DEVICE FOR THE CONSTRUCTION OF A DISTRICT HEATING SUBSTATION AND THE SUBSTATION CONTAINING IT

Abstract

TITLE: DEVICE FOR CONSTRUCTING A DISTRICT HEATING SUBSTATION AND THE SUBSTATION COMPRISING IT. The device (400) for constructing a district heating substation comprises: - at least one horizontal base (405), - uprights (170), - a plurality of supports (175) for fixing uprights in a vertical position on a horizontal base, and - on at least one vertical upright, a collar (210) configured to retain a pipe (270) in position. Figure for the abbreviation: Figure 7

Description

Title of the invention: DEVICE FOR CONSTRUCTING A HEATING SUBSTATION URBAN AND SUBSTATION CONTAINING IT Technical field of the invention

[0001] The present invention relates to a device for constructing a district heating substation and a substation comprising it. State of the art

[0002] In order to limit greenhouse gas emissions, several urban areas have opted for district heating. The principle is an underground network that carries heated water under pressure throughout the city. Powered by a production unit, the network distributes heat to the buildings connected to it (hospitals, schools, high schools, colleges, apartment buildings, etc.). This heated water is transported through pipes serving the buildings, which are equipped with delivery points called substations.

[0003] Existing substations have many drawbacks. First, their high price, as they are custom-made to meet specific constraints such as size, power, schematic diagram, orientation, etc. Furthermore, there is a risk of damage during transport. This transport is also expensive. Handling substations is complex because their mass exceeds 150 kg. Delivery presents difficulties in moving them to and within the receiving room, as they must navigate corridors, staircases, narrow doorways, etc., and the receiving room may be small. Finally, the shortage of skilled pipefitters / welders and supplier delivery times, for example for meters and heat exchangers, result in very long installation times. Summary of the invention

[0004] The present invention aims to overcome all or part of these drawbacks with a substation concept based on several models, all sharing the same basic design. This design allows the substation to be adapted to the orientation of existing networks. An adaptable chassis allows for the acceptance of the different models. The substations

[0005] The modular design of the substations allows them to be sold and delivered as kits for direct assembly in the reception area or on a skid without the need for a pipefitter / welder. It should be noted that a skid is a mobile chassis-type structure on which a set of equipment, piping, and / or industrial materials is mounted. This allows for the transport of a range of functions "Ready to use" and pre-assembled, rather than transporting and assembling each unit individually on-site, this modular design also facilitates component replacement thanks to the interchangeability of the modules (for repairs, power upgrades, etc.). This design also allows for assembly without the heat exchanger and / or meter, reducing installation time. Each substation is designed to be compact once assembled, for example, with a footprint of 0.68 m² to 1.5 m² depending on the configuration. Maintenance is low-cost, simply requiring module replacement.

[0006] The invention also allows for retrofitting thanks to the interchangeability of the modules. For example, the collars are compatible with nominal diameters (“DN”) up to DN100, i.e. 100 mm.

[0007] In this design, vertical supports allow the substation to be adapted to the piping of different types of heat exchangers. The inventor has found that the assembly of such a substation is simple and quick: it is carried out by an installer or maintenance technician in less than three hours.

[0008] The design is intended to accommodate several heat exchanger capacities and accept different orientations. In addition, the very compact design allows the substation to be adapted to all premises.

[0009] The components supported by the kit, comprising the base, vertical supports, feet and clamps, include: - a heat exchanger, - a filter, - a pressure gauge on the primary circuit, and - a pressure gauge on the secondary circuit.

[0010] The configurations include valves on the main piping of the secondary network. Brief description of the figures

[0011] Other advantages, purposes and particular features of the invention will become apparent from the following non-limiting description of at least one particular embodiment of the device and substation that are the subject of the present invention, with reference to the accompanying drawings, in which:

[0012] [Fig-1] schematically represents the positioning of a substation subject to The invention, between a primary heat network and a secondary heat network,

[0013] [Fig.2] schematically represents a first embodiment of a fixing base for a vertical upright on a plinth,

[0014] [Fig.3] shows, in front view, two parts of a first embodiment of a collar mounted on a vertical post and supporting a pipe,

[0015] [Fig.4] schematically represents the positioning of an exchanger between a primary network and a secondary network,

