Hybrid thermal plant for water heating

Abstract

A hybrid thermal plant (100) comprises: a frame (9), a combustion cell (1), a heat exchanger (2), a technical water circuit (5), a compressor (3), and a gas / water exchanger (4); the combustion cell and the heat exchanger are in fluid communication with each other; the frame (9) of the plant comprises at least one opening (92) for the entry of external air and the exit of an air-fumes3 flow from the plant (100); the plant (100) comprises an air distributor (7) and a single fan (6) arranged in the frame (9) upstream of the said air distributor (7); the air distributor (7) is in fluid communication with a first inlet (12c) of the combustion cell and with a first inlet (23) of the heat exchanger.

Description

[0001] The present patent application for an industrial invention relates to a hybrid thermal plant for water heating. In particular, the field of reference is that of hybrid plants, comprising a combustion cell and a heat pump.

[0002] Hybrid thermal plant are known, comprising: a frame; a gas boiler arranged in the frame and comprising a water / fumes exchanger intended to be connected to a water circuit to heat circulating water in said circuit; the boiler is designed to generate fumes from the combustion of gas and external air; a heat pump arranged in the frame; a first evaporator arranged in the frame and in fluid communication with the boiler, so that the fumes pass from the boiler to the first evaporator; the first evaporator comprises a refrigerant gas / fumes exchanger connected to a refrigerant gas circuit of the heat pump, in order to heat the refrigerant gas through the fumes generated by combustion; a second evaporator arranged in the frame and intended to be in fluid communication with the outside, so that external air enters the second evaporator; the second evaporator comprises a refrigerant gas / air exchanger connected to a refrigerant gas circuit of the heat pump, in order to heat the refrigerant gas using external air; a first fan to allow the intake of external air into the boiler; a second fan to allow the intake of external air into the second evaporator.

[0003] The frame comprises: an inlet intended to be in fluid communication with the outside for the entry of external air into the frame; a first outlet intended to be in fluid communication with the outside and in fluid communication with the first evaporator for the exit of the fumes from the plant; a second outlet intended to be in fluid communication with the outside and in fluid communication with the second evaporator for the exit of external air from the plant.

[0004] These known plants have a first drawback due to their difficult and complex installation, requiring the realization of three mouths in communication with the outside. Therefore, significant building and / or masonry works are necessary to allow the installation of the known hybrid plant. Additionally, the known hybrid plants are large in size, due to the fact that the known hybrid plants comprise two evaporators and two fans.

[0005] The known plants have a second drawback due to the fact that the heating of the refrigerant gas flowing in the second evaporator is strongly influenced by external environmental conditions, since the refrigerant gas is heated by the external air. Given the strong dependence on environmental conditions, large airflows of external air are needed, and consequently large evaporator heat exchange surfaces are required to heat the refrigerant gas using external air. Therefore, the second evaporator is usually bulky and contributes significantly to the overall size of the known hybrid thermal plant.

[0006] ITBO20120458 discloses a thermal plant comprising a combustion cell, a heat exchanger comprising an evaporator, a compressor, and a gas / water heat exchanger. The combustion cell comprises an inlet with a first fan for the intake of external air into the combustion cell. The heat exchanger comprises an inlet for the intake of external air into the heat exchanger. A second fan is arranged at an outlet of the heat exchanger for exit air and fumes from the heat exchanger. The flow of external air entering the combustion cell is regulated by modifying the rotational speed of the first fan. The flow of external air entering the heat exchanger is regulated by modifying the rotational speed of the second fan. The plant of ITBO20120458 has the drawback that the regulation of the flow of external air entering the combustion cell and the heat exchanger is regulated separately, by acting on the two fans separately. The use of two fans leads to high energy consumption and large volumes. Furthermore, the external air is not distributed between the combustion chamber and the heat exchanger according to the needs of both. In fact, it is known that the flow of external air entering the combustion cell must be low and simultaneously stable to ensure the maintenance of a stable flame in a burner of the combustion cell. The flow of external air entering the heat exchanger is preferably higher than the flow of external air entering the combustion cell, since the evaporator requires a high flow of external air to heat the refrigerant gas.

