HEAT PUMP AND METHOD FOR INSTALLING THE SAME

Abstract

A heat pump including a refrigerant circuit configured to circulate flammable refrigerant, and an indoor unit configured to be arranged in an indoor space. The refrigerant circuit has a compressor, a utilisation-side heat exchanger, an expansion device and a heat-source-side heat exchanger connected by piping. The an indoor unit includes an outer casing having a top, and a sealed container accommodated in the outer casing. The sealed container has a bottom and a top and accommodates at least one of the compressor, the utilisation-side heat exchanger, the expansion device, and the heat-source-side heat exchanger. The sealed container has a release opening to exhaust leaking refrigerant to an exterior of the outer casing of the indoor unit.

Claims

1. A heat pump, comprising: a refrigerant circuit configured to circulate flammable refrigerant, the refrigerant circuit having a compressor, a utilisation-side heat exchanger, an expansion device and a heat-source-side heat exchanger connected by piping; and an indoor unit configured to be arranged in an indoor space, the indoor unit including an outer casing having a top, and a sealed container accommodated in the outer casing, the sealed container having a bottom and a top and accommodating at least one of the compressor, the utilisation-side heat exchanger, the expansion device, and the heat-source-side heat exchanger, the sealed container having a release opening to exhaust leaking refrigerant to an exterior of the outer casing of the indoor unit.

2. The heat pump according to claim 1, wherein the release opening is arranged in the top of the sealed container, and the sealed container protrudes through the top of the outer casing of the indoor unit.

3. The heat pump according to claim 1, wherein the sealed container includes a chimney having a first end and a second end, the first end of the chimney is in fluid communication with an interior of the sealed container, and the release opening of the sealed container is arranged at the second end of the chimney.

4. The heat pump according to claim 3, wherein the release opening is positioned further away from the bottom than the top of the sealed container to exhaust leaking refrigerant into the indoor space.

5. The heat pump according to claim 4, wherein the release opening is positioned above the top of the outer casing.

6. The heat pump according to claim 1, wherein the utilisation-side heat exchanger is accommodated in the sealed container.

7. The heat pump according to claim 1, wherein the refrigerant circuit is accommodated in the sealed container, and the sealed container is the outer casing.

8. The heat pump according to claim 1, wherein a connection of the at least one of the compressor, the utilisation-side heat exchanger, the expansion device, and the heat-source-side heat exchanger, which is accommodated in the sealed container, with the piping is accommodated in the sealed container.

9. The heat pump according to claim 1, wherein one of the release opening is situated at least 1.8 m above a ground of the indoor space, when the outer casing of the indoor unit is installed, and the release opening is situated below 1.8 m relative to the ground of the indoor space when the outer casing of the indoor unit is installed, and a fan is provided in order to at least circulate air in the indoor space.

10. The heat pump according to claim 1, wherein the release opening is situated at a height H above a ground of the indoor space when the outer casing of the indoor unit is installed, the height H being at least a higher result of $H\ge \frac{mc}{35\star {\mathrm{LFL}}^{\frac{5}{4}}}\mathrm{OR}H\ge \frac{mc}{150\star \mathrm{LFL}}$ such that the height H reflects a minimum height of the release opening measured from the ground of the indoor space, mc reflects a mass of the refrigerant in the refrigerant circuit, and LFL reflects a low flammability level coefficient.

11. The heat pump according to claim 1, wherein an accumulation of all openings in the sealed container, other than the release opening, having a single dimension of more than 0.1 mm and communicating the interior of the sealed container with an exterior environment of the sealed container, is smaller than 5 cm.sup.2, and openings in the sealed container, other than the release opening, having a single dimension of not more than 0.1 mm are not considered as openings through which leaking refrigerant can escape.

12. The heat pump according to claim 1, wherein the sealed container is an airtight container.

13. The heat pump according to claim 1, wherein piping connecting to at least one of the compressor, the utilisation-side heat exchanger, the expansion device, and the heat-source-side heat exchanger, which is accommodated in the sealed container, passes through the release opening to the remainder of the refrigerant circuit.

14. The heat pump according claim 1, wherein at least one of the refrigerant circuit contains the flammable refrigerant, and the refrigerant consists of R32 or includes R32.