[0016] [Fig. 5] schematically represents, in top view, a base equipped with bases and vertical uprights, in a first configuration of the device that is the subject of the invention,

[0017] [Fig.6] represents, in perspective, a first configuration of the device which is the object of the invention, naked,

[0018] [Fig.7] represents, in perspective, the device illustrated in [Fig.6], after assembly of a heat exchanger and piping,

[0019] [Fig.8] schematically represents, in top view, a base equipped with bases and vertical uprights, in a second configuration of the device that is the subject of the invention,

[0020] [Fig.9] represents, in perspective, a second configuration of the device that is the subject of the invention, naked,

[0021] [Fig. 10] represents, in perspective, the device illustrated in [Fig. 9], after assembly of a heat exchanger and piping,

[0022] [Fig. 11] schematically represents, in top view, a base equipped with feet and vertical uprights, in a third configuration of the device which is the subject of the invention,

[0023] [Fig. 12] represents, in perspective, the components of a third configuration of the device that is the subject of the invention,

[0024] [Fig. 13] represents, in perspective, the components illustrated in [Fig. 12], assembled in the third configuration of the device that is the subject of the invention,

[0025] [Fig. 14] represents, in perspective, the device illustrated in [Fig. 13], after assembly of a heat exchanger and piping,

[0026] [Fig. 15] represents, in perspective, a complete substation of the invention, comprising the device of the invention, in a third configuration,

[0027] [Fig. 16] shows, in front view, two parts of a second embodiment of a collar mounted on a vertical post and supporting a pipe,

[0028] [Fig. 17] represents, in perspective, the components of a variant of the third configuration of the device which is the subject of the invention, comprising collars illustrated in [Fig. 16] and vertical uprights of different dimensions,

[0029] [Fig. 18] represents, in perspective, a variant of the first configuration of the device which is the subject of the invention, comprising collars illustrated in [Fig. 16] and vertical uprights of different dimensions,

[0030] [Fig. 19] represents, in perspective, the device illustrated in [Fig. 18], on which pipes and a heat exchanger are mounted, and

[0031] [Fig.20] represents, in perspective, a second embodiment of a base fixing a vertical upright to a base. Description of the implementation methods

[0032] The present description is given by way of non-limiting grammar, each feature of an embodiment being able to be advantageously combined with any other feature of any other embodiment.

[0033] It should be noted from the outset that the figures are not to scale.

[0034] As can be understood from reading the present description, various concepts The inventive features can be implemented by one or more methods or devices described below, several examples of which are provided herein. The actions or steps performed in implementing the method or device can be ordered in any appropriate manner. Consequently, it is possible to construct embodiments in which the actions or steps are performed in a different order than that illustrated, which may include performing certain acts simultaneously, even if they are presented as sequential acts in the illustrated embodiments.

[0035] The expression "and / or", as used in this document and in the claims, shall be understood as meaning "either or both" of the elements thus joined, that is, elements that are present conjunctively in some cases and disjunctively in others. The multiple elements listed with "and / or" shall be interpreted in the same way, that is, "one or more" of the elements thus joined. Other elements may be present, other than the elements specifically identified by the "and / or" clause, whether or not they are related to those specifically identified elements.Thus, by way of non-limiting example, a reference to "A and / or B", when used in conjunction with an open language such as "including", may refer, in one embodiment, to A only (possibly including elements other than B); in another embodiment, to B only (possibly including elements other than A); in yet another embodiment, to A and B (possibly including other elements); etc.

[0036] As used herein in the description and in the claims, "or" should be understood inclusively.

[0037] As used in this description and in the claims, the expression "at least one", with reference to a list of one or more items, should be understood as meaning at least one item chosen from one or more items in the list of items, but not necessarily including at least one of each item specifically listed in the list of items and not excluding any combination of elements in the list of elements. This definition also allows the optional presence of elements other than the specifically identified elements in the list of elements to which the expression "at least one" refers, whether or not they are related to these specifically identified elements.Thus, by way of non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B", or, equivalently, "at least one of A and / or B") may refer, in one embodiment, to at least one, possibly including more than one, A, without B present (and possibly including elements other than B); in another embodiment, to at least one, possibly including more than one, B, without A present (and possibly including elements other than A); in yet another embodiment, to at least one, possibly including more than one, A, and at least one, possibly including more than one, B (and possibly including other elements); etc.