[0007] EP4056920 discloses a thermal plant comprising a boiler, a heat pump plant, a technical water plant, an evaporator, a first fan at an inlet of the boiler, and a second fan downstream of the evaporator.

[0008] FR2547027 discloses a thermal plant comprising a boiler, an evaporator, a fume evacuation duct from the boiler comprising an outlet near the evaporator, a first fan at an outlet of a frame of the plant, and a second fan in the duct.

[0009] EP3361179 discloses a monoblock heating device obtained by integrating a gas boiler and an air-to-water heat pump.

[0010] The purpose of the present invention is to overcome the drawbacks of the known art, providing a hybrid thermal plant that allows the distribution of external air between the combustion cell and the heat exchanger, based on the needs of both the combustion cell and the heat exchanger, and the regulation the airflow entering the combustion cell and the heat exchanger, while being simultaneously compact, lightweight, cost-effective, and easy to install.

[0011] Another purpose is to provide a hybrid thermal plant that allows efficient heating of the refrigerant gas of the heat pump, independently of the external air temperature.

[0012] These purposes are achieved in accordance with the invention having the features listed in the appended independent claim 1.

[0013] Advantageous embodiments appear from the dependent claims.

[0014] The hybrid thermal plant according to the invention is defined by claim 1.

[0015] The advantages of the plant according to the invention are evident, in fact, thanks to the fact that the plant comprises a single fan and an air distributor, it is possible to distribute the external air entering to both the combustion cell and the heat exchanger, thereby reducing the plant's energy consumption and size. In other words, instead of the two fans used in known plants, the plant according to the invention comprises one fan and an air distributor. In this way, the plant according to the invention has lower energy consumption, a smaller size, and reduced noise levels.

[0016] For greater clarity, the description of the plant according to the invention continues with reference to the attached drawings, which have a non-limiting illustrative purpose, wherein: Fig. 1 is a schematic lateral view of the plant according to the invention; Fig. 2 is an axonometric view of an upper portion of a frame of the plant according to the invention; Fig. 3 is a schematic lateral view of a variant of the plant according to the invention; Fig. 4 is a lateral view of an air distributor of the plant according to the invention; Fig. 5 is a section of the air distributor of Fig. 4; Fig. 6 is a section of a first variant of the air distributor of the plant according to the invention; Fig. 7 is a lateral view of a second variant of the air distributor of the plant according to the invention; Fig. 8 is a section of a third variant of the air distributor of the plant according to the invention.

[0017] With reference to Fig. 1, a hybrid thermal plant according to the invention is disclosed, generally indicated by reference number 100.

[0018] The plant (100) comprises: a frame (9); a combustion cell (1) arranged within the frame (9); a heat exchanger (2), arranged within the frame (9); a technical water circuit (5) arranged within the frame (9) and comprising a first section (50) designed to be connected via a first connector (53) to a return section of a technical water plant, and a second section (51) designed to be connected via a second connector (54) to a supply section of the technical water plant; a compressor (3), arranged within the frame (9) and connected to the heat exchanger (2); a gas / water exchanger (4), arranged within the frame (9) and connected to the compressor (3), the heat exchanger (2), and the technical water circuit (5).

[0019] The combustion cell (1) comprises a frame (10) that defines a chamber (11).

[0020] The combustion cell (1) comprises a burner (12), optionally arranged in the chamber (11) of the combustion cell and designed to ignite a combustion of gas and external air, generating high-temperature fumes.

[0021] The combustion cell (1) comprises: a first inlet (12c) for the entry of external air to supply to the burner (12); optionally, the first inlet (12c) leads into the chamber (11) of the combustion cell; a second inlet (12d) connected to a gas channel (12e) intended to be connected via a third connector (12f) to a gas plant for the entry of gas to supply to the burner (12); advantageously, the second inlet (12d) of the combustion cell is near the first inlet (12c) of the combustion cell and leads into the chamber (11) of the combustion cell.