15. A method of installing the heat pump according to claim 1, the method comprising: installing the outer casing of the indoor unit of the heat pump in the indoor space, the release opening of the sealed container being arranged at least 1.8 m above the ground of the indoor space.

16. A method of installing the heat pump according to claim 1, the method comprising: installing the outer casing of the indoor unit of the heat pump in the indoor space, a fan being provided in the indoor space to at least circulate air in the indoor space, and the release opening of the sealed container being arranged below 1.8 m above the ground of the indoor space.

17. A method of installing the heat pump according to claim 1, the method comprising: installing the outer casing of the indoor unit of the heat pump in the indoor space, the release opening of the sealed container being arranged at a height H above a ground of the indoor space when the outer casing of the indoor unit is installed, the height H being at least a higher result of $H\ge \frac{mc}{2.5\star {\mathrm{LFL}}^{\frac{5}{4}}\star A^{\frac{1}{2}}}\mathrm{OR}H\ge \frac{mc}{\mathrm{SF}\star \mathrm{LFL}\star A}$ such that the height H reflects a minimum height of the release opening measured from the ground of the indoor space, mc reflects a mass of the refrigerant in the refrigerant circuit, LFL reflects a lower flammability limit, SF reflects a safety factor, SF is 0.75, and A represents an area of the indoor space.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0067] FIG. 1 shows an overall structure of an indoor unit of a heat pump according to the present invention.

[0068] FIG. 2 shows the overall structure of the indoor unit of FIG. 1 with the outer casing of the indoor unit and part of the sealed container being omitted.

[0069] FIG. 3 shows an upper section of the indoor unit of FIG. 2, but with the sealed container arranged therein.

[0070] FIG. 4A shows the scaled container of FIG. 3 in isolation.

[0071] FIG. 4B shows the sealed container of FIG. 4A with the top, bottom and two side walls being omitted.

[0072] FIG. 5 shows another embodiment of the sealed container partly as explosive view.

[0073] FIG. 6 shows an alternative embodiment for the arrangement of the chimney in the indoor unit.

[0074] FIG. 7 shows another alternative embodiment of the indoor unit having a sealed container, which protrudes from the top of the outer casing of the indoor unit.

[0075] FIG. 8 shows an alternative arrangement of piping to and from the sealed container, passing through the release opening.

DESCRIPTION OF EMBODIMENTS

[0076] Subsequently, several embodiments of the heat pump of the present invention will be described in detail.

[0077] In general, a heat pump comprises a refrigerant circuit, which, in the present embodiments, is configured to circulate flammable refrigerant. Refrigerant used in the exemplary embodiments of the present invention consists of R32, as R32 enables efficient heat exchange while having a low GWP. Usually, R 32 comprises a higher density than air under atmospheric pressure. Thus, R32 usually concentrates at bottom sections of spaces or volumes. Issues stemming from the density of R32 and its flammability characterises will be described in more detailed below. Further, other flammable refrigerants can also be used in the context of the present invention.

[0078] The refrigerant circuit used in the heat pump of the present invention corresponds to a commonly known refrigerant circuit, which comprises at least a compressor, a utilization-side heat exchanger (e.g. for domestic hot water or space heating/cooling such as air conditioning or floor heating), an expansion device (e.g. main expansion valve) and a heat-source-side exchanger (e.g. outdoor air heat exchanger or ground source heat exchanger). All elements are connected by piping, such that refrigerant can flow from one component to the other and can achieve heat exchange with a second medium.

[0079] The subsequently described exemplary embodiments of the heat pump relate to an air heat pump, wherein the above-noted elements of the refrigerant circuit are separately housed in an outdoor unit and indoor unit.

[0080] The exemplary (not illustrated) outdoor unit accommodates at least the main expansion valve, the compressor and the heat-source-side heat exchanger, whereas the exemplary indoor unit 10, which will be described in more detail below, accommodates at least the utilization side heat exchanger 19. This provides for a quiet and compact design of the indoor unit 19. Nonetheless, other configurations and arrangements of the refrigerant circuit in the indoor unit 10 and the outdoor unit an also applicable.