[0038] In the claims, as well as in the description below, all transitive expressions such as "comprising", "including", "carrying", "having", "containing", "implying", "holding", "composed of", and others, shall be understood as open, that is to say, as meaning including but not limited to. Only the transitive expressions "consisting of" and "consisting essentially of" shall be understood as closed or semi-closed transitive expressions, respectively.

[0039] Figure 1 schematically shows the positioning of a substation 100, the object of the invention, between a primary heating network 105 and a secondary heating network 110. The primary heating network 105 is heated by a boiler room 115 comprising boilers 120 and a fuel source 125, for example, a gas distribution network. The secondary network 110 is shown here in an apartment building 130. The boiler room 115 heats the water circulating in the primary network 105, which carries it to the heat exchange substation 100. The water in the secondary network 110 is heated there by heat exchange with the water in the primary network 105 and circulates between the apartments in the building 130 to heat them.

[0040] As illustrated in Figures 5, 8, and 11, a device of the invention takes the form of a modular frame 400, 500, and 600 comprising at least one base 405, 505, 605, and 606 provided with through holes 160, preferably tapped. This base 405, 505, 605, and 606 is, for example, formed from a rectangular galvanized steel plate folded on its four edges after its four corners have been removed. As shown opposite three examples of configurations of the device of the invention, the position of the tapped holes 160 on the base 405, 505, and 605 can vary depending on the configuration. However, preferably, the bases 405, 505, and 605 are identical and their tapped holes 160 are in the same positions. In [Fig. 11], the base 605 is complemented by a base 606.

[0041] The device 400, 500, and 600 also includes feet 175 or 176 for attaching vertical uprights 170 perpendicular to the plane of the base 405, 505, 605, or 606. In the example shown in [Fig. 2], the vertical uprights are square-section profiles made of galvanized steel. In this example, the mounting feet 175 take the form of profiles with a vertical body 190, a horizontal L-shaped cross-section, and two equal sides. The lower ends 180 are bent at right angles to form horizontal tabs once the vertical upright 170 is positioned on the horizontal base 405, 505, 605, or 606 for mounting. The bases 175 are, for example, made by folding a rectangular plate of galvanized steel, then drilling, for example with a punch, oblong openings 185 on the legs 180 and oblong openings 195 on the body 190.Tapped holes 200 on the vertical uprights 170 allow screws to be screwed through the oblong openings 195. The mounting of the feet 175 of the vertical uprights 170 onto the base 400, 500, 605 or 606 is done in the same way, by screwing screws through the oblong openings 185 of the legs 180, in the tapped holes 160.

[0042] In the example shown in [Fig. 20], the mounting brackets 176 have a vertical L-shaped cross-section with equal sides. The lower end 181 is bent at a right angle to the upper part 191 to form horizontal tabs once the vertical upright 170 is positioned on the horizontal base 405, 505, 605, or 606 for mounting. The brackets 176 are, for example, made by folding a galvanized steel plate and then punching, for example, oblong openings 186 in the horizontal part 181 and oblong openings 196 in the vertical part 191. Again, the tapped holes 200 in the vertical uprights 170 allow screws to be driven through the oblong openings 196.The mounting of the feet 176 of the vertical uprights 170 on the base 400, 500, 605 or 606 is done in the same way, by screwing screws through the oblong openings 186 of the horizontal parts 181 into the tapped holes 160.

[0043] In [Fig. 3], two parts 215 and 220 of a collar 210 are shown. Each of these parts 215 and 220 is flat and U-shaped. The lower part 215 has a groove 240 with two oblique flanks, inclined, once the collar 210 is mounted, at 45 degrees to the vertical. The lower part 215 also has a vertical oblong opening 225 and threaded openings 235. The upper part 220, on the other hand, has a semicircular groove 245. The upper part 220 also has two oblong openings 230, on either side of the groove 245. The spacing between the oblong openings 230 is equal to that between the threaded openings 235. Thus, once a pipe is positioned on the groove 240, the groove 245 of the upper part 220 can be placed against this pipe and screws 255 passing through the oblong openings 230 can be fixed on the threaded openings 235 to lock the two parts of the collar 210 in their respective positions. The parts 215 and 220 are, for example, made of galvanized steel.

