  2  into the heating circuit is here effected via the connecting nozzles  32  and  42 , respectively. One connecting nozzle  32  each is here allocated to each vertical pipe section  63 , and one connecting nozzle  42  each to each vertical pipe section  64 , not only mechanically but also hydraulically. To take up the weight of the heating boilers  2 , the support frame  10  is provided with boiler mounting elements here not shown which are designed to fit with the size and type of the boiler  2  to be respectively mounted and which are positioned within the support frame  10 . 
     Below the manifold  4 , two crossbars  11  are provided which carry a total of four casters  13  on the underside. By means of these casters  13 , the complete cascade unit  1  including the boilers  2  can be moved in a rolling manner by muscle power, without the use of hoisting or transport equipment. After the cascade unit  1  has been brought to its place of installation, the casters  13  can be separated from the support frame  10  and replaced by fixed floor or wall brackets. 
     Additionally, the cascade unit  1  in the example presented in  FIG. 1  also comprises several vent fittings  72  to be able to automatically or manually vent the header  3 , the manifold  4  and the hydraulic shunt  5 . A sensor  73  is provided on the upper side of the hydraulic shunt  5 , for example a thermometer provided in a dip sleeve. Finally, on the lower end of the hydraulic shunt  5 , on the part of the cascade unit  1  which is lowest and flowed through b&gt;water, a drainage nozzle  75  is provided via which the cascade unit  1  can be drained as needed. Moreover, the nozzle  75  can be used for the removal of sludge which settles in the lower part of the hydraulic shunt  5 . 
       FIG. 2  now shows the cascade unit  1  of  FIG. 1  in a side view onto the left side in  FIG. 1 . Here, the compact construction of the cascade unit  1  and the support frame  10  will be especially obvious, with the heating boilers  2  not being drawn into  FIG. 2 . 
     In  FIG. 2 , the front ends of the boiler inlet flow header  3  and the boiler return flow manifold  4  are facing the viewer. The pipe section  63  extends vertically between them; additional pipe sections  63  and  64  (compare  FIG. 1 ) are provided hidden behind it. All the way in the back of  FIG. 2 , the hydraulic shunt  5  is provided which has a greater depth than the vertical pipe sections  63  and  64 . 
     From the lower area of the visible vertical pipe section  63 , the connecting nozzle  32  extends towards the front and the top through which the water to be heated can be supplied to the heating boiler. The other connecting nozzles  32  and the connecting nozzles  42  (compare  FIG. 1 ) are hidden behind it in  FIG. 2 . 
     Behind the hydraulic shunt  5 , the heating circuit inlet flow connection  55  is provided on the top and the heating circuit return flow connection  56  on the bottom, each in the form of a round connecting flange. 
     In the lower area of the support frame  10 , one of the crossbars  11  extends horizontally; the second crossbar  11  is provided hidden behind it. On the underside, the crossbars  11  are provided with casters  13 , two of which are visible in  FIG. 2 . 
     All the way on top in  FIG. 2 , the two vent fittings  72  are still visible which rest on the upper side of the header  3  and on the upper side of the hydraulic shunt  5 . 
       FIG. 3  shows an example of the cascade unit  1  in which other components of a heating system are provided on the support frame  10  in addition to two heating boilers  2 . The self-supporting support frame  10  is formed, here again, by the boiler inlet flow header  3  extending horizontally on the top, in parallel therewith the boiler return flow manifold  4  extending horizontally on the bottom, the vertically extending pipe sections  63  and  64  arranged between them, and the hydraulic shunt  5 . To obtain a solid construction, the indicated parts are expediently rectangular steel profiles or pipes and welded with each other. The two heating boilers  2  are each respectively hydraulically connected via one of the connecting nozzles  32  with the header  3  and one of the connecting nozzles  42  with the manifold  4 . The largest part of the vertical pipe sections  63  and  64  lies here respectively hidden behind the two heating boilers  2 . 
     On the right side next to the right boiler  2  in  FIG. 3 , two control devices  74  are mounted one on top of the other on the top of the support frame  10 , with one control device  74  each being respectively allocated to one of the heating boilers  2 . Behind the lower control device  74 , an expansion vessel  71  is provided, partially hidden by it, which is hydraulically connected with the manifold  4 . Other components, here forming one part of the cascade unit  1 , are several vent fittings  72  on the header  3 , the manifold  4  and the hydraulic shunt  5 , a sensor  73  on the upper side of the hydraulic shunt  5  and a drainage nozzle  75  on the underside of the hydraulic shunt  5 . Additionally, one pressure switch  76  each is here also provided on header  3  and manifold  4 . 
     On the right side in  FIG. 3 , the hydraulic shunt  5  again comprises on the top the heating circuit inlet flow connection  55  and on the bottom the heating circuit return flow connection  56  for combining the cascade unit  1  with a heating circuit. 