[0022] The chamber (11) of the combustion cell is designed to contain the fumes generated by the burner (12).

[0023] Optionally, the combustion cell (1) comprises a mixing device arranged upstream of the burner (12) and designed to pre-mix external air and gas before said external air and gas enter the burner (12). Alternatively, if the mixing device is absent, the external air and gas enter directly the burner (12).

[0024] The combustion cell (1) comprises a condensing water / fumes exchanger (15) arranged in the chamber (11) of the combustion cell so that the water / fumes exchanger (15) is externally surrounded by the fumes generated by the burner (12). The water / fumes exchanger (15) is connected to the technical water circuit (5), so that the water / fumes exchanger (15) is traversed by water from the technical water circuit (5). More precisely, the water / fumes exchanger (15) comprises an inlet (15a) connected to the first section (50) of the technical water circuit and an outlet (15b) connected to the second section (51) of the technical water circuit.

[0025] The water circulating in the water / fumes exchanger (15) is heated by the high-temperature fumes surrounding the water / fumes exchanger. It should be noted that the water / fumes exchanger (15) can be any type of heat exchanger, for example, coil, plate, or tube bundle.

[0026] Optionally, the water / fumes exchanger (15) is arranged in the chamber (11) of the combustion cell near the burner (12).

[0027] The heat exchanger (2) comprises a frame (20) that defines a chamber (21).

[0028] The heat exchanger (2) comprises an evaporator (22) arranged in the chamber (21) of the heat exchanger. The evaporator (22) is connected to the compressor (3) and the gas / water exchanger (4) and is designed to be passed through by refrigerant gas. The evaporator (22) comprises an inlet (22a) for the entry of refrigerant gas into the evaporator (22) and an outlet (22b) for the exit of refrigerant gas from the evaporator (22).

[0029] The heat exchanger (2) comprises a first inlet (23) formed in the frame (20) of the heat exchanger for the entry of external air into the chamber (21) of the heat exchanger.

[0030] The chamber (11) of the combustion cell and the chamber (21) of the heat exchanger are in fluid communication with each other, so that the fumes generated by the burner (12) surround both the water / fumes exchanger (15) of the combustion cell and the evaporator (22) of the heat exchanger.

[0031] The heat exchanger (2) comprises an outlet (24) for the discharge of an air-fumes flow from the chamber (21) of the heat exchanger.

[0032] The fumes produced in the combustion cell surround the water-fumes exchanger (15) in the chamber (11) of the combustion cell, heating the water circulating through the water-fumes exchanger (15), then pass into the chamber (21) of the heat exchanger, mix with external air, generating an air-fumes flow that surrounds the evaporator (22), heating the refrigerant gas circulating in the evaporator (22), and exits the chamber (21) of the heat exchanger through the outlet (24).

[0033] Advantageously, the combustion cell (1) comprises an outlet (16) for the discharge of the fumes from the chamber (11) of the combustion cell, and the heat exchanger (2) comprises a second inlet (26) for the entry of the fumes into the chamber (21) of the heat exchanger. The plant (100) comprises a first connection channel (90) connected to the outlet (16) of the combustion cell and the second inlet (26) of the heat exchanger for the passage of fumes from the chamber (11) of the combustion cell to the chamber (21) of the heat exchanger.

[0034] Optionally, the outlet (24) of the heat exchanger is formed at the bottom of a side wall of the frame (20) of the heat exchanger. In this way, an ascending flow of fumes is created in the chamber (11) of the combustion cell and a descending flow of fumes and air is created in the chamber (21) of the heat exchanger.

[0035] Also with reference to Fig. 2, the frame (9) of the plant comprises an opening (92) advantageously formed in a top wall of the frame (9) of the plant and designed to separately allows both the entry of external air into the frame (9) and the exit of the air-fumes flow from the plant (100). The plant (100) comprises a single outlet channel (91) connected to the outlet (24) of the heat exchanger and passing through the opening (92) of the frame of the plant, for the discharge of the air-fumes flow from the plant (100). Advantageously, the outlet channel (91) has a smaller size than the opening (92) of the frame of the plant, so that there is a gap between the edges of the opening (92) and the outlet channel (91) for the entry of air into the frame (9) of the plant from the outside. In this case, the opening (92) is unique.