[0044] The oblong opening 225 is used to adjust the height of the pipe relative to the base 405, 505, 605, or 606, by receiving several screws 260 which are tightened into threaded openings 250 in the vertical upright 170, as illustrated in [Fig. 3]. In [Fig. 3], a pipe 270 is thus positioned and held by a clamp 210 mounted on a vertical upright 170. For example, the holes 200 and 250 are steel inserts, while the holes 160 and 235 are threaded.

[0045] In [Fig.4], various components of a substation 300 comprising a heat exchanger 350 are observed. A pressure gauge 305 is positioned on the hot water inlet from the primary network 105. A pressure gauge 310 is positioned on the hot water outlet leading to the secondary network 110. Similarly, temperature sensors 315 to 330 are respectively placed on the pipes.

[0046] We also observe, in [Fig.4], a meter 355, a union or flange fitting 360 from the nominal diameter of 65 mm, a steel sleeve 365 for probe, a filter 370, a two-way valve 375, two screw T fittings 380 and 385, a threaded end 390 for safety valve and a union or flange fitting 395 from the nominal diameter of 50 mm, for filter.

[0047] All the elements illustrated in [Fig.4] are supported by the vertical uprights 170, except for the heat exchanger 350, which is supported by its manufacturer's chassis, itself supported, for small power ratings, by the vertical uprights 170.

[0048] In the first configuration of a device 400, illustrated in figures 5 to 7, we find: a base 405 with threaded openings 160, vertical uprights 170, feet 175 for fixing vertical uprights 170 and collars 210 for supporting pipes 270. A heat exchanger 480 is connected to pipes 270.

[0049] In the second configuration of a device 500, illustrated in figures 8 to 10, we find the elements constituting the device 400, the numerical references being incremented by 100: a base 505 provided with threaded openings 160, vertical uprights 170, feet 175 for fixing vertical uprights 170 and collars 210 for supporting pipes 270. A heat exchanger 580 is connected to pipes 270.

[0050] In the third configuration of a device 600, illustrated in Figures 11 to 15, we find the elements constituting the device 400, with the numerical references incremented by 200: a base 605 provided with threaded openings 160, some vertical uprights 170, feet 175 for fixing vertical uprights and collars 210 for supporting pipes 270. A heat exchanger 680 is connected to pipes 270. In this third configuration, an additional base 606 also carries at least one foot 175 for fixing vertical upright 170, to support at least one pipe 270.

[0051] Figure 15 shows a complete substation 700, the subject of the invention, comprising the device of the invention in its third configuration. In Figure 15, the primary network pipes are on the left and the secondary network pipes are on the right. In addition to the elements illustrated in Figure 14, this substation 700 comprises: - a 701 filter module on the primary network, - a 702 valve on the secondary network, - 703 thermometers, on each of the inlets and outlets of the primary and secondary networks, - 704 probes, on each of the inputs and outputs of the primary and secondary networks, - a pressure gauge 705 on the outlet of the heat exchanger 680 to the secondary network, - a pressure gauge 706 on the inlet of the heat exchanger 680 from the primary network, - 707 valves, notably at each end of the pipes in each of the primary and secondary networks, - a two-way valve (“V2V”) 708 on the inlet of the heat exchanger 680 from the primary network, and - a meter module 709 on the output of the heat exchanger 680 to the primary network.

[0052] A second embodiment of a collar 211 is shown in [Fig. 16], the upper part 220 of which is that of the first embodiment of the collar 210 illustrated in [Fig. 3]. However, the lower part 216 differs from the lower part 215 of the collar 210 in that the groove 240 is replaced by a series of circular arcs 241 to 244 and 246 of decreasing diameters, corresponding to the standard diameters of pipes used in district heating substations. For example, the diameters of the arcs are 76.4 mm, 60.3 mm, 48.3 mm, 42.4 mm and 33.7 mm.

[0053] Thus, standard diameter pipes are better supported by the 211 collar than by the 210 collar.

[0054] Figure 17 shows, in perspective, the components of a variant 610 of the third configuration of the device of the invention, comprising collars 211, and vertical uprights 620 of greater height than the vertical uprights 170, to support, in addition to pipes, an electrical panel for the district heating substation.

[0055] Fig. 18 represents, in perspective, the components of a variant 410 of the third configuration of the device of the invention, comprising collars 211, vertical posts 420 of greater height than the vertical posts 170 and horizontal posts 425 connecting the vertical posts 420 to support, in addition to pipes, an electrical panel of the district heating substation.

[0056] The two taller vertical posts 420 are connected to each other by steel plates 425. These two vertical posts 420 are 750mm taller than the vertical posts 170 to accommodate an electrical panel.

[0057] Fig. 19 represents the device 410 illustrated in Fig. 18, on which pipes 270 and a heat exchanger 480 are mounted.

[0058] It can be seen from the figures that the device of the invention is configured to support the heat exchanger in a cantilevered position, that is, outside the convex volume delimited by the vertical supports. The two-part collar is configured to accommodate and clamp pipes of different diameters.

[0059] It should also be noted that the bases 405, 505 and 605 are identical, both in terms of construction and in terms of the positioning of the threaded openings. Thus, during installation, the same base is compatible with each of the three configurations of the device and the substation that are the subject of the invention.

[0060] As can be understood from the preceding description, the present invention aims to remedy all or part of the drawbacks of the prior art with a substation concept based on several models, all sharing the same basic design. This design allows the substation to be adapted to the orientation of existing networks. An adaptable chassis allows for the acceptance of the different models.

[0061] The modular design of the substations allows them to be sold and delivered as kits for direct installation in the building or on a skid without the need for a pipefitter / welder. This modular design also facilitates component replacement thanks to the interchangeability of the modules (repair, power upgrade, etc.). This design also allows assembly without the heat exchanger and / or meter, which reduces installation time. Each substation is designed to be compact once assembled, for example, with a footprint of 0.68 m² to 1.5 m² depending on the configuration. Maintenance is low-cost, simply by replacing the modules.

[0062] The invention also allows for retrofitting thanks to the interchangeability of the modules. For example, the collars are compatible with nominal diameters (“DN”) up to DN100, i.e. 100 mm.

[0063] In this design, vertical uprights allow the substation to be adapted to the piping of the different types of exchangers.

[0064] Further information on the technical characteristics, purposes and advantages of the device and substation which are the subject of the invention is given below.

[0065] Due to its design, the device that is the subject of the invention can have a reduced selling price, for example, divided by three for several of the configurations presented above. Its assembly is quick and easy: it is delivered as a kit and the substation can be assembled by a fitter or maintenance technician in less than three hours, thanks to the included instructions.

[0066] The modular design allows: - Low-cost maintenance, simply by changing the modules, and - Retrofitting thanks to the interchangeability of modules.

[0067] The design is intended to accommodate several heat exchanger capacities and accept different orientations. In addition, the very compact design allows the substation to be adapted to any premises.

[0068] The components supported by the kit comprising the base, vertical supports, feet and clamps include: - a heat exchanger, - a filter, - a pressure gauge on the primary circuit, and - a pressure gauge on the secondary circuit.

[0069] Examples of heat exchanger power according to the configurations described above are given below: Configuration 1: PN = 16, exchanger power = 0 - 200 KW. Configuration 2: PN = 16, exchanger power = 200 - 500 KW. Configuration 3: PN = 16, Exchanger power = 500 - 1000 KW.

[0070] These mobile substations can have several sets: - Piping, - Solenoid valve, - Counter, - Heat exchanger, - Electrical box and / or panel, and - Chassis constituting the device that is the subject of the invention.

[0071] This chassis is capable of accommodating various heat exchanger capacities and design configurations. The modular chassis allows for simple assembly in just a few minutes. This optimizes transport costs and enables direct installation of substations in confined spaces.

[0072] The frame is height-adjustable: thanks to the vertical supports and clamps, the pipe positioning can be adjusted. The clamps are configured to accept different pipe diameters. For example, they can accommodate pipes up to DN100.

[0073] Object and invention

[0074] The present invention aims to remedy all or part of these drawbacks.

[0075] To this end, according to a first aspect, the present invention relates to a device for constructing a district heating substation, which comprises: - at least one horizontal base, - uprights, - a plurality of upright fixing brackets in a vertical position on a horizontal base, and - on at least one vertical post, a collar configured to hold a pipe in position.

[0076] In embodiments, at least one collar has two flat, U-shaped parts, a lower part having a groove having two oblique sides, inclined once the collar is mounted, at 45 degrees to the vertical, an upper part having a semi-circular groove.

