EP1384954B1 - Cascaded arrangement for a heating installation with two or more boilers - Google Patents

Abstract

The cascade unit (1) for a heater has a hydraulic arm (5) which on one side moves toward or away from the heating kettle and on the other side is connected to at least one heating inlet (55) and heating system return (56). The cascade unit has a horizontally running chamber collector (3) and distributor (4) which is fixably connected to the hydraulic arm and connecting supports (33,44,33',44') in the form of short, horizontal pipes.

Description

The present invention relates to a cascade unit for a heating system with two or more boilers, in particular with hanging mounted condensing boilers, with a hydraulic switch, which is connected on the one hand to the heats and return of all boilers and on the other hand with at least one each heating circuit and heating circuit return, wherein the cascade unit Furthermore, each comprises a substantially horizontally extending boiler flow collector and boiler return manifold, wherein the collector and the manifold are arranged directly above one another and fixedly connected to the hydraulic switch and form with this the prefabricated, a portable construction and assembly unit performing cascade unit, and wherein the collector and the manifold are each made with prepared, adapted for a group of two or more boilers fitting connection for connecting the boiler precursors and the boiler returns are executed.

A cascade unit of the type mentioned is out EP-A-1 036 993 known as part of a cascade heating system. In the known cascade unit is provided that the connecting piece in the form of upwardly facing straight pipe sections and / or in the form of initially horizontal, preferably run to the rear, and then upwardly extending pipe bends and are firmly attached.

The version with the upwardly pointing connecting pieces has proved in practice to be less suitable, because it is expedient, the collector and the manifold and the hydraulic switch, which together form the cascade unit, at a sufficient distance from a wall of a boiler room to arrange on the boilers are usually mounted hanging. This distance is required to have access to the back of the cascade unit in order to carry out work there. In practice, therefore, essentially only the version of the known cascade unit was used, in which the connection piece in the form of initially horizontal and then upwardly extending pipe bends are executed.

A disadvantage has been found in this known cascade unit that it has a relatively large width or depth due to the running in the form of pipe bends connecting piece, which complicates the storage and transport of the cascade unit. In particular, a relatively large storage and transport space is needed. The "bulkiness" of the cascade unit is essentially caused by the far projecting pipe socket. In addition, these protruding pipe sockets are subject in particular during transport of the risk that they are bent and damaged by external influences. As a result, at least subsequent straightening work is required; in the worst case, it can even lead to leaks at the connection of the pipe socket to the collector or distributor, which also additional welding to restore the tightness are required.

Another disadvantage is seen in the fact that two different versions must be made in the known cascade unit, if either the hydraulic switch should be positioned on the left or right of the collector and distributor. This represents a high manufacturing and storage costs and causes a risk of incorrect ordering by customers or wrong delivery by the manufacturer.

The document GB 1 333 691 A shows a manifold-collector unit without hydraulic switch. The document deals with the problem to keep the production of this unit by welding as simple as possible. In the FIGS. 4 and Figure 5 of this document shows an embodiment in which the collector and manifold are directly superimposed and the ports extend fore and aft. In each case, a flow connection, which goes off to the rear, in congruent position, a flow connection, which goes to the front, opposite and according to each return port, which is located on the back, in congruent position opposite a return port on the front. So there are both the front side and the back side in the longitudinal direction congruent positions provided the connecting piece.

Disadvantageously, the unit according to this document during installation must have a certain orientation, because they, as well as the cascade unit according to the first document of the prior art, is usable only in a certain mounting position. If you follow the unit according to FIG. 4 of the second document about a vertical, that is perpendicular to the plane of the drawing FIG. 4 rotating axis of rotation would come to the place of in FIG. 4 first lying on the top left feed port 17 of the first lower right return port 18 and it would thus lead to incorrect connections in the outgoing and incoming lines. For different mounting positions so also different versions of the unit must be made here.

For the present invention, therefore, the task of creating a cascade unit of the type mentioned, which avoids the disadvantages set out and in particular a reduced manufacturing and assembly costs are achieved, are simplified in the storage and transport, the less susceptible to damage in their Transport is and allows a more flexible creation of the heating system.