[0081] An exemplary embodiment of such an indoor unit 10 of an air heat pump is illustrated in FIG. 1. FIG. 1 shows a floorstanding indoor unit 10 for producing hot water e.g. as domestic hot water and/or space heating, which can be placed on the ground of an indoor space, i.e. a room inside a building, in which hot water should be produced. Yet, a wall-mounted indoor unit may also be applicable. The produced hot water can, for example, be used for bathroom applications (shower, bathtub, etc.), in the kitchen or for underfloor heating systems in a household.

[0082] FIG. 2 illustrates the overall configuration of the floorstanding indoor unit 10 shown in FIG. 1, wherein the lateral part of the outer casing 15 thereof has been removed.

[0083] To start from the (not shown) ground of the indoor space, on which the indoor unit 10 is placed, an isolated tank 11 is provided on a base plate 12, wherein the lateral outer casing 15 of the indoor unit 10 (not shown in FIG. 2) can be mounted thereto.

[0084] The isolated tank 11 can be made of stainless steel and can be covered by an isolation material. The isolated tank 11 stores the domestic hot water generated by the indoor unit 10 and efficiently avoids a rapid cool down of the generated hot water. This enables that hot water is directly and permanently available at any time. In the exemplary embodiment of the floorstanding indoor unit 10 the isolated tank 11 may have a volume of 180 to 230 litres. Nonetheless, the present application is not limited thereto, and other volumes are also applicable.

[0085] A drain pan 13 is provided above said isolated tank 11 to allowed drainage of any condensation water accumulated on the drain pan. In the exemplary embodiment of FIGS. 1 and 2, all elements required for producing hot water inside the indoor unit 10 are provided above said drain pan 13 and will be described in more detail below.

[0086] Above that, the outer casing 15 of the indoor unit 10 comprises a top 16 that forms the top section of the outer casing 15 of the indoor unit 10.

[0087] Water connection pipes 14 protrude from said top 16 of the outer casing 15 to provide a top connection of the indoor unit 10 of the heat pump. That is, the water connection pipes 14, in the present embodiment, may be part of a closed loop and connect the indoor unit 10 to at least one heating application such as a floor heating, a radiator, an air heating or the like. Additionally, a coil immersed in a domestic hot water tank (isolated tank 11) may be part of said closed loop to heat water contained in the domestic hot water tank. Accordingly, the water connection pipes 14 enable to stream, e.g., relatively hot water out of the indoor unit 10 to its desired application inside the household, and to stream relatively cold water into the indoor unit 10. A domestic hot water pipe 26 and a freshwater pipe 27 are provided to respectively withdraw hot water from the domestic hot water tank and feed freshwater to the domestic hot water tank for refilling.

[0088] In the present embodiment, water in the closed loop flowing into the indoor unit 10 is guided through the utilization-side heat exchanger 19 of the indoor unit 10. Inside said utilization side heat exchanger 19, the water exchanges heat with the refrigerant of the refrigerant circuit, here R32, and, hence, is heated. Subsequently, the heated water is flown out of the utilization-side heat exchanger 19 and flown through a coil disposed in the isolated tank 11 so that water contained in the isolated tank 11 is heated. In addition (as in the present embodiment) or as an alternative the heated water may be directly flown to at least one heating application, such as a floor heating, radiator, an air heating or the like. If required a switching device can be provided so that the heated water may be circulated through the coil for producing domestic hot water or the at least one heating application for space heating depending on the demand. If hot water is required for a domestic application, such as a tap water, it may then be taken out of the isolated tank 11 and be flown via domestic hot water pipe 26 out of the indoor unit 10 to its domestic application, e.g. in the same or a different room of the house. For refilling the isolated tank 11, cold water is flown into the tank via a freshwater pipe 27. Certainly, the invention is not limited in this regard and other embodiments are conceivable.

[0089] To achieve the above-mentioned heat exchange between hot, gaseous R32 and cold water inside the utilization-side heat exchanger 19, hot, gaseous R32 is streamed from the (not shown) outdoor unit into the utilization side heat exchanger 19 via a gaseous refrigerant pipe 17.