[0036] Optionally, a splitter element (95) is arranged outside the frame (9) of the plant, on the opening (92) of the frame, and comprises the exit channel (91) and an inlet channel (93) for the entry of external air through the gap between the opening (92) of the frame of the plant and the exit channel (91).

[0037] Thanks to the fact that the fumes circulate only inside the combustion cell (1), the heat exchanger (2), the exit channel (91), and the first connection channel (90), the plant (100) comprises: a first airtight sealing level comprising the combustion cell (1), the heat exchanger (2), the exit channel (91), and the first connection channel (90) for the circulation of fumes; a second airtight sealing level comprising the frame (9) of the plant, designed to prevent the exit of air outside the plant (100).

[0038] In other words, the fumes produced by the combustion in the combustion cell (1) are not free to circulate within the frame (9) of the plant and are forced to flow within the first sealing level of the plant (100) until they exit the plant (100).

[0039] Thanks to the fact that the heat exchanger communicates with the combustion cell, the fumes generated by the combustion in the combustion cell pass from the combustion cell to the heat exchanger, heating the evaporator. In this way, thanks also to the first inlet of the heat exchanger, it is possible to heat the refrigerant gas circulating in the evaporator of the heat exchanger with a flow that comprises both external air and the high-temperature fumes generated by combustion in the combustion cell. This allows the use of a single evaporator that heats the refrigerant gas, reducing the size of the plant according to the invention, and a single exit for both the exhausted air and the fumes. Additionally, the fumes produced by combustion have a temperature higher than the external air and not dependent on environmental conditions. Therefore, the air-fumes flow has a higher, more stable, and less variable temperature compared to the temperature of external air alone. This increases the efficiency of the evaporator. The increased efficiency of the evaporator means that smaller exchange surfaces can be used compared to known evaporators. Therefore, it is possible to make more compact evaporators with smaller sizes with respect to the known evaporator.

[0040] The plant (100) comprises: an air distributor (7) arranged within the frame (9); a single fan (6) arranged in the frame (9) upstream of said air distributor (7), so that said fan (6) sucks in external air and conveys the air into the air distributor (7); advantageously, the fan (6) has a horizontal axis.

[0041] The air distributor (7) is in fluid communication with the fan (6), the first inlet (12c) of the combustion chamber and the first inlet (23) of the heat exchanger, so that the air distributor receives incoming external air from the fan (6) and distributes said external air both to the combustion cell (1) and to the heat exchanger (2).

[0042] The air distributor (7) is separated from the first communication channel (90) of the plant.

[0043] The air distributor (7) comprises: an inlet (70) connected to the fan (6) for the entry of external air into the air distributor (7); advantageously, said inlet (70) of the air distributor is connected to an outlet of the fan (6) by a sealing gasket; a first duct (71a) (Figs. 5, 6, and 8) ending with a first outlet (71) connected to the first inlet (12c) of the combustion cell; a second duct (72a) (Figs. 5, 6, and 8) ending with a second outlet (72) connected to the first inlet (23) of the heat exchanger.

[0044] Optionally, the second outlet (72) of the air distributor (7) is connected to the first inlet (23) of the heat exchanger through a second connecting channel (94) of the plant, to allow external air to flow from the air distributor (7) to the heat exchanger (2).

[0045] The first duct (71a) of the air distributor has a smaller section compared to a section of the second duct (72a) of the air distributor.

[0046] The advantages of the plant according to the invention are evident, wherein, thanks to the fact that that plant comprises a single fan and the air distributor, it is possible to distribute incoming external air to both the combustion cell and the heat exchanger, reducing energy consumption and the size of the plant. In other words, instead of two fans provided in known plant, the plant according to the invention comprises a single fan and an air distributor. In this way, the plant according to the invention has lower energy consumption, a smaller size, and reduced noise.