• daß die Anschlußstutzen in Form von kurzen, horizontal verlaufenden geraden Rohrabschnitten ausgeführt sind,
• daß an jedem Anschlußstutzen entweder ein in Richtung zum jeweiligen Heizkessel laufender Rohrbogen oder ein Blindstopfen anbringbar ist,
• daß in Längsrichtung von Sammler und Verteiler gesehen die Anschlußstutzen jeweils abwechselnd vorderseitig und rückseitig am Sammler und am Verteiler angeordnet sind,
• daß jeweils ein Anschlußstutzen des Sammlers und ein Anschlußstutzen des Verteilers ein gleich weit von der hydraulischen Weiche entferntes Paar von zwei zueinander entgegengesetzt ausgerichteten Anschlußstutzen bilden und
• daß nach einer Drehung der Kaskadeneinheit um eine vertikale Achse um 180° eine von links nach rechts oder von rechts nach links geänderte Lage der hydraulischen Weiche relativ zu Sammler und Verteiler, jedoch eine mit der vorherigen Anordnung identische Anordnung aller Anschlußstutzen vorliegt.

The solution of the problem is achieved according to the invention with a cascade unit of the type mentioned, which is characterized

• that the connecting pieces are designed in the form of short, horizontally extending straight pipe sections,
• that either a pipe bend running in the direction of the respective boiler or a blanking plug can be attached to each connecting piece,
• that seen in the longitudinal direction of the collector and manifold, the connecting pieces are arranged alternately on the front side and on the back side of the collector and on the distributor,
• that in each case a connecting piece of the collector and a connection piece of the distributor form an equidistant from the hydraulic switch remote pair of two mutually oppositely oriented connecting pieces and
• that after a rotation of the cascade unit about a vertical axis by 180 ° one from left to right or from right to left changed position of the hydraulic switch relative to collector and distributor, but an identical arrangement with the previous arrangement of all connecting pieces is present.

Advantageously, the cascade unit according to the invention in comparison to the known from the prior art cascade unit has a much more compact design, in particular a much smaller depth, as now dispensed with the far-projecting pipe bends as parts of the prefabricated cascade unit. That's why to store and transport the cascade unit much more space-saving. In addition, the short pipe sockets are much less sensitive to possible bending or damage during storage and transport. Another important advantage of the cascade unit according to the invention is that only one embodiment of the cascade unit must be made by the alternately front and rear arrangement of the connecting piece, which can then be installed optionally with a left or right positioned hydraulic switch in a heating system. To change the positioning of the hydraulic switch only the cascade unit must be rotated about its vertical axis by 180 °; other changes are not necessary. Thus, a significant rationalization in the manufacture of the cascade unit is achieved because it was necessary in the cascade unit according to the prior art to produce two different versions for an arrangement of the hydraulic switch on the left and for an arrangement of the hydraulic switch on the right side , Another advantage that is achieved with this is that it can be determined on site at the construction site, whether the hydraulic switch should be positioned on the right or left of the collector and distributor; this allows greater flexibility in the creation of the heating system and avoids wrong orders or wrong deliveries and thereby caused time delays. The required pipe bends, over which the short connecting pieces are to be connected to the respective associated boilers, are simply supplied as loose parts in the required number and connected on site at the construction site with the required connection piece. The connecting pieces, which are not needed in each case, are simply closed with suitable blind plugs.

In a further embodiment of the invention, it is provided that the connecting pieces are formed with flat-sealing connection nipples. With this design is achieved in particular that the connections between the boilers on the one hand and collectors and manifolds on the other hand can be made in a simple manner, since a nesting of pipe sections with the need to temporarily increase distances between the parts to be connected, is eliminated.

In order to manufacture collectors and distributors as simple as possible and at the same time to achieve a high intrinsic stability, the collector and the distributor are preferably designed as stacked rectangular tubes, preferably with a common center wall. If a common center wall is used, even a material-saving construction is achieved. For the production of collectors and distributors then a rectangular tube with a parallel U-profile can be welded longitudinally, whereby the desired two superimposed rectangular tubes can be realized.

Further, the invention proposes that the collector is at the top and the distributor at the bottom and that the collector and distributor are mechanically fixed at their one end face to the substantially vertically oriented hydraulic separator near its lower end. The hydraulic switch can not be placed below the boiler due to their height usually. Therefore, the proposed connection between collector and manifold on the one hand and hydraulic switch on the other hand particularly useful, since in this case the hydraulic switch positioned on the left or right of the boiler row becomes. Since the heated flow heating water must be passed from the boilers in the upper part of the hydraulic switch and since the cooled return heating water accumulates in the lower part of the hydraulic switch, the arrangement of the collector above and the distributor below this is particularly useful, since then in the shortest possible ways the required heating water flow is achieved.