     In the lower part of the support frame  10 , again two crossbars  11  are arranged below the manifold  4  which are provided with a total of four casters  13  on the underside. Here again, the complete cascade unit  1  can be moved by means of the casters  13  without hoisting and transport equipment to transport the unit to a place of installation. 
       FIG. 4  shows the cascade unit  1  of  FIG. 3  in a top view. On the top in  FIG. 4 , the header  3  is now provided and underneath, hidden, the manifold  4  which are both connected with each other by the vertical pipe sections  63  and  64  here also hidden and thus presented in a broken line. 
     On the bottom in  FIG. 4 , the two boilers  2  can be seen in a top view which are each hydraulically connected with the header  3  and the manifold  4  via the connecting nozzles  32  and  42 . Moreover, the boilers  2  are mechanically connected with the support frame  10  via the boiler mounting elements  12 . In this fashion, the support frame  10  takes over the entire load which the heating boilers  2  present, so that here as well, the heating boilers  2  are exclusively mounted in suspension on the support frame  10 . 
     The expansion vessel  71  is provided on the right next to the right heating boiler  2  in  FIG. 4 . The control devices  74  are placed in front, easily accessible for an operating person. All the way in the background of  FIG. 4 , the lower crossbars  11  are now provided with the casters here not visible. 
     The hydraulic shunt  5  is visible on the top right in  FIG. 4  in connection to the right face end of header  3  and manifold  4 , in a top view. Towards the right, the heating circuit inlet flow connection  55  extends from the hydraulic shunt  5 ; the heating circuit return flow connection is provided hidden thereunder. 
     All the way on the left, the vent fitting  72  is visible on the upper side of the header  3 . On the upper side of the header  3 , the sensor  73  is provided on its right end area. The pressure switch  76  is provided to the left next to it. 
       FIG. 5  shows the cascade unit  1  from  FIGS. 3 and 4  in a lateral view on the left side. To the left in  FIG. 5 , the header  3  is visible on the top and the manifold  4  on the bottom in the front view. Vertically connected are the header  3  and the manifold  4  via the hydraulic shunt  5  lying in the background, and the vertical pipe sections of which only the front pipe section  63  is here visible. 
     From the visible pipe section  63 , the connecting nozzle  32  extends toward the front and the top, the nozzle being connected with the associated boiler  2 . The other connecting nozzle  32  and the other connecting nozzles  42  (compare  FIGS. 3 and 4 ) hydraulically connected with the manifold are hidden in  FIG. 5  and thus are not visible. 
     Behind the heating boiler  2  visible in  FIG. 5 , the second heating boiler  2  is provided; the expansion vessel  71  is provided behind it again. 
     On the bottom of  FIG. 5 , one of the two crossbars  11  with two of the casters  13  is again visible. 
     Finally, on the left in the background of  FIG. 5 , the heating circuit inlet flow connection  55  and the heating circuit return flow connection  56  are partially still visible in the form of the round connecting flanges. 
       FIGS. 6 and 7  show a modularly structured cascade unit  1 .  FIG. 6  shows the two support frames  10  and the associated hydraulic shunt  5  as not yet connected components. This allows a separate transport, with the individual support frames  10  still being easy to transport and to handle when a large heating system is to be installed with more than two or three heating boilers  2 . At the place of installation, the two (or even more) support frames  10  and the hydraulic shunt  5  are each mechanically as well as hydraulically coupled with each other, with the completed cascade unit  1  then forming, as seen in  FIG. 7 . 
     In the example according to  FIGS. 6 and 7  as well, the support frame  10  is formed each by a boiler inlet flow header  3 , a boiler return flow manifold  4  and several pairs of vertical pipe sections  63  and  64 . In the example shown here, the support frame  10 , respectively presented on the left, comprises three pairs of vertical pipe sections  63  and  64  and is thus designed to take up three heating boilers  2 . The support frame  10 , respectively presented on the right, comprises two pairs of vertical pipe sections  63  and  64  and is thus designed to take up two heating boilers  2 . 
     The header  3  and the manifold  4  of the left support frame each comprise on their right front face one connecting flange  31  and, respectively,  41  each. For the right support frame  10 , not only the header  3  but also the manifold  4  are provided, on their two front faces, with matching, identical flanges  31  and  41 , respectively. The hydraulic shunt  5  comprises—on its left side facing the right support frame  10  at a suitable distance two connecting flanges  51  which are connectable with the right connecting flanges  31  and  41 , respectively of the right support frame  10 . 