[0047] Thanks to the fact that the frame (9) of the plant comprises a single inlet for external air and a single outlet for exhausted air and fumes, and that the combustion cell and the heat exchanger are in fluid communication with each other for the passage of fumes from the combustion cell to the heat exchanger, and the fact that the plant comprises a single fan and an air distributor, the plant has reduced energy consumption, is easy to install and maintain, is compact, and has a reduced size.

[0048] The heat exchanger requires a greater quantity of air than the combustion cell. Thanks to the fact that the first duct of the air distributor has a smaller cross-section than the second duct of the air distributor, the air distributor allows a smaller quantity of air to flow to the combustion cell compared to the amount of air that is directed to the heat exchanger. In other words, the ducts and outlets of the air distributor are sized based on the air flow required for the operation of the combustion cell and the heat exchanger.

[0049] Optionally, the ratio between a width of the section of the first duct (71a) of the air distributor and the second duct (72a) of the air distributor is at least 1:10. In this way, the amount of air entering the combustion cell (1) and the heat exchanger (2) depends on the width of the first duct (71a) and the second duct (72a), respectively.

[0050] The fan (6) is adjustable, meaning that it is possible to modify the fan speed, thereby adjusting the flow of incoming external air to the air distributor (7).

[0051] Thanks to the fan and the air distributor (7), it is possible to adjust the quantity of external air: entering the combustion cell (1), which mixes with the gas to become a combustible mixture; entering the heat exchanger (2), which mixes with the fumes from combustion in the combustion cell (1), entering the heat exchanger (2).

[0052] The air distributor (7) can be: of a mechanical type with constant throttling; of a mechanical type with variable geometry; of an electrically / electronically driven type.

[0053] With reference to Figs. 4 and 5, the air distributor (7) of the constant throttling mechanical type is shown.

[0054] This air distributor (7) comprises: the first duct (71a) that conveys external air from the inlet (70) of the air distributor to the first outlet (71) of the air distributor, and the second duct (72a) that conveys external air from the inlet (70) of the air distributor to the second outlet (72) of the air distributor.

[0055] Optionally, the first duct (71a) and the second duct (72a) of the air distributor have axes inclined relative to each other in a "V" shape and inclined with respect to the axis of the inlet (70) of the air distributor.

[0056] It is specified that said air distributor (7) has a fixed external air distribution ratio, dependent on the width of the first duct (71a) and the second duct (72a) of the air distributor and proportional to the fan speed.

[0057] With reference to Fig. 6, a first variant of the air distributor (7) is shown, in which this air distributor (7) is of the constant throttling mechanical type, differing from the air distributor in Figs. 4 and 5 in that the first duct (71a) of the air distributor branches off from the second duct (72a) of the air distributor. The first duct (71a) of the air distributor and the second duct (72a) of the air distributor have axes that are perpendicular to each other, and the axis of the second duct (72a) of the air distributor is coaxial with the inlet (70) of the air distributor.

[0058] With reference to Fig. 7, a second variant of the air distributor (7) is shown, in which said air distributor (7) is of the variable geometry mechanical type, differing from the air distributor in Figs. 4 and 5 in that it comprises a mechanical regulation valve (75), for example of the flap type, arranged on the first outlet (71) of the air distributor. The regulation valve (75) comprises a movable element. Based on a pressure exerted on said movable element by the airflow generated by the fan (6), the regulation valve (75) modifies the quantity of air flowing out of the first outlet (71a).

[0059] Optionally, even though not shown in the figure, the air distributor (7) may comprise a mechanical regulation valve on the second outlet of the air distributor.

[0060] The regulation valve on the first outlet (71) of the air distributor allows: precise modulation towards the combustion cell and broad modulation ranges between maximum and minimum thermal flow; maximum airflow towards the heat exchanger, allowing maximum efficiency of the evaporator of the heat exchanger; a higher minimum fan flow rate.