[0077] In embodiments, at least one collar comprises two flat, U-shaped parts, a lower part having a groove formed of arcs of circles of different diameters, and an upper part having a semi-circular groove.

[0078] In embodiments, at least one base has through holes corresponding to at least two district heating substation configurations.

[0079] In some embodiments, the through holes are tapped.

[0080] In embodiments, the device that is the subject of the invention comprises at least two horizontal, disjointed bases.

[0081] In embodiments, the device of the invention comprises uprights of greater height than the other uprights and configured to support an electrical panel.

[0082] According to a second aspect, the present invention relates to a district heating substation for thermally connecting a primary network and a secondary network, which comprises: - a device that is the subject of the present invention, - pipes supported and held in position by clamps of the device, and - a heat exchanger supported by the device.

[0083] In some embodiments, the heat exchanger is cantilevered by the pipes supported by the clamps of the device.

[0084] In some embodiments, the substation further comprises: - a filter module on the primary network, - a valve on the secondary network, - thermometers, on each of the inlets and outlets of the primary and secondary networks, - probes, on each of the inputs and outputs of the primary and secondary networks, - a pressure gauge on the outlet of the heat exchanger to the secondary network, - a pressure gauge on the inlet of the heat exchanger from the primary network, - valves at each end of the pipes in each of the primary and secondary networks, - a two-way valve on the heat exchanger inlet from the primary network, and - a meter module on the output of the heat exchanger to the primary network.

Claims

Demands

1. Device (400, 410, 500, 600, 610) for constructing a district heating substation, which includes: - at least one horizontal base (405, 505, 605, 606), - uprights (170, 420, 620), - a plurality of feet (175) for fixing uprights in a vertical position on a horizontal base, and - on at least one vertical upright, a collar (210, 211) configured to retain in position a pipe (270); characterized in that said at least one said collar (210) has a lower part (215) having a groove (240) having two oblique sides, inclined, once the collar is mounted, with respect to the vertical, or a groove (240) formed of arcs of circles (241, 242, 243, 244, 246) of different diameters.

2. Device (400, 500, 600) according to claim 1, wherein said at least one collar (210) comprises two flat, U-shaped parts (215, 220), a lower part (215) having a groove (240) having two oblique sides, inclined once the collar is mounted, at 45 degrees to the vertical, an upper part (220) having a semi-circular groove (245).

3. Device (410, 610) according to any one of claims 1 or 2, wherein said at least one collar (211) comprises two flat, U-shaped parts (216, 220), a lower part (216) having a groove (240) formed of arcs of circles (241, 242, 243, 244, 246) of different diameters, an upper part (220) having a semi-circular groove (245).

4. Device (400, 410, 500, 600, 610) according to any one of claims 1 to 3, wherein said at least one base (405, 505, 605) has through holes (160) corresponding to at least two district heating substation configurations.

5. Device (400, 410, 500, 600, 610) according to claim 4, wherein the through holes (160) are tapped.

6. Device (600, 610) according to any one of claims 1 to 5, which comprises at least two disjoint horizontal bases (605, 606).

7. Device (410, 610) according to any one of claims 1 to 6, which includes uprights (420, 620) of a height greater than the other uprights (170) and configured to support an electrical panel.

8. District heating substation (700) for thermally connecting a primary network and a secondary network, comprising: - a device (600) according to any one of claims 1 to 7, - pipes (270) supported and held in position by clamps (210, 211) of the device, and - a heat exchanger (680) supported by the device.

9. Substation (700) according to claim 8, wherein the heat exchanger (680) is cantilevered by the pipes supported by the clamps (210, 211) of the device (600).

10. Substation (700) according to any one of claims 8 or 9, further comprising: - a filter module (701) on the primary network, - a valve (702) on the secondary network, - thermometers (703) on each of the inlets and outlets of the primary and secondary networks, - probes (704) on each of the inlets and outlets of the primary and secondary networks, - a pressure gauge (705) on the outlet of the heat exchanger (680) to the secondary network, - a pressure gauge (706) on the inlet of the heat exchanger from the primary network, - valves (707) at each end of the pipes of each of the primary and secondary networks, - a two-way valve (708) on the inlet of the heat exchanger from the primary network, and - a meter module (709) on the outlet of the heat exchanger to the primary network.

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