     Solely via the connecting flanges  31 ,  41  and  51 , the two support frames  10  and the hydraulic shunt  5  are not only connected with each other mechanically sufficiently solidly, but also hydraulically in a manner impervious to liquids.  FIG. 7  reflects the completely connected condition. The integrally designed support frames  10 , here again, carry all boilers  2 . 
     Another exemplary embodiment of the cascade unit  1  is presented in  FIGS. 8 to 15 . In contrast to  FIGS. 1 to 7 , the embodiment according to  FIGS. 8 to 15  comprises boiler inlet flow header  3  and boiler return flow manifold  4  which are horizontally spaced to each other. As before, the boiler inlet flow header  3  and the boiler return flow manifold  4  each extend in a horizontal direction. The boilers  2  are standing on the header  3  and the manifold  4  which will be elaborated on further below. 
     In the selected presentation, the boiler inlet flow header  3  is in the foreground, with the boiler return flow manifold  4  being hidden by it in the background. Accordingly, only the pipe sections  63  are visible, with the pipe sections  64  hidden by them. The pipe sections  63  and  64 , respectively, extend vertically from the header  3  or, respectively, from the manifold  4  to the boiler  2  and are hydraulically and mechanically connected on the one hand with the header  3  and, respectively, the manifold  4  and on the other hand with the boiler  2  via the connecting nozzles  32  and  42 , respectively. In contrast to the exemplary embodiments according to  FIGS. 1 to 7 , the corresponding pipe sections  63  and  64 , respectively, comprise no mechanical connection to the respectively not allocated header  3  and manifold  4 , respectively. 
     On their right face end in  FIG. 8 , the header  3  and the manifold  4  are connected with the vertically aligned hydraulic shunt  5 . At the right side of the drawing, the manifold  4  opens directly into the hydraulic shunt  5  for which suitable connecting means can be used. The manifold  4  is hydraulically and mechanically connected with the hydraulic shunt  5 . 
     The header  3  is allocated to a bypass  630  which comprises two line sections  631  and  632 . The line section  631  extends in horizontal direction from the header  3  towards the manifold  4  and passes over into a vertical line section  632  which is connected with the hydraulic shunt  5  in its upper end area. The vertical line section  632  extends parallel to the hydraulic shunt  5 . The horizontal line section  631  is hydraulically and mechanically connected with the header  3 , and a mechanical connection with the manifold  4  can be chosen for supporting the end of the horizontal line section  631  pointing to the manifold  4 . Thus, the header  3  is hydraulically connected with the hydraulic shunt  5 . 
     In the exemplary embodiment presented, three crossbars  11  are provided below the header  3  and the manifold  4 . The crossbars  11  extend in a horizontal direction and are each provided on the underside with two casters  13  each, of which one each is respectively hidden in  FIG. 8 . 
     By means of these casters  13 , the complete cascade unit  1  including the boilers  2  can be moved in a rolling mariner by muscle power, without the use of hoisting or transport equipment. After the cascade unit  1  has been brought to its place of installation, the casters  13  can be separated from the support frame  10  and replaced by fixed floor or wall brackets. 
     In the presented exemplary embodiment, two boilers  2  are allocated to the cascade unit  1  which are held on boiler mounting elements  12 . In longitudinal direction of the cascade unit  1 , the boilers  2  are spaced from each other and connected to a gas line  82  by means of suitable connections  81 . In the presented exemplary embodiment, the gas line  82  extends above the cascade unit  1 . 
     The boiler mounting elements  12  are designed as U-shaped brackets which rest or, respectively, are connected with their basic leg in a longitudinal direction on the allocated header  3  or manifold  4 , respectively ( FIG. 9 ). From the basic segment, U-bars of the mounting element  12  extend from the respectively allocated header  3  or manifold  4 , respectively, vertically towards the top. The mounting elements  12  are somewhat wider than the boiler  2  so that the U-bars are spaced to the respectively allocated boiler  2  in the longitudinal direction of the cascade unit  1 . In the presented exemplary embodiment, two separate mounting elements  12  each are used for one boiler  2  which are spaced to each other in accordance with the horizontal distance of the header  3  to the manifold  4 , minus a lateral projection over the header  3  or the manifold  4 , respectively. Of course, a one-piece mounting element  12  could also be used for every boiler  2 , such element spanning the free space between the header  3  and the manifold  4  and each somewhat laterally projecting from the header  3  or the manifold  4 , respectively. 
     Additionally, the cascade unit  1  in the example presented in  FIG. 8  can also comprise several vent fittings  72  to be able to automatically or manually vent the header  3 , the manifold  4  and the hydraulic shunt  5 . The sensor  73  is provided on the upper side of the hydraulic shunt  5 , for example a thermometer provided in the dip sleeve. Finally, on the lower end of the hydraulic shunt  5 , on the part of the cascade unit  1  which is lowest and flowed through by water, the drainage nozzle  75  is provided via which the cascade unit  1  can be drained as needed. Moreover, the nozzle  75  can be used for the removal of sludge which settles in the lower part of the hydraulic shunt  5 . 
       FIG. 9  shows the cascade unit  1  of  FIG. 8  in a top view. Clearly evident are the horizontally spaced header  3  and manifold  4 , as well as the crossbars  11  arranged thereunder. Moreover, the boilers  2  are mechanically connected with the support frame  10  via the boiler mounting elements  12 , with the corresponding mounting elements  12  laterally projecting somewhat from the header  3  or the manifold  4 , respectively, which is presented by the broken line. The boilers  2  are arranged advantageously upright, standing on the cascade unit  1 . The hydraulic shunt  5  is visible on the top right in  FIG. 9  following the right face end of manifold  4  in a top view. The course of the horizontal line section  631  from the header  3  in the direction towards the manifold  4  is also visible. Towards the right, the heating circuit inlet flow connection  55  extends from the hydraulic shunt  5 ; the heating circuit return flow connection is provided hidden thereunder. 
       FIG. 10  shows the cascade unit  1  from  FIGS. 8 and 9  in a side view, thus onto a side wall of the hindmost boiler  2  seen in the longitudinal direction of the cascade unit  1 , relative to the hydraulic shunt  5 . A waste gas connection  83  of the boiler  2  is visible in  FIGS. 9 and 10 . Furthermore, the pipe sections  63  and  64 , respectively, are visible in  FIG. 10 , with the pipe section  63  or, respectively, the inlet flow connection of the boiler  2  being allocated to the header  3 , relative to a center axis X on the right side, and the pipe section  64  or, respectively, the return flow connection of the boiler  2  being allocated to the manifold  4  on the left side opposite thereto. Moreover, one of the crossbars  11  is visible, hiding the other crossbars. From the header  3 , the horizontal line section  631  is extended towards the manifold  4 . The vertical line section  632  is not presented in  FIG. 10 . The hydraulic shunt  5  is presented in a broken line since it is provided, in the selected view, hidden in the background by the boiler or boilers  2 . Underneath the horizontal line section  631  or, respectively, the manifold  4 , the heating circuit return flow connection  56  is visible, with the heating circuit inlet flow connection  55  being covered and therefore presented in a broken line. 
     In  FIG. 11 , the cascade unit  1  is presented without the installed boilers  2 , with the gas line  82  also being cut away. However, the vent fitting  72 , the sensor  73  and the bottom arranged drainage nozzle  75  of the hydraulic shunt  5  can be taken exemplarily from  FIG. 11 . Furthermore, the connection of the heating circuit with the optional pump  53  is principally shown and the exemplary heating system  54  to the connections  55  and  56 . 
     In  FIG. 12 , which is principally equivalent to  FIG. 9 , only without boiler  2 , the flow of the heating water is exemplarily presented by means of the arrows  84  in the header  3 , the manifold  4  and the bypass  630 , in particular in its horizontal line section  631 . 
       FIG. 13  presents the cascade unit  1  in a side view, with the flow of the water being shown by means of the arrows  84  in the piping sections  63  and  64 , respectively, and through the boiler. Relative to the piping section  64 , the hydraulic shunt  5  is provided behind it, with the piping section  64  being somewhat narrower than the hydraulic shunt  5 . The piping section  63  arranged on the right laterally thereto preferably has the same dimension as the piping section  64 . The flow of the water from the manifold  4  via the piping section  64  through the boiler  2  via the piping section  63  into the header  3  is, in turn, exemplarily presented by means of the arrows  84 . 
     In  FIG. 14 , one part of the cascade unit  1  with the hydraulic shunt  5  is shown enlarged in a front view, with  FIG. 15  showing a side view to  FIG. 14 . 
     The manifold  4  opens directly into the hydraulic shunt  5 , with the horizontal pipe section  631  being provided above the manifold  4  and being presented supporting itself on the manifold  4 . The horizontal line section  631  can here be connected with the manifold  4 , for example in a positive material connection, preferably welded. The vertical line section  632  extents vertically to the horizontal line section  631  in the direction of the upper end area of the hydraulic shunt  5  and opens into it. The vertical line section  632  can be connected or, respectively, mounted to the hydraulic shunt in a suitable manner to secure the position. 
       FIG. 15  presents exemplarily, by means of the arrows  84 , the flow of the water from the header  3  through the bypass  630  with its two line sections  631  and  632  into the hydraulic shunt  5 , with a flow connection from the vertical line section  632  into the hydraulic shunt  5  being exemplarily shown by means of the recess  86 , presented in a broken line. The vertical line section  632  is somewhat narrower than the hydraulic shunt  5 . 
     As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.