In a specific embodiment of the last-described embodiment of the heating system is provided that the collector is at or near its soft end via a fixed connection line with the upper portion of the hydraulic switch in flow communication and that the distributor at its soft end via an opening in the him facing wall of the hydraulic switch with the lower region is in direct flow communication. Advantageously, no special line is required for the flow connection from the hydraulic switch to the distributor.

The fixed connection line from the collector to the upper section of the hydraulic separator may be a free-standing pipeline; but it is preferably designed as an integral part of the hydraulic switch, whereby a particularly compact design and a tidy appearance can be achieved.

In a concrete embodiment, the connecting line can be formed by a with the collector facing side of the switch tightly connected, preferably welded, rectangular tube or U-profile, the interior down through an opening with the collector and above another opening with the upper portion of hydraulic Switch is in fluid communication. The connecting line is realized with minimal material and installation costs.

In order to facilitate a facilitated and associated with the least possible effort adaptation to different predetermined spatial conditions, are appropriate between the pipe bends on the one hand and the forward and reverse of the boiler on the other hand for spacing compensation, especially for height compensation, straight pieces of pipe, preferably with cutting ring fittings at their ends, insertable.

If an exact pre-planning is possible, it is alternatively preferably provided that in each case the pipe bends are designed with these straight pipe sections connecting with the supply and return lines of the boiler as integral pipe elements.

In order to use one-piece pipe elements even if dimensional tolerances or changes still have to be considered and compensated for, it is provided that the pipe elements are flexible and / or length-variable.

A concrete embodiment of the tube elements with the desired flexibility and / or length variability consists e.g. in that they are designed as corrugated pipes.

Depending on the spatial conditions in a boiler room different boiler arrangements may be useful. A first embodiment of the cascade unit provides side by side side by side arranged boiler that the pipe elbows are all on the back or all on the front of collector and manifold attachable. The boiler headers and returns are then arranged substantially in a common vertical plane.

An alternative embodiment of the cascade unit provides for one or more pairs of back-to-back boilers that the pipe bends are mounted on both the back and on the front of the collector and distributor. The boiler headers and returns are then arranged in two horizontally spaced-apart vertical planes. This arrangement is particularly compact and can be accommodated independently of a wall surface freely within a room. The boilers are then e.g. held on the floor standing and / or fixed to the ceiling straps. Thus, this embodiment of the cascade unit according to the invention also provides solutions for particularly difficult spatial conditions in the boiler room.

To avoid energy losses by heat radiation and also to avoid noise emission is proposed according to the invention that the cascade unit and the pipe bends and straight pipe sections with a prefabricated, multi-part and shape-matched insulating against heat loss can be isolated. At the same time, the insulation shell counteracts possibly disturbing noise emission as a result of the water flow in the cascade unit.

To further simplify and speed up the assembly of the cascade unit, it is proposed that it be with floor mounted feet and / or with attachable to a wall or ceiling straps is equipped.

In order to be able to compensate, as easily as possible, particularly frequently occurring dimensional and positional deviations on site, the feet and / or support are expediently height-adjustable and / or length-adjustable.

Figur 1

eine erste Kaskadeneinheit in schematischer Ansicht auf ihre Vorderseite,

Figur 2

die Kaskadeneinheit aus Figur 1 in schematischer Ansicht auf ihre rechte Seite gemäß dem Pfeil II in Figur 1,

Figur 3

die Kaskadeneinheit aus Figur 1 in schematischer Ansicht auf ihre Rückseite und

Figur 4

die Kaskadeneinheit in einer zweiten Ausführung zusammen mit einem von mehreren Heizkesseln in schematischer Ansicht auf ihre linke Seite.

An embodiment of the invention will be explained below with reference to a drawing. The figures of the drawing show:

FIG. 1

a first cascade unit in a schematic view of its front side,

FIG. 2

the cascade unit off FIG. 1 in a schematic view on their right side according to the arrow II in FIG. 1 .

FIG. 3

the cascade unit off FIG. 1 in a schematic view on her back and

FIG. 4

the cascade unit in a second embodiment together with one of several boilers in a schematic view on their left side.

FIG. 1 The drawing shows a first example of a cascade unit 1 for a heating system with one to four boilers. The boilers, which are not shown here, for example, are mounted side by side and / or back to back over the cascade unit 1. Each boiler has for the heating medium, usually water, a flow and a return, which are each to be connected to the cascade unit 1.

The cascade unit 1 each comprises a boiler inlet header 3 and a boiler return manifold 4. These are combined as a unit and each executed in the form of a rectangular tube, wherein the two rectangular tubes lie directly on top of each other and extend in the horizontal direction. With the overhead collector 3 are on its here facing the viewer front and on the side facing away from the viewer back ever two connecting pieces 33, 33 'in the form of short straight, horizontally extending pipe sections tightly, suitably welded. In the same way, two connecting pieces 44, 44 'are connected at the front and at the rear of the distributor 4 located directly below the collector, which are also designed as short, straight, horizontally extending pieces of pipe. As a result, viewed in the horizontal direction, both front side and rear side, an alternating arrangement of flow and return connection piece 33 and 44 or 33 'and 44'.

With the interposition of one not shown here, initially loosely supplied pipe bend each required according to the number and arrangement of the boiler connecting piece 33 and / or 33 'with the headers and the connecting pieces 44 and / or 44' can be connected to the return of the boiler.

Furthermore, the cascade unit 1 comprises a hydraulic switch 5, which in the view according to FIG. 1 is arranged on the right side of the cascade unit 1. The hydraulic switch 5 has a vertically extending housing 50, which in its lower portion mechanically fixed to the assembly of collector 3 and manifold 4 is connected, preferably welded. From the right end region of the collector 3, an integrated connection line 35 leads into the upper region of the housing 50 of the hydraulic separator. The connecting line 35 is below via an opening 53 with the interior of the collector 3 and above an opening 53 'with the interior of the switch 5 in flow communication.

The distributor 4 opens through an opening 54 in the wall of the housing 50 of the hydraulic switch 5 directly in the lower region. At her in the FIG. 1 right side has the hydraulic switch 5 above a heating circuit feed connection 55 and below a heating circuit return connection 56, which serve for connection to one or more heating circuits with heat consumers.

Furthermore, in the unit 1 according to FIG. 1 in the interior of the housing 50 of the switch 5 in the upper part at a distance from the opening 53 'a baffle plate 57 is provided, which is designed as a perforated plate or grid and should cause a reduction in the flow velocity.

The collector 3 and the manifold 4 with their connecting piece 33, 33 ', 44, 44', the hydraulic switch 5 and the integrated pipe 35 are combined to form a prefabricated transportable construction and assembly unit, which allows a rational production. To set up the cascade unit 1, two feet 11 are mounted on the distributor 4 on the underside, which can be placed on the floor of a boiler room and record the weight of the unit 1.

On the far left of the collector 3, a drain pipe 32 can be seen, which serves to demand-like draining the heating water from the collector 3 and is normally closed. At the hydraulic switch 5 sits at the top of a nozzle 51, which receives, for example, a temperature sensor and / or a vent valve. At the bottom of the hydraulic separator 5, a further nozzle 52 is provided, which is also closed in normal operation and which serves as needed for sludge removal and emptying of the switch 5.

In the operation of a cascade heating system, one or more boilers are operated depending on the current heat demand, preferably the boilers are also designed with modulable burner systems, so that the performance of each boiler can be changed. Thus, a wide range of heating power requirements is very economical coverable, which ensures a cost-effective and environmentally friendly heating operation. At the same time, the installation of the heating system using the prefabricated cascade unit 1 is advantageously simple.

FIG. 2 the drawing shows the cascade unit 1 FIG. 1 in a side view from the right according to the arrow II in FIG. 1 , Visible here is essentially only the hydraulic switch 5 with the top arranged heating circuit feed connection 55 and the bottom arranged heating circuit return connection 56. At the hydraulic switch 5 sits at the top of the end face of the nozzle 51 and at the bottom of the hydraulic switch 5 is the other nozzle 52 visible.

The collector 3 and the manifold 4 are covered by the hydraulic switch 5 with the exception of their connected connecting pieces 33, 33 ', 44 and 44'. As FIG. 2 clearly shows, in the illustrated embodiment of the cascade unit 1, the hydraulic switch 5 is designed with a width or depth dimension, which corresponds to that of the collector 3 and the manifold 4. This also makes the production of the unit 1 is kept simple and inexpensive.

At the bottom of FIG. 2 one of the feet 11 is visible, with which the unit 1 can be supported on a boiler room floor.

FIG. 3 the drawing shows the cascade unit 1 FIG. 1 now in view on her in FIG. 1 rear facing back. As a result, lies in FIG. 3 now the hydraulic switch 5 left of the assembly of collector 3 and distributor 4. The in FIG. 1 lying on the front connecting piece 33, 44 are now on the in FIG. 3 rear facing side of header 3 and manifold 4; in the FIG. 1 to the rear facing connecting piece 33 ', 44' are accordingly now on the in FIG. 3 the viewer facing side of collector 3 and 4 distributor.

Like a comparative look at the FIGS. 1 and 3 shows lie in both orientations of the cascade unit 1, which in the FIGS. 1 and 3 are shown, pairs of connecting pieces 33, 44 and 33 ', 44' side by side so that at the side facing away from the viewer side always left the return port and right of the flow connection. Thus, in both orientations of the cascade unit 1, the heats and returns of a Boiler or an arrangement of several boilers easily and standard-compliant with the associated connection piece 33, 44 and 33 ', 44' are connected without unwanted pipe crossings are necessary. The cascade unit 1 can therefore be used both in an alignment with the hydraulic switch 5 arranged on the right and in an alignment with the hydraulic switch 5 arranged on the left, without requiring any changes to the cascade unit 1. Thus, if necessary, it can still be decided on site at the construction site, in which orientation the cascade unit 1 is expediently installed in the heating system.

Regarding the further in FIG. 3 visible details and reference numbers will be to the description of Figures 1 and 2 directed.

FIG. 4 shows a second embodiment of the cascade unit 1, now together with one of several boilers 2, which are connected to the cascade unit 1. It is in the FIG. 4 the viewing direction of the representation is selected such that it falls on the left end side of the cascade unit 1.

Down in FIG. 4 Here are the boiler flow collector 3 and immediately below the boiler return manifold 4 visible. The collector 3 and the manifold 4 are also here each formed by a rectangular tube, which extend horizontally and are mounted on each other. At the viewer facing the front end of the collector 3, the discharge nozzle 32 is visible.

In the background lies in FIG. 4 the hydraulic switch 5, which faces away from the viewer with the front ends of Collector 3 and distributor 4 is connected to the pre-assembled cascade unit 1. Structure and function of the hydraulic switch 5 according to FIG. 4 correspond to the hydraulic switch 5 according to the previously explained FIGS. 1 to 3 ,

At the front, in FIG. 4 So right, as well as on the back, in FIG. 4 left, of collector 3 and manifold 4 each connecting piece 33, 33 'and 44, 44' are mounted. These connecting pieces 33, 33 ', 44, 44' here also have the form of short, straight pipe socket with a connection end.

In the in FIG. 4 shown example are connected to the back of the collector 3 and manifold 4 facing connecting piece 33 ', 44' pipe bends 22, 22 '. These pipe bends 21, 21 'each form an upwardly pointing 90 ° bend. In continuation of the pipe bends 21, 21 'are here straight pipe sections 22, 22' are arranged, which are connected at their upper end to the boiler 2, more precisely, the flow and return connections. Immediately below the boiler 2, a shut-off valve is provided in each case, wherein due to the line of sight in FIG. 4 only the observer facing the shut-off valve 23 between the upper end of the straight pipe section 22 and the boiler 2 can be seen. This shut-off valve 23 allows a shut-off of the boiler flow. Another, here concealed shut-off valve allows a shut-off of the boiler return if required.

As the FIG. 4 further shows, in each case a pipe bend 21, 21 'and an associated straight pipe section 22, 22' are each a one-piece tubular element 20, 20 'summarized, each as a flexible and variable-length corrugated pipe is executed. Thus, the radius of the pipe bend 21, 21 'can be adjusted as needed. In addition, the length of the straight pipe section 22, 22 'in a sufficiently large extent variable in order to compensate for tolerances and positional deviations compulsory and with little effort.

The unoccupied connecting pieces 33, 44 at the front of the cascade unit 1, in FIG. 4 that is, the connecting pieces pointing to the right, each with a cap or a blanking plug 24, 24 'liquid-tightly closed.

At the bottom of FIG. 4 Finally, one of the feet 11 can still be seen, with which the cascade unit 1 stands on the floor of a boiler room.