[0061] With reference to Fig. 8, a third variant of the air distributor (7) is shown, in which this air distributor (7) is of the electrically / electronically driven type, differing from the air distributor in Figs. 4 and 5 in that it comprises an electrically / electronically controlled regulation valve (76), for example of motorized damper type, in the first duct (71a) of the air distributor. The electronic / electronical control of the regulation valve (76) can occur in an open loop or closed loop with a sensor inserted inside the first duct (71a) of the air distributor to detect the air flow passing through the first duct (71a) of the air distributor.

[0062] Optionally, even though not shown in the figure, the air distributor (7) may comprise an electrically / electronically controlled regulation valve in the second duct of the air distributor.

[0063] The regulation valve (76) with electronic control allows direct control of the airflow distribution towards the first and second outlets of the air distributor, and consequently direct control of all the airflows within the plant (100).

[0064] With reference to Fig. 1, the compressor (3) comprises an inlet (30) connected by a pipe to the outlet (22b) of the evaporator of the heat exchanger, and an outlet (31).

[0065] The gas / water exchanger (4) comprises a first inlet (40) connected by a pipe to the outlet (31) of the compressor and a first outlet (41) connected by a pipe to the inlet (22a) of the evaporator of the heat exchanger. The gas / water exchanger (4) also comprises a second inlet (42) connected to the first section (50) of the technical water circuit and a second outlet (43) connected to the technical water circuit (5).

[0066] The technical water circuit (5) comprises a pump (52) arranged in the first section (50) to enable the circulation of the technical water.

[0067] The refrigerant gas, heated in the evaporator (22), and then by the compressor (3), is condensed in the gas / water exchanger (4), releasing heat and consequently heating the technical water in the technical water circuit (5) circulating in the gas / water exchanger (4).

[0068] In this way, the refrigerant gas helps preheat the technical water in the technical water circuit before it reaches the combustion cell (1). Therefore, the combustion cell (1) will need to supply less energy to heat the technical water, reducing gas consumption and CO2 emissions.

[0069] Optionally, a three-way valve (44) is arranged in the first section (50) of the technical water circuit, downstream of the gas / water exchanger (4) and upstream of the water / fumes exchanger (15) of the combustion cell. The three-way valve (44) is connected at the inlet to the second outlet (43) of the gas / water exchanger and at the outlet to the inlet (15a) of the water / fumes exchanger and to the second section (51) of the technical water circuit. In this way, when the water in the technical water circuit reaches the desired temperature at the outlet of the gas / water exchanger (4), the water can be directed directly to the second section (51) of the technical water circuit, avoiding the activation of the combustion cell (1).

[0070] It should be noted that the presence of the three-way valve (44) and the electrically / electronically controlled air distributor (7) is particularly advantageous because it is possible to close the first duct (71a) of the air distributor, preventing air from passing to the combustion cell (1), when the three-way valve (44) prevents the flow of water to the combustion cell (1).

[0071] Optionally, the plant (100) comprises a control unit and sensors connected to the control unit, so that the control unit manages and regulates the activation and deactivation of the fan (6), the air distributor (7), the combustion chamber (1), the compressor (3), the three-way valve (44), and the pump (52). In this way, the control unit manages and regulates the thermal exchange and air flow within the frame (9).

[0072] With reference to Fig. 3, a variant of the plant (100) is shown, which optionally also comprises: a sanitary water circuit (55) comprising a first section (56) designed to be connected via a connection to a return section of a sanitary water plant and a second section (57) designed to be connected via a connection to a supply section of the sanitary water plant; a technical water / sanitary water exchanger (59) comprising a first inlet (59a) connected to the first section (56) of the sanitary water circuit and a first outlet (59b) connected via a pipe to the second section (57) of the sanitary water circuit; the technical water / sanitary water exchanger (59) comprises a second inlet (59c) connected, by a pipe and an additional three-way valve (58), to the second section (51) of the technical water circuit and a second outlet (59d) connected to the first section (50) of the technical water circuit.

[0073] The technical water / sanitary water heat exchanger (59) and the additional three-way valve (58) allow for the heating of sanitary water. The additional three-way valve (58) is designed to divert the flow of technical water, heated through the combustion cell (1), directly to the supply section of the technical water plant or to the technical water / sanitary water exchanger (59) to heat the sanitary water of the sanitary water circuit.

[0074] Although not shown in the figures, alternatively to a single opening, the frame (9) of the plant may comprise two openings that are not in communication with each other, comprising a first opening for the exit of the air-fumes flow from the plant and a second opening designed to allow the entry of external air in the frame of the plant. It should be noted that the frame (9) of the plant comprises at most two openings to separately allow the entry of external air into the frame of the plant and the exit of fumes from the plant. Furthermore, whether there is a single opening or two openings, the air-fumes flow exiting is isolated from the incoming external air flow into the frame (9) of the plant.

[0075] Although not shown in the figures, alternatively, the burner is located outside the chamber of the combustion cell housing the water / fumes exchanger. In this case, the burner is in communication with the chamber of the combustion cell to allow the passage of fumes from the burner to the chamber of the combustion cell.

[0076] Although not shown in the figures, the chamber of the combustion cell housing the water / fumes exchanger and the chamber of the heat exchanger housing the evaporator are formed within a single two-stage component. Optionally, the burner is also arranged within this component, in the chamber of the combustion cell. Alternatively, the burner is positioned outside this component, in communication with the chamber of the combustion cell.

[0077] Modifications or variations of detail within the scope of a person skilled in the art may be made to the present embodiment of the invention, which, however, fall within the scope of the invention as expressed in the appended claims.

Claims

1. Hybrid thermal plant (100) comprising: - a frame (9); - a combustion cell (1), arranged within the frame (9); - a heat exchanger (2), arranged within the frame (9); - a technical water circuit (5) arranged within the frame (9) and designed to be connected to a technical water plant; - a compressor (3), arranged within the frame (9) and connected to the heat exchanger (2); - a gas / water exchanger (4), arranged within the frame (9) and connected to the compressor (3), the heat exchanger (2), and the technical water circuit (5); wherein said combustion cell (1) comprises: - a burner (12) designed to ignite a combustion of external air and gas, generating high-temperature fumes; - a first inlet (12c) for the entry of external air, - a second inlet (12d) intended to be connected to a gas plant for the entry of gas; - a chamber (11) for containing the fumes generated by the burner (12); - a water / fumes exchanger (15) arranged in the chamber (11) of the combustion cell, so that the water / fumes exchanger (15) is externally surrounded by the fumes generated by the burner (12); said water / fumes exchanger (15) being connected to the technical water circuit (5), so that the water / fumes exchanger (15) is traversed by water from the technical water circuit (5); said heat exchanger (2) comprising: - an evaporator (22) arranged in a chamber (21) of the heat exchanger; said evaporator (22) being connected to the compressor (3) and the gas / water exchanger (4) and being designed to be passed through by refrigerant gas; - a first inlet (23) for the entry of external air into the chamber (21) of the heat exchanger; wherein said chamber (11) of the combustion cell and said chamber (21) of the heat exchanger are in fluid communication with each other, so that the fumes generated by the burner (12) surround both the water / fumes exchanger (15) and the evaporator (22) of the heat exchanger; said heat exchanger (2) comprising an outlet (24) for the discharge of an air-fumes flow from the chamber (21) of the heat exchanger; said frame (9) of the plant comprising at least one opening (92) designed to separately allow the entry of external air into the frame (9) of the plant and the exit of the air-fumes flow from the plant (100); said plant (100) comprising: - an air distributor (7) arranged in the frame (9); - a fan (6) arranged in the frame (9) upstream of said air distributor (7), so that said fan (6) is configured to suck in external air and convey said external air inside the air distributor (7); said fan (6) being a single fan; said air distributor (7) being in fluid communication with the fan (6), the first inlet (12c) of the combustion cell, and characterized in that said air distributor is further in fluid communication with the first inlet (23) of the heat exchanger, so that the air distributor (7) is configured to receive external air from the fan (6) and distribute said external air both to the combustion cell (1) and to the heat exchanger (2); said air distributor (7) comprising: - an inlet (70) connected to the fan (6) for the entry of external air into the air distributor (7); - a first duct (71a) ending with a first outlet (71) connected to the first inlet (12c) of the combustion cell; - a second duct (72a) ending with a second outlet (72) connected to the first inlet (23) of the heat exchanger; said first duct (71a) of the air distributor having a smaller section compared to a section of the second duct (72a) of the air distributor.

2. Plant (100) according to claim 1, wherein the ratio between a width of the section of the first duct (71a) of the air distributor and the second duct (72a) of the air distributor is at least 1:10.

3. Plant (100) according to claim 1 or 2, wherein the second outlet (72) of the air distributor (7) is connected to the first inlet (23) of the heat exchanger through a second connecting channel (94) of the plant, to allow external air to flow from the air distributor (7) to the heat exchanger (2).

4. Plant (100) according to anyone of claims from 1 to 3, wherein the air distributor (7) is of mechanical type with constant throttling; said first duct (71a) of the air distributor and the second duct (72a) of the air distributor having axes inclined relative to each other and inclined with respect to an axis of the inlet (70) of the air distributor.

5. Plant (100) according to anyone of claims from 1 to 3, wherein the air distributor (7) is of mechanical type with constant throttling and said first duct (71a) of the air distributor branches off from the second duct (72a) of the air distributor; said first duct (71a) of the air distributor and said second duct (72a) of the air distributor having perpendicular axes relative to each other, and the axis of the second duct (72a) of the air distributor being coaxial with the inlet (70) of the air distributor.

6. Plant (100) according to anyone of claims from 1 to 3, wherein said air distributor (7) is of mechanical type with variable geometry, comprising a mechanical regulation valve (75) arranged on the first outlet (71) of the air distributor.

7. Plant (100) according to claim 6, wherein the air distributor (7) comprises a mechanical regulation valve on the second outlet of the air distributor.

8. Plant (100) according to anyone of claims from 1 to 3, wherein said air distributor (7) is of electrically / electronically driven type, comprising an electrically / electronically controlled regulation valve (76) in the first duct (71a) of the air distributor.

9. Plant (100) according to claim 8, wherein the air distributor (7) comprises an electrically / electronically controlled regulation valve in the second duct of the air distributor.

10. Plant (100) according to anyone of the preceding claims, wherein the combustion cell (1) comprises an outlet (16) for the discharge of fumes from the chamber (11) of the combustion cell and the heat exchanger (2) comprises a second inlet (26) for the entry of fumes into the chamber (21) of the heat exchanger; said plant (100) comprising a first connecting channel (90) connected to the outlet (16) of the combustion cell and the second inlet (26) of the heat exchanger for the passage of the fumes from the chamber (11) of the combustion cell to the chamber (21) of the heat exchanger.

11. Plant (100) according to anyone of the preceding claims, wherein a three-way valve (44) is arranged in the first section (50) of the technical water circuit, downstream of the gas / water exchanger (4) and upstream of the water / fumes exchanger (15) of the combustion cell; said three-way valve (44) being connected at the inlet to the gas / water exchanger (4) and at the outlet to the water / fumes exchanger (15) and to the second section (51) of the technical water circuit.

12. Plant (100) according to anyone of the preceding claims, wherein said plant (100) comprises a single outlet channel (91) connected to the outlet (24) of the heat exchanger for the discharge of the air-fumes flow from the plant (100).

13. Plant (100) according to claim 12, wherein the outlet channel (91) of the plant passes through the opening (92) of the frame of the plant (100); said outlet channel (91) of the plant having a smaller size than the opening (92) of the frame of the plant, so that there is a gap between edges of said opening (92) and said outlet channel (91) for the entry of air into the frame (9) of the plant from the outside.

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