[0090] Consequently, heat between the hot, gaseous refrigerant entering the utilization-side heat exchanger 19 via the gaseous refrigerant pipe 17 and the cold water can be exchanged in said utilization-side heat exchanger 19. Vice versa, not only the water is heated thereby, but the temperature of the refrigerant is reduced accordingly. Depending on the desired application, the heat exchange can be performed in both, a parallel flow or counter flow inside the utilization-side heat exchanger 19.

[0091] Due to the described cool down of the refrigerant during the heat exchange inside the utilization-side heat exchanger 19, the refrigerant gets liquidated, exits the utilization-side heat exchanger 19 via a liquid refrigerant pipe 18, and is then streamed out of the indoor unit 10 and back to the (not shown) outdoor unit of the refrigerant circuit. Therein, the temperature of the refrigerant is increased again due to a compression and a heat exchange inside the heat-source-side heat exchanger of the refrigerant circuit. The refrigerant can then be used for a further heat exchange with cold water inside the utilization-side heat exchanger 19 to produce, e.g., hot water.

[0092] Further commonly known elements of an air heat pump indoor unit, such as air purge valves, a magnetic filter, a controller, a three-way-valve, a flow sensor, an expansion vessel, a pressure sensor, a backup heater, a connection terminal, a switch box, a user interface, a circulation pump, etc. are not relevant for the description of the exemplary embodiments and are well known to a skilled person, such that a further description thereof will be omitted. Accordingly, some of the elements are also not illustrated in the drawings for orientation purposes.

[0093] FIG. 3 shows an upper part of the indoor unit 10 of the exemplary embodiment shown in FIGS. 1 and 2. It is adherent from FIG. 3 that the indoor unit 10 comprises a sealed container 20, which is accommodated inside the outer casing 15 of the indoor unit 10. Said sealed container 20 is an airtight container, which in the present embodiment comprises a bottom 21 and a top 22 and can accommodate at least one of the compressor, the utilization-side heat exchanger 19, the expansion device, and the heat-source-side heat exchanger. Even though the present embodiment shows the sealed container as being configured as a sheet metal box, other configurations are as well conceivable.

[0094] One such example is shown in FIG. 5. In this example, the sealed container 20 may be made of at least two members of different material. The two members may comprise a shell 29 made of e.g. plastic material and a lid 30 made of e.g. sheet metal. The shell 29 substitutes for example four of the sheet metals of the embodiment shown in FIG. 4, for example those resembling the bottom 21, the top 22 and three of the side walls 28. One remaining side wall 28, particularly that through which the pipes 14, 17, 18 pass and comprising the sealed contact areas 25, is maintained as lid 30 of sheet metal. As compared to a sheet metal box, wherein sealings are required between each and every sheet metal, this embodiment merely requires one sealing 31 between the shell 29 and the lid 30. The chimney 24, in this embodiment, is shown relatively short so that the release opening 23 is situated only slightly above the top 22. Yet, in other embodiments, the chimney 24 may be extended by a tube or pipe so as to provide the release opening 23 at a higher position similar as shown in the embodiment in FIG. 3.

[0095] In the exemplary embodiments described herein, the sealed container 20 exemplarily accommodates and completely covers the utilization side heat exchanger 19. It is highlighted in this regard, that the sealed container is not shown in FIG. 2 except for the side walls 28 through which the gaseous refrigerant pipe 17, the liquid refrigerant pipe 18 and the water connection pipes 14 pass. Additionally, the scaled container 20 is shown in isolation in FIG. 4A and in order to show its interior with the bottom 21, the top 22 and two of the side walls 28 being removed in FIG. 4B.

[0096] Nonetheless, it is also possible that at least one or all of the compressor, the expansion valve and the heat-source-side heat exchanger are also accommodated in the sealed container. In such a configuration the sealed container 20 can then be the outer casing of the indoor unit 10.

[0097] Providing a scaled container 20 that completely covers and accommodates the utilization side heat exchanger 19 of the indoor unit 10 enables to avoid issues related to potentially leaking refrigerant inside the utilization side heat exchanger 19. Said configuration may avoid an uncontrolled exhaust of flammable refrigerant, here R32, into the indoor space, in which the indoor unit 10 is arranged. Water and refrigerant piping entering or leaving the sealed container 20 for connecting the utilization-side heat exchanger 19 with the refrigerant circuit and the above-described water circuit penetrate through the walls of the sealed container in the embodiment of FIGS. 1 to 3. Yet, said penetration areas are also sealed, such that an uncontrolled exhaust of leaking refrigerant can be also avoided at said sealed contact areas 25 of the sealed container 20.

[0098] To avoid that the pressure inside said sealed container 20 rises due to leaking refrigerant and to prohibit an uncontrol exhaust of the leaked flammable refrigerant into the indoor space, the sealed container 20 comprises a release opening 23. Said release opening 23 enables that leaking refrigerant can be exhausted to the exterior of the outer casing 15 of the indoor unit 10 in a more controlled manner. This enables that a sufficient dispersion of exhausted flammable refrigerant can be achieved and the risk of flammable refrigerant concentration in the indoor space can be prohibited.

[0099] It becomes apparent from a comparison of FIGS. 2, 3 and 4A, 4B that also the connection of the utilization side heat exchanger 19 to the piping of the refrigerant circuit is arranged inside the sealed container 20 and only the piping of the refrigerant circuit and the water connecting pipes enter/exit the sealed container 20. Thus, the potential leaking points, namely the utilization side heat exchanger 19, such as a plate heat exchanger, and the connection of the utilization side heat exchanger 19 to the piping of the refrigerant circuit are arranged in the sealed container 20. To put it differently, brazing connections at which leakage likely occurs are disposed within the sealed container 20. Accordingly, risks stemming from leaking refrigerant at said connection points of the utilization side exchanger 19 to the remaining part of the refrigerant circuit can be reduced, as said leaking refrigerant would merely leak into the sealed container and could then be exhausted to the exterior of the outer casing 15 of the indoor unit 10 via the release opening 23 in a more controlled manner.

[0100] To achieve such a controlled release of leaking refrigerant via the release opening 23, the leaked refrigerant must be exhausted sufficiently high. In the embodiment shown in FIG. 3, the sealed container 20 comprises a chimney 24 having a rust end and a second end. The first end of the chimney 24 is in fluid communication with an interior of the sealed container 20, in which the utilization-side heat exchanger 19 is arranged. Vice versa, the release opening 23 of the sealed container 20 is arranged at the second end of the chimney. This chimney 24 aims to increase the release height of leaking refrigerant. This provides a sufficient dispersion of the leaked refrigerant inside the indoor space, while keeping the overall size of the indoor unit 10 small.

[0101] In the exemplary embodiment of FIGS. 1 to 3, the chimney 24 represents a straight pipe, wherein the first end is a lower end of the chimney and the second end is a at a higher position than the first end.

[0102] Further, the chimney 24 of the embodiment of FIGS. 1 to 3, and accordingly also the release opening 23 of the sealed container 20, protrudes through the top 16 of the outer casing 15 of the indoor unit 10 in a height direction to exhaust leaking refrigerant to the exterior of the outer casing 15 as high as possible.

[0103] Exhausting leaking flammable refrigerant as high as possible ensures that a sufficient dilution of leaking R32 can be achieved and flammable refrigerant concentration inside the indoor space can be avoided. Specific requirements for the height of the release opening are exemplified in more detail below.

[0104] In further, not illustrated embodiments, it is also possible that the chimney 24 extends in a horizontal direction, such that the first end and the second end of the chimney 24 are arranged at the same (height) level.

[0105] It is also possible that the chimney 24 protrudes from a side surface of the sealed container 20. Said side surface represents a vertical surface of the sealed container that is arranged between the bottom 21 and the top 22 of the sealed container 20.

[0106] In this context, the chimney 24 may comprise a “L”-shape, such that a second end thereof opens in a direction facing away from the base plate 11 of the indoor unit 10 and is arranged at a higher position than the first end of the chimney 24 being in fluid communication with the inside of the sealed container 20. Such a configuration is exemplarily shown in the embodiment of FIG. 6.

[0107] FIG. 6 represents a facilitated cross-sectional view of the upper section of a similar indoor unit 10 than the one described with respect to FIGS. 1 to 4B. FIG. 6 merely differs in the shape and arrangement of the chimney 24. Accordingly, the redundant description of similar elements than in the embodiment of FIGS. 1 to 4B is omitted. Further, it is highlighted that the connection of the gaseous refrigerant pipe 17 and the water connection pipe 14 at the upper section of the sealed container 20 are omitted in FIG. 6 for orientation purposes as well.

[0108] Nonetheless, it is, with respect to the embodiment of FIG. 6, adherent that also the release opening 23 of the “L”-shaped chimney 24 at the second end of the chimney 24 of FIG. 6 is positioned at a height H above the ground of the indoor space as explained above. In one particular embodiment, the release opening 23 of the chimney 24 of FIG. 6 is positioned above the top 16 of the outer casing 15. In either case, leaking refrigerant inside the sealed container 20 can be exhausted at a sufficiently high position in this embodiment. Such an arrangement provides a simple, secure and flexible arrangement of the utilization-side heat exchanger 19 inside the indoor unit 10. In an other embodiment, depicted by the dashed lines in FIG. 6, the chimney 24 may be directed downwards, i.e. the release opening 23 is facing the floor. Thus, the risk of foreign matter entering the sealed container 20 via the chimney 24 is reduced. In the shown embodiment, the release opening 23 is disposed lower than the bottom 21 of the sealed container 20. Yet, care must be taken that the height of e release opening 23 still fulfills the above-described requirements.

[0109] A further, alternative indoor unit embodiment is shown in the cross-sectional view of FIG. 7. Said embodiments differs from the embodiments described above in the configuration of the sealed container 20 and the release opening 23 and does not require a chimney. Nonetheless, the description of similar elements than the ones of the previously described embodiments will be omitted.

[0110] The release opening 23 of the embodiment of FIG. 7 is arranged in the top 22 of the scaled container 20. Further, the scaled container 20 protrudes through the top 16 of the outer casing 15 of the indoor unit 10.

[0111] Accordingly, the provision of a chimney can be omitted and a simple configuration for releasing potentially leaking flammable refrigerant at the highest possible position of the indoor unit can be achieved.

[0112] In a further, not shown embodiment, it is possible that the release opening 23 of the embodiment of FIG. 7 extends over the whole diameter of the top of the sealed container 20. In other words, the sealed container 20 is fully opened at its top 22, such that dispersion of leaking flammable refrigerant in the utilization-side heat exchanger 19 can be achieved by an exhaust at the highest possible position. Further, this facilitates the arrangement of the utilization-side heat exchanger 19 inside the sealed container 20.

[0113] A further embodiment is shown in the cross-sectional view on part of the indoor unit 10 of FIG. 8. In this embodiment, the utilisation-side heat exchanger 19, which is accommodated in the sealed container 20 and all corresponding water and refrigerant pipings, such as the gaseous refrigerant pipe 17, the liquid refrigerant pipe 18 as well as the water connecting pipes 14, enter and leave the scaled container 20 through the release opening 23.

[0114] An arrangement of the pipings entering and exiting the scaled container 20 through the release opening 23 enable to avoid scaled contact areas 25, e.g. in the side walls of the sealed container 20, through which leaked refrigerant could potentially be exhausted from the sealed container 20 in an uncontrolled manner. Accordingly, the safety of such an indoor unit 10 can be improved.

[0115] Please note that such an arrangement works with all of the above described embodiments, namely the ones having a chimney 24 and the ones having a release opening 23 in the top 22 of the sealed container 20 that protrudes from the top 16 of the indoor unit 10.

[0116] Irrespective of the actual configuration and arrangement of the sealed container 20, the chimney 24, the release opening 23 or the like, it once again highlighted that it is important to situate the release opening 23 of the sealed container 20 as high as possible above a ground of the indoor space, when the outer casing of the indoor unit is installed therein.

[0117] This enables that, if flammable refrigerant is leaking out of the utilization-side heat exchanger 19 or at its connection points to the remaining elements of the refrigerant circuit arranged in the outdoor unit, it can primarily be gathered inside the sealed container 20. Should the amount of leaking refrigerant increase and fill the sealed container, the leaking refrigerant can then be exhausted to the exterior of the indoor unit 10 and into the indoor space at a high position via the release opening 23.

[0118] As the flammable refrigerant used in the above-described embodiments has a higher density than air under atmospheric pressure, the flammable refrigerant will gather at a bottom section of the indoor space. This may provoke a dangerous concentration of flammable refrigerant inside the indoor space, which may, in a worst-case scenario, lead to an inflammation.

[0119] Accordingly, all embodiments described above aim to, primarily, -position all potential refrigerant leakage points inside the sealed container. Thus, the height where refrigerant is released from the sealed container can reliably be determined/defined and adjusted to the needs, in particular by appropriately arranging the release opening. Particularly, the refrigerant can be released so as to guarantee sufficient dilution of the refrigerant in the indoor space. This reduces the risk of a flammable refrigerant concentration inside the indoor space.

[0120] Having a release opening 23 at an end of a chimney 24 or at a top 22 of sealed container 21 that protrudes from the top of the indoor unit, enables to achieve said dispersion due to the sufficient height of the release opening, respectively.

[0121] In this light, all described embodiments relate to enhanced tightness refrigerating systems and exhaust the flammable refrigerant via the release opening 23 at least 1.8 m above the ground of the indoor space, in which the indoor unit is situated. The height H of the release opening has been highlighted in FIG. 2 for orientation purposes. Accordingly, no ventilation or the like is required—also in small indoor space (such as domestic households) having an overall area of the indoor space of 200 m.sup.2 or less.

[0122] Nonetheless, arrangements with a lower release height via the release opening 23 are also applicable. In this context, it is possible to arrange the release height of leaked flammable refrigerant via the release opening 23 below 1.8 m relative the ground of the indoor space in which the indoor unit is arrangement. Yet, said configurations may require additional means to guarantee safe handling in the case of leakage. An example of such additional means is a fan increasing the mixing of the leaked refrigerant with the available air volume in the indoor space or even exchanging the air in the indoor space by use of actively venting the indoor space. The fan may be operated continuously or starting the fan may be triggered by detecting a refrigerant leak. Thus, sufficient dispersion of the leaked flammable refrigerant in the interspace may be achieved. Other examples which may be embodied comprise alarm functions or evacuation of the refrigerant present in the refrigerant circuit to a location within the refrigerant circuit where it can safely be stored, such as an outdoor unit of the heat pump.

[0123] For non-enhanced tightness refrigerating systems, the height of the release opening 23 must be equal to or higher than the higher result of the following formulas:

[00003]$H\ge \frac{mc}{2.5\star {\mathrm{LFL}}^{\frac{5}{4}}\star A^{\frac{1}{2}}}\mathrm{OR}H\ge \frac{mc}{\mathrm{SF}\star \mathrm{LFL}\star A}$

[0124] H reflects the minimum height of the release opening 23 measured from a ground of the indoor space, me reflects a mass of the refrigerant in the refrigerant circuit, LFL reflects a lower flammability limit of the used refrigerant, SF reflects a safety factor, and A represents the area of the indoor space. The lower flammability limit of R32 can exemplarily be considered as LFL=0.307, the safety factor as SF=0.75 and the area of the indoor space as A=200 m.sup.2.

[0125] Inserting the above-mentioned values of SF=0.75 and A=200 m.sup.2 in the formulas above provides the following formulas:

[00004]$H\ge \frac{mc}{35\star {\mathrm{LFL}}^{\frac{5}{4}}}\mathrm{OR}H\ge \frac{mc}{150\star \mathrm{LFL}}$

[0126] Yet, other values for the area of the indoor space A, the safety factor SF, etc. are also applicable. Said height H of the release opening has been highlighted in FIG. 2 for orientation purposes.

[0127] In case of installing an indoor unit in the form of a floorstanding indoor unit, the height can be measured from the ground or floor of the indoor space, which is in direct contact with a base plate or stand of the indoor unit. Yet, different installations of the indoor unit, for example on a shelf or a platform, are also applicable. In such cases, the release opening height is not calculated from the platform being in contact with the indoor unit, but from the ground of the indoor space, which is in contact with the platform. Even when several elements are arranged between the indoor unit (comprising the release opening) and the ground of the indoor space, the release opening height is calculated from the ground of the indoor space to the release opening of the sealed container—irrespective of the number of elements arranged in between. In any case, for non-enhanced tightness refrigerating systems, the minimