Multifunctional thermal plant, comprising a heat pump with a reduced amount of refrigerant

Abstract

The invention relates to a thermal installation (10) comprising: external and internal fluid flows (24, 28); and a heat pump (20) comprising a first refrigerant circuit (40), a first compressor (44), and first external (48) and internal (50) heat exchangers, enabling heat exchange between the refrigerant and, respectively, the external fluid flow (24) and the internal fluid flow (28). The heat pump further comprises: a second refrigerant circuit (42), separate from the first circuit (40); and a second compressor (56) and second external (58) and internal (60) heat exchangers, enabling heat exchange between the refrigerant and, respectively, the external fluid flow and the internal fluid flow.

Description

[0001] The present invention relates to a thermal installation of the type comprising: an external fluid flow and an internal fluid flow, distinct from each other; and a heat pump; said heat pump comprising: a first refrigerant circuit; and a first compressor, a condenser, a first external heat exchanger, a first internal heat exchanger, a first expansion valve and a first connection device, arranged on said first circuit; the heat pump being capable of imposing a higher pressure on the refrigerant of the first circuit downstream of the first compressor than upstream of said first compressor; each of the first external and internal heat exchangers allowing heat exchange between the refrigerant and, respectively, the external fluid flow and the internal fluid flow;the installation being configured so that, in a first configuration of the first connection device, the downstream of the first compressor is connected to the condenser, to allow the refrigerant of the first circuit to release energy to said condenser; and the first expansion valve is arranged upstream of the first external heat exchanger, to allow the refrigerant of the first circuit to draw energy from the external fluid flow.

[0002] The invention is particularly applicable to thermal installations for residential buildings.

[0003] In single-family homes, it is common practice to install heating systems equipped with heat pumps, particularly for regulating the building's temperature and providing domestic hot water. Heat pumps can reduce energy consumption by a factor of three to four compared to fossil fuel heating systems such as gas or oil boilers. Furthermore, using heat pumps reduces the building's carbon footprint.

[0004] Typically, heat pump systems use a fluorinated refrigerant, such as HFC-134a. These compounds allow for refrigerant charges exceeding 1 kg, making them suitable for large-volume circuits. However, fluorinated compounds have a significant environmental impact, as measured by their global warming potential (GWP).

[0005] Other refrigerants, such as hydrocarbons like isobutane or propane, have a much lower GWP (Global Warming Potential). However, these compounds typically exhibit toxicity or flammability. These constraints limit the maximum charge in a circuit to a small quantity, typically around 150 g, in installations without minimum surface area or ventilation requirements. Such operating conditions make non-fluorinated compounds unsuitable for large refrigerant circuit volumes.

[0006] It is therefore advantageous to design heat pumps for thermal installations so that they require only a reduced quantity of refrigerant. Such a thermal installation is described in particular in document FR3124586 on behalf of the Applicant.

[0007] Furthermore, in order to optimize the thermal regulation of the building, it is advantageous to have a reversible heat pump, allowing the indoor air to be heated or cooled as needed.

[0008] The present invention aims to provide a thermal installation capable of performing several functions, such as domestic heating, air conditioning and domestic hot water heating, while requiring a reduced quantity of refrigerant.

[0009] To this end, the invention relates to a thermal installation of the aforementioned type, in which: the heat pump further comprises: a second refrigerant circuit, separate from the first circuit; and a second compressor, a second external heat exchanger, a second internal heat exchanger, a second expansion valve and a second connection device, arranged on said second circuit; the heat pump being capable of imposing a higher pressure on the refrigerant of the second circuit downstream of the second compressor than upstream of said second compressor; each of the second external and internal heat exchangers allowing heat exchange between the refrigerant and, respectively, the external fluid flow and the internal fluid flow;and - the installation is configured so that, in a first configuration of the second connection device, the downstream of the second compressor is connected to the second external heat exchanger, to allow the refrigerant of the second circuit to transfer energy to the external fluid flow.;

[0010] According to other advantageous aspects of the invention, the thermal installation comprises one or more of the following characteristics, taken individually or in all technically possible combinations: The thermal installation is configured so that the second external heat exchanger is located downstream of the first external heat exchanger with respect to the external fluid flow; the thermal installation is configured so that, in a second configuration of the first connection device, the downstream of the first compressor is connected to the first internal heat exchanger to allow the refrigerant to transfer energy to the internal fluid flow; and the first expansion valve is located upstream of the first external heat exchanger, to allow the refrigerant of the first circuit to draw energy from the external fluid flow; In the first configuration of the first connection device, the first internal heat exchanger is connected upstream of the first compressor, so as to be subjected to a low pressure from said first compressor; and in the second configuration of the first connection device, the condenser is connected upstream of said first compressor; the first and second internal heat exchangers are arranged in series with respect to the internal airflow; the first connection device includes a first four-way valve; and in the first and second configurations of said first connection device, said first four-way valve is respectively in a first and a second position;The thermal installation is configured so that, in a second configuration of the second connection device, the downstream of the second compressor is connected to the second indoor heat exchanger, to allow the refrigerant of the second circuit to transfer energy to the indoor fluid flow; in the first configuration of the second connection device, the second expansion valve is arranged upstream of the second indoor heat exchanger, to allow the refrigerant of the second circuit to draw energy from the indoor fluid flow; and in the second configuration of the second connection device, the second expansion valve is arranged upstream of the second outdoor heat exchanger, to allow the refrigerant of the second circuit to draw energy from the outdoor fluid flow; the second connection device includes a second four-way valve;and in the first and second configurations of said second connection device, said second four-way valve is respectively in a first and a second position; the second compressor is a variable speed compressor; the thermal installation further comprises: a domestic hot water circuit, including in particular a tank in thermal contact with the condenser; and an electric heating element suitable for heating the water received in said tank.

[0011] The invention further relates to a first method of operating a thermal installation as described above, in which each of the first and second connection devices is in its first configuration.

[0012] According to a preferred embodiment of said first process, the flow of external fluid and a speed of the second compressor are regulated so that a temperature of the external fluid at the outlet of the second external heat exchanger is equal to a temperature of said external fluid at the inlet of the first external heat exchanger.

[0013] According to a preferred embodiment of said first process, when an outside temperature is above a first threshold, a domestic hot water temperature setpoint is lowered and an indoor air temperature setpoint is raised during a night period, compared to setpoint values ​​during a day period.

[0014] The invention further relates to a second method of operating a thermal installation as described above, in which each of the first and second connection devices is in its second configuration.

[0015] According to a preferred embodiment of said second process, when an outside temperature is below a second threshold, a domestic hot water temperature setpoint is raised and an indoor air temperature setpoint is lowered during a night period, compared to setpoint values ​​during a day period.

[0016] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which: there figure 1 is a schematic representation of a thermal installation according to an embodiment of the invention, in a first configuration; the figure 2 is a schematic representation of the thermal installation of the figure 1 , in a second configuration; and the figure 3 is a schematic, cross-sectional view of an element of the thermal installation of figures 1 And 2 .

[0017] THE figures 1 And 2 show a thermal installation 10 according to an embodiment of the invention.

[0018] The thermal installation 10 is integrated into a building 12, for example a dwelling.

[0019] The heating system 10 comprises: an external assembly 14; an internal assembly 16; a domestic hot water circuit 18; and a heat pump 20. In the embodiment shown, the heating system 10 also includes an auxiliary electric heating element 22.

[0020] The external arrangement 14 is capable of generating a flow 24 of external fluid, flowing outside the building 12. In the embodiment shown, the external fluid is the air outside the building 12; and the external arrangement 14 includes an external fan 26 capable of generating the flow 24 of outside air.

[0021] The interior arrangement 16 is capable of generating an internal fluid flow 28, flowing inside the building 12. In the embodiment shown, the internal fluid is the air inside the building 12; and the interior arrangement 16 includes an internal fan 30 capable of generating the internal air flow 28. Optionally, the interior arrangement 16 includes a solid particle filter 32.

[0022] In an alternative not shown, the internal fluid is a water loop flowing inside building 12.

[0023] The domestic hot water circuit 18 is intended to supply building 12 with domestic hot water. This circuit 18 includes, in particular: a domestic hot water storage tank 34; and a water inlet and outlet opening onto said tank. In the embodiment shown, the auxiliary electric heating element 22 is in thermal contact with the water in the tank 34.

[0024] The heat pump 20 is intended to provide both thermal regulation and domestic hot water heating for building 12.

[0025] The heat pump 20 has a first 40 and a second 42 refrigerant circuits, separate from each other. More specifically, the heat pump 20 is configured so that the refrigerant in the first circuit 40 and the refrigerant in the second circuit 42 do not mix.

[0026] The heat pump 20 further comprises: a first compressor 44, a condenser 46, a first external heat exchanger 48, a first internal heat exchanger 50, a first expansion valve 52 and a first connection device 54, arranged on said first circuit 40.

[0027] The heat pump 20 also includes: a second compressor 56, a second external heat exchanger 58, a second internal heat exchanger 60, a second expansion valve 62 and a second connection device 64, arranged on the second circuit 42.

[0028] The heat pump 20 also includes an electronic control module 66. Preferably, the heat pump 20 also includes one or more temperature and / or pressure sensors (not shown), connected to said electronic module 66. Said sensors are in particular located on the first 40 and second 42 refrigerant circuits and / or on the outdoor and indoor fluid flows 24, 28 and / or in the domestic hot water tank 34.

[0029] The first refrigerant circuit 40 comprises several branches connected by junctions. In particular, the first refrigerant circuit 40 includes a first 68 and a second 70 junctions known as "T-junctions". A T-junction is defined as a junction joining three branches of the first circuit 40.

[0030] The first compressor 44 is capable of compressing the refrigerant of the first circuit 40, so as to determine a direction of circulation of said refrigerant.

[0031] More specifically, the first compressor 44 is considered to be located on the first circuit 40 between a first upstream point 72 and a first downstream point 74. When said first compressor 44 is in operation, low-pressure gaseous refrigerant enters said first compressor at the first upstream point 72 and exits at high pressure at the first downstream point 74.

[0032] The first upstream point 72, i.e. the low pressure side of the first compressor 44, is connected to the first T-junction 68 of the first circuit 40.

[0033] In the embodiment shown, the first compressor 44 is a fixed speed compressor.

[0034] The condenser 46 is positioned in thermal contact with the domestic hot water tank 34, so as to transfer heat to the domestic hot water. The condenser 46 is preferably designed with a reduced internal volume to require only a small quantity of refrigerant. For example, it is a condenser such as the one described in document FR2963416 on behalf of the Applicant.

[0035] On the first refrigerant circuit 40, one end of the condenser 46 is connected to the second T-junction 70.

[0036] The first external heat exchanger 48 is located on the external fluid stream 24. In the embodiment shown, the first external heat exchanger 48 is an air / refrigerant heat exchanger, located on the external air stream 24.

[0037] On the first refrigerant circuit 40, the ends of the first external heat exchanger 48 are connected respectively to the first 68 and the second 70 T-junctions.

[0038] The first internal heat exchanger 50 is located on the internal fluid stream 28. In the embodiment shown, the first internal heat exchanger 50 is an air / refrigerant heat exchanger, located on the internal air stream 28.

[0039] On the first refrigerant circuit 40, one end of the first internal heat exchanger 50 is connected to the second T-junction 70.

[0040] As detailed below, each of the first external heat exchangers 48 and internal heat exchangers 50 is a reversible heat exchanger, capable of operating in condenser mode or evaporator mode.

[0041] Preferably, the first external heat exchangers 48 and internal heat exchangers 50 are designed with a reduced internal volume to require only a small amount of refrigerant.

[0042] The first expansion valve 52 is located between the first external heat exchanger 48 and the second T-junction 70.

[0043] The first connection device 54 includes a first four-way valve 76. Preferably, the first connection device 54 also includes non-return valves 78, 80.

[0044] The first four-way valve 76 is connected to the downstream 74 of the first compressor 44, to a second end of the condenser 46, to the first T-junction 68 and to a second end of the first internal heat exchanger 50.

[0045] A first non-return valve 78 is arranged between the first end of the condenser 46 and the second T-junction 70. A second non-return valve 80 is arranged between the first end of the first internal heat exchanger 50 and the second T-junction 70. Each of the valves 78, 80 prevents the circulation of fluid from said second junction 70.

[0046] The second compressor 56 is capable of compressing the refrigerant of the second circuit 42, so as to determine a direction of circulation of said refrigerant.

[0047] More specifically, the second compressor 56 is considered to be located on the second circuit 42 between a second upstream point 82 and a second downstream point 84. When said second compressor 56 is in operation, low-pressure gaseous refrigerant enters said second compressor at the second upstream point 82 and exits at high pressure at the second downstream point 84.

[0048] Preferably, the second compressor 56 is a variable speed compressor, in particular an inverter type compressor.

[0049] The second external heat exchanger 58 is located on the external fluid stream 24. In the embodiment shown, the second external heat exchanger 58 is an air / refrigerant heat exchanger, located on the external air stream 24.

[0050] Preferably, on the outside air flow 24, the first 48 and second 58 external heat exchangers are arranged in series. More preferably, the second external heat exchanger 58 is arranged downstream of the first external heat exchanger 48.

[0051] The second internal heat exchanger 60 is located on the internal fluid stream 28. In the embodiment shown, the second internal heat exchanger 60 is an air / refrigerant heat exchanger, located on the internal air stream 28.

[0052] Preferably, the first 50 and second 60 internal heat exchangers are arranged in series with respect to the internal airflow 28. Such an arrangement allows for maximum utilization of the two compressors 44 and 56.

[0053] In the embodiment shown, on the indoor air flow 28, the second indoor heat exchanger 60 is arranged upstream of the first indoor heat exchanger 50. In an alternative not shown, the second indoor heat exchanger 60 is arranged downstream of the first indoor heat exchanger 50.

[0054] Preferably, filter 32 is positioned upstream of the first 50 and second 60 internal heat exchangers, relative to the internal air flow 28.

[0055] As detailed below, each of the second external heat exchangers 58 and internal heat exchangers 60 is a reversible heat exchanger, capable of operating in condenser mode or evaporator mode.

[0056] Preferably, the second external heat exchangers 58 and internal heat exchangers 60 are designed with a reduced internal volume to require only a small amount of refrigerant.

[0057] The second expansion valve 62 is located between the second external heat exchanger 58 and the second internal heat exchanger 60.

[0058] The second connection device 64 includes a second four-way valve 86. This second valve 86 is connected to the upstream 82 and downstream 84 of the second compressor 56 and to the second external 58 and internal 60 heat exchangers.

[0059] The electronic control module 66 is in communication with the outdoor fan 26 and indoor fan 30, with the first 44 and second 56 compressors and with the first 76 and second 86 four-way valves.

[0060] Preferably, the second expansion valve 62 is an electronic expansion valve, also communicating with the electronic control module 66. Such an electronic expansion valve allows for better adaptation to power variations in the second circuit 42, induced by the second variable-speed compressor 56.

[0061] On the figure 1 The first four-way valve 76 is in a first position. In said first position of the first valve 76, the downstream 74 of the first compressor 44 is connected to the second end of the condenser 46; and the first T-junction 68 is connected to the first internal heat exchanger 50.

[0062] On the figure 2 The first four-way valve 76 is in a second position. In said second position of the first valve 76, the downstream 74 of the first compressor 44 is connected to the first internal heat exchanger 50; and the second end of the condenser 46 is connected to the first T-junction 68.

[0063] On the figure 1 The second four-way valve 86 is in a first position. In said first position of the second valve 86, the downstream 84 of the second compressor 56 is connected to the second external heat exchanger 58; and the second internal heat exchanger 60 is connected to the upstream 82 of said second compressor 56.

[0064] On the figure 2 The second four-way valve 86 is in a second position. In said second position of the second valve 86, the downstream 84 of the second compressor 56 is connected to the second internal heat exchanger 60; and the second external heat exchanger 58 is connected to the upstream 82 of said second compressor 56.

[0065] There figure 3 represents a preferred embodiment of the first 48 and second 58 external heat exchangers.

[0066] In the said preferred embodiment, the heat pump 20 includes an exchanger block 90. ​​An orthonormal basis (X, Y, Z) is considered associated with said exchanger block 90.

[0067] The exchanger block 90 is an air / refrigerant exchanger, intended to be traversed by the flow 24 of outside air, said flow 24 moving parallel to the direction X.

[0068] The heat exchanger block 90 comprises a first 92 and a second 94 refrigerant circuits. These first 92 and second 94 circuits are arranged respectively on the first 40 and second 42 refrigerant circuits. The heat exchanger block 90 thus forms the first 48 and second 58 external heat exchangers, configured as a single unit.

[0069] The heat exchanger block 90 is configured so that the second network 94 is located downstream of the first network 92 with respect to the outside air flow 24. As indicated above, the second outdoor heat exchanger 58 is located downstream of the first outdoor heat exchanger 48 with respect to said flow 24.

[0070] In the embodiment shown, the exchanger block 90 comprises: a plurality of fins 96; a plurality of first 98 and second 99 tubes; and a plurality of first 100 and second 101 connections.

[0071] The fins 96 are configured to facilitate heat exchange with the outside airflow 24. In the embodiment shown, the fins 96 are parallel to each other and arranged in (X, Z) planes. Only one fin 96 is visible in the cross-sectional view of the figure 3 .

[0072] Each tube 98, 99 passes through the fins 96 and extends between two ends. In the embodiment shown, the tubes 98, 99 are parallel to each other and to the Y direction.

[0073] Each tube 98, 99 is configured to receive circulating refrigerant. The fins 96 and the tubes 98, 99 are designed to facilitate heat exchange between said refrigerant and the outside air flow 24.

[0074] The first tubes 98 are included in the first network 92 and the second tubes 99 are included in the second network 94. In the embodiment shown, the first tubes 98 are arranged upstream of the second tubes 99 with respect to the outside air flow 24.

[0075] The first connections 100 are arranged at the ends of the first tubes 98, so as to form the first network 92. The first tubes 98 are connected in series and / or in parallel by the first connections 100. In the embodiment shown, the first network 92 has three parallel branches, arranged on the first refrigerant circuit 40 and forming the first external heat exchanger 48.

[0076] The second connections 101 are arranged at the ends of the second pipes 99, so as to form the second network 94. The second pipes 99 are connected in series and / or in parallel by the second connections 101. In the embodiment shown, the second network 94 has two parallel branches, arranged on the second refrigerant circuit 42 and forming the second external heat exchanger 58.

[0077] Preferably, the first 50 and second 60 internal heat exchangers are formed as a single unit, by an exchanger block similar to the exchanger block 90. ​​Such an exchanger block allows the formation of heat exchangers with a reduced internal volume, requiring only a small quantity of refrigerant.

[0078] On the figures 1 And 2 The high-pressure zones of circuits 40 and 42 of the heat pump 20 are represented by solid lines, and the low-pressure zones of said circuits 40 and 42 are represented by dashed lines. These high- and low-pressure zones depend on the operating modes of said circuits 40 and 42 described below.

[0079] A first operating mode of the first circuit 40 allows the production of domestic hot water by extracting heat from the outside air of the building 12. For this purpose, the first four-way valve 76 is in the first position of the figure 1 .

[0080] In the first operating mode of the first circuit 40, the first operating compressor 44 sends gaseous refrigerant, under high pressure, to the first four-way valve 76. This first valve directs the refrigerant to the condenser 46. The refrigerant then transfers heat to the water in the tank 34 by condensing into a liquid state.