Claims (16)

1. A cascade unit (1) for a heating system with two or more heating boilers (2), in particular with suspended condensing boilers, with a hydraulic shunt (5) which is connectable on the one hand with the inlet flows and return flows of all heating boilers (2) and on the other hand with at least one heating circuit inlet flow (55) and heating circuit return flow (56) each, with the cascade unit (1) furthermore comprising one each of the essentially horizontally extending boiler inlet flow header (3) and boiler return flow manifold (4), the header (3) and the manifold (4) being directly stacked and firmly connected with the hydraulic shunt (5) and forming with it the cascade unit (1) presenting a pre-fabricated, transportable modular and assembly unit, and the header (3) and the manifold (4) each being designed with prepared connecting nozzles (33, 44; 33', 44') fittingly placed for a group of two or more heating boilers (2) for the connection of the heating boiler inlet flows and the heating boiler return flows,
   characterized in that

   - the connecting nozzles (33, 44; 33', 44') are designed in the form of short, horizontally extending straight pipe sections;

   - either a pipe bend (21, 21') extending in direction towards the corresponding heating boiler (2) or a blind plug (24, 24') is mountable on each connecting nozzle (33, 44; 33', 44');

   - seen in the longitudinal direction of header (3) and manifold (4), the connecting nozzles (33, 44; 33', 44') are each alternately arranged on the front and on the rear of the header (3) and of the manifold (4);

   - one connecting nozzle (33, 33') each of the header (3) and one connecting nozzle (44', 44) each of the manifold (4) form a pair of two connecting nozzles (33, 44'; 33', 44) aligned opposite to each other and equidistant from the hydraulic shunt(5); and

   - after a rotation of the cascade unit (1) about a vertical axis by 180°, a position of the hydraulic shunt (5) results which is changed from left to right or from right to left relative to header (3) and manifold (4) which is, however, an arrangement of all connecting nozzles (33, 44; 33', 44') identical with the previous arrangement.
2. Cascade unit according to claim 1, characterized in that the connecting nozzles (33, 44; 33', 44') are designed with flat-packed connecting nipples (34, 45; 34', 45').
3. Cascade unit according to claim 1 or 2, characterized in that the header (3) and the manifold (4) are designed as stacked rectangular pipes, preferably with a joint center wall.
4. Cascade unit according to any one of the claims 1 to 3, characterized in that the header (3) lies on top and the manifold (4) on the bottom and that header (3) and manifold (4) are mechanically firmly connected at their one front end with the essentially vertically aligned hydraulic shunt (5) near its lower end.
5. Cascade unit according to claim 4, characterized in that the header (3) is, at or near its shunt-side end, in flow connection with the upper area of the hydraulic shunt (5) via a fixed connecting line (35) and that the manifold (4) is, at its shunt-side end, in direct flow connection with the lower area of the shunt (5) via an opening (54) in the wall of the hydraulic shunt (5) facing it.
6. Cascade unit according to claim 5, characterized in that the fixed connecting line (35) is designed as an integrated component part of the hydraulic shunt (5).
7. Cascade unit according to claim 6, characterized in that the connecting line (35) is formed by a preferably welded rectangular pipe or U-section which is tightly connected with the side of the shunt (5) facing the header (3) and whose interior is in flow connection - on the bottom via an opening (53) - with the header (3) and on the top via another opening (53') with the upper area of the hydraulic shunt (5).
8. Cascade unit according to any one of the claims 1 to 7, characterized in that - between the pipe bends (21, 21') on the one hand and the inlet and return flows of the heating boilers (2) on the other hand - straight pipe sections are insertable, preferably with cutting ring screw connections at their ends, to equalize the spacing.
9. Cascade unit according to any one of the claims 1 to 7, characterized in that the pipe bends (21, 21') are each designed as one-piece pipe elements (20, 20') with straight pipe sections (22, 22') connecting them with the inlet and return flows of the heating boilers (2).
10. Cascade unit according to claim 9, characterized in that the pipe elements (20, 20') are designed flexibly and/or variable in length.
11. Cascade unit according to claim 10, characterized in that the pipe elements (20, 20') are designed as corrugated pipes.
12. Cascade unit according to any one of the preceding claims, characterized in that, for heating boilers (2) arranged side by side, the pipe bends (21, 21') are mountable all on the rear side or all on the front side of header (3) and manifold (4).
13. Cascade unit according to any one of the claims 1 to 11, characterized in that, for one pair or a plurality of pairs of heating boilers (2) arranged back to back, the pipe bends (21, 21') are mountable on the rear side as well as on the front side of header (3) and manifold (4).
14. Cascade unit according to any one of the preceding claims, characterized in that the cascade unit (1) and the pipe bends (21, 21') and straight pipe sections (22, 22') can be insulated against thermal losses by means of a prefabricated, multipart and formfitting insulating shell.
15. Cascade unit according to any one of the preceding claims, characterized in that it is provided with feet (11) which can be placed on a floor and/or with brackets mountable on a wall or ceiling.
16. Cascade unit according to claim 15, characterized in that the feet (11) and/or the brackets are adjustable in height and/or length.

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