[0081] The refrigerant then reaches the first expansion valve 52 via the second junction 70, and its pressure drops. The fluid then passes through the first external heat exchanger 48. This first heat exchanger operates in evaporative mode, with the refrigerant absorbing heat from the outside air as it changes to a gaseous state.

[0082] The fluid in a low-pressure gaseous state then joins the upstream 72 of the first compressor 44 via the first junction 68.

[0083] Furthermore, in the first operating mode of the first circuit 40, the first internal heat exchanger 50 is subjected to the low pressure of the first compressor 44 via the first junction 68. The residual refrigerant in the first internal heat exchanger 50 is therefore in a gaseous state, which minimizes its quantity.

[0084] A second operating mode of the first circuit 40 of the heat pump 20 allows the interior air of the building 12 to be heated by extracting heat from the outside air. For this purpose, the first four-way valve 76 is in the second position of the figure 2 .

[0085] In the second operating mode of the first circuit 40, the high-pressure gaseous refrigerant is directed to the first indoor heat exchanger 50 by the first four-way valve 76. This first indoor heat exchanger 50 operates in condenser mode, with the refrigerant transferring heat to the indoor airflow 28 while condensing.

[0086] The refrigerant then passes through the second junction 70 and is sent to the first expansion valve 52, where its pressure drops. It then passes through the first external heat exchanger 48 in evaporative mode. The refrigerant evaporates, absorbing heat from the outside air stream 24. The low-pressure gaseous refrigerant then returns to the upstream side 72 of the first compressor 44 by passing through the first junction 68.

[0087] Furthermore, in the second operating mode of the first circuit 40, the condenser 46 is subjected to the low pressure of the first compressor 44 via the first junction 68. The residual refrigerant in the condenser 46 is therefore in a gaseous state, which minimizes its quantity.

[0088] Each operating mode of the first refrigerant circuit 40 thus allows the unused part of said first circuit to be isolated and emptied via the check valves 78, 80 and by the appropriate position of the four-way valve 76.

[0089] A first operating mode of the second circuit 42 of the heat pump 20 allows the indoor air of the building 12 to be cooled by transferring heat to the outdoor air. For this purpose, the second four-way valve 86 is in the first position of the figure 1 .

[0090] In the first operating mode of the second circuit 42, the second compressor 56, when running, sends gaseous refrigerant under high pressure to the second four-way valve 86. This second valve directs the refrigerant to the second outdoor heat exchanger 58 in condensing mode. The refrigerant in the second circuit 42 condenses, releasing heat to the outside air stream 24.

[0091] The refrigerant is then sent to the second expansion valve 62, where its pressure drops, and then it passes through the second internal heat exchanger 60. This second heat exchanger then operates in evaporative mode, with the refrigerant absorbing heat from the internal air stream 28 while evaporating. The low-pressure gaseous refrigerant then enters the upstream side 82 of the second compressor 56 via the second four-way valve 86.

[0092] A second operating mode of the second circuit 42 of the heat pump 20 allows the interior air of the building 12 to be heated by extracting heat from the outside air. For this purpose, the second four-way valve 86 is in the second position of the figure 2 .

[0093] In the second operating mode of the second circuit 42, the high-pressure gaseous refrigerant is directed to the second indoor heat exchanger 60 by the second four-way valve 86. This second indoor heat exchanger 60 then operates in condenser mode, with the refrigerant transferring heat to the indoor airflow 28 while condensing.

[0094] The refrigerant is then sent to the second expansion valve 62, where its pressure decreases. It then passes through the second external heat exchanger 58 in evaporative mode. The refrigerant evaporates, absorbing heat from the outside air stream 24. The low-pressure gaseous refrigerant then enters the upstream side 82 of the second compressor 56 via the second four-way valve 86.

[0095] The operating procedures of installation 10 will now be described. Each of these procedures is implemented by a program stored in the electronic module 66.

[0096] A first operating method of the installation 10 will now be described. The first method cools the indoor air of the building 12 while simultaneously producing domestic hot water. For this purpose, each of the first 40 and second 42 circuits of the heat pump 20 is in its first operating mode described above. More specifically, each of the first 76 and second 86 four-way valves is in its first position of the figure 1 .

[0097] There figure 3 schematically shows a temperature variation of the outside air flow 24 in the context of the first process.

[0098] At a temperature T1, the outside air flow 24 arrives at the inlet of the first external heat exchanger 48 in evaporator mode. The outside air transfers energy to the refrigerant of the first circuit 40; the outside air flow 24 exits said first external heat exchanger 48 with a temperature Tmin, lower than T1.

[0099] The flow 24 continues its path by passing through the second external heat exchanger 58 in condenser mode. The outside air receives energy from the refrigerant of the second circuit 42; the outside air flow 24 exits said second external heat exchanger 58 with a temperature T2, greater than Tmin.

[0100] Thus, to cool the indoor air of building 12, the second circuit 42 benefits from outdoor air cooled by the first circuit 40, which improves the performance of the heat pump 20.

[0101] According to a preferred mode of the first process, the electronic module 66 regulates the speeds of the outdoor fan 26 and the second variable-speed compressor 56, so that T2 equals T1. According to this preferred mode of the first process, the energy extracted from the outside air by the heat pump 20 is therefore zero. In other words, the energy used to produce the domestic hot water for the system 10 is entirely extracted from the indoor airflow 28 of the building 12, which is thus cooled.

[0102] According to a preferred mode of the first process, when the outside temperature of building 12 is high (particularly in summer), the electronic module 66 promotes the production of domestic hot water during the day, in order to cool the indoor air of building 12 by means of cooled outdoor air as described above.

[0103] For example, when the outside temperature of building 12 is above a first threshold, stored in the electronic module 66, a domestic hot water temperature setpoint is lowered and an indoor air temperature setpoint is raised during a night period as defined in said electronic module 66. The production of domestic hot water and the cooling of the indoor air are thus favoured during the day.

[0104] A second operating method for the installation 10, which heats the indoor air of the building 12, will now be described. Each of the first 40 and second 42 circuits of the heat pump 20 is in its second operating mode described above. More specifically, each of the first 76 and second 86 four-way valves is in its second position of the figure 2 .

[0105] The first 48 and second 58 external heat exchangers are arranged in series to extract heat from the outside air flow 24. Similarly, the first 50 and second 60 internal heat exchangers are arranged in series to transfer heat to the inside air flow 28.

[0106] If there is no need for domestic hot water production, the second process provides significant heating power, allowing the indoor air to quickly reach the desired heating temperature. The second variable-speed compressor 56 regulates the heating power according to demand.

[0107] According to a preferred mode of the second process, when the outside temperature of the building 12 is low (particularly in winter), the electronic module 66 promotes the production of domestic hot water during the night, so as to leave the first compressor 44 available during the day for heating the indoor air.

[0108] For example, when the outside temperature of building 12 is below a second threshold, stored in the electronic module 66, a domestic hot water temperature setpoint is raised and an indoor air temperature setpoint is lowered during the night period as defined in said electronic module 66. The production of domestic hot water is thus favoured during the night.

[0109] A third operating method for the installation 10 will now be described. Preferably, such a method is implemented temporarily, in the event of a failure of the second circuit 42 and / or the second compressor 56.

[0110] According to the third method, the heating of the indoor airflow 28 is provided by the first circuit 40, in its second operating mode described above. Furthermore, domestic hot water production is provided by the auxiliary electric heating element 22.

[0111] Before any repair work is carried out on installation 10, the third process ensures a minimum acceptable temperature for the indoor air flow 28, without a shortage of domestic hot water.

[0112] The configuration of system 10 minimizes the amount of refrigerant required for its operation. Specifically, system 10 can be sized to operate with a propane (R290) charge of 150 g or less per circuit 40, 42. Therefore, a building 12 can be equipped with system 10 without any constraints regarding the building's surface area or ventilation, and with a low environmental impact.

[0113] Furthermore, installation 10 allows combining an air conditioning function with heating and domestic hot water functions, for better thermal comfort of building 12.

Claims

1. Thermal installation (10) comprising: an external fluid flow (24) and an internal fluid flow (28), separate from each other; a domestic hot water tank (34); and a heat pump (20); said heat pump comprising: - a first refrigerant circuit (40); and - a first compressor (44), a condenser (46), a first external heat exchanger (48), a first internal heat exchanger (50), a first expansion valve (52) and a first connection device (54), arranged on said first circuit; the condenser (46) being arranged in thermal contact with the domestic hot water tank (34); the heat pump being capable of imposing a higher pressure on the refrigerant of the first circuit downstream (74) of the first compressor than upstream (72) of said first compressor;each of the first external (48) and internal (50) heat exchangers allowing heat exchange between the refrigerant and, respectively, the external fluid flow (24) and the internal fluid flow (28); the installation being configured such that, in a first configuration of the first connection device (54), the downstream (74) of the first compressor (44) is connected to the condenser (46); and the first expansion valve (52) is disposed upstream of the first external heat exchanger (48); the installation being; characterized in that- the heat pump (20) further comprises: a second refrigerant circuit (42), separate from the first circuit (40); and a second compressor (56), a second external heat exchanger (58), a second internal heat exchanger (60), a second expansion valve (62) and a second connection device (64), arranged on said second circuit; the heat pump being capable of imposing a higher pressure on the refrigerant of the second circuit downstream (84) of the second compressor (56) than upstream (82) of said second compressor; each of the second external (58) and internal (60) heat exchangers allowing heat exchange between the refrigerant and, respectively, the external fluid flow and the internal fluid flow;and - the installation is configured so that, in a first configuration of the second connection device (64), the downstream (84) of the second compressor (56) is connected to the second external heat exchanger (58).; 2. Thermal installation (10) according to claim 1, configured so that the second external heat exchanger (58) is disposed downstream of the first external heat exchanger (48) with respect to the flow (24) of external fluid.

3. Thermal installation (10) according to claim 1 or 2, configured so that, in a second configuration of the first connection device (54), the downstream of the first compressor (44) is connected to the first internal heat exchanger (50); and the first expansion valve (52) is arranged upstream of the first external heat exchanger (48).

4. Thermal installation according to any one of the preceding claims, wherein, in the first configuration of the first connection device (54), the first internal heat exchanger (50) is connected upstream of the first compressor (44); and in the second configuration of the first connection device (54), the condenser (46) is connected upstream of said first compressor (44).

5. Thermal installation according to any one of the preceding claims, wherein the first (50) and second (60) internal heat exchangers are arranged in series with respect to the internal airflow (28).

6. Thermal installation according to any one of the preceding claims, wherein: the first connection device (54) comprises a first four-way valve (76); and in the first and second configurations of said first connection device, said first four-way valve is respectively in a first and a second position.

7. Thermal installation according to any one of the preceding claims, configured such that, in a second configuration of the second connection device (64), the downstream of the second compressor (56) is connected to the second internal heat exchanger (60).

8. Thermal installation according to claim 7, wherein, in the first configuration of the second connection device (64), the second expansion valve (62) is disposed upstream of the second internal heat exchanger (60); and in the second configuration of the second connection device (64), the second expansion valve (62) is disposed upstream of the second external heat exchanger (58).

9. Thermal installation according to any one of claims 6 or 7, wherein: the second connection device (64) comprises a second four-way valve (86); and in the first and second configurations of said second connection device, said second four-way valve is respectively in a first and a second position.

10. Thermal installation (10) according to any one of the preceding claims, wherein the second compressor (56) is a variable speed compressor.

11. Method of operating a thermal installation (10) according to claim 10, wherein: each of the first (54) and second (64) connection devices is in its first configuration; and the flow (24) of external fluid and a speed of the second compressor (56) are regulated so that a temperature (T2) of the external fluid at the outlet of the second external heat exchanger (58) is equal to a temperature (T1) of said external fluid at the inlet of the first external heat exchanger (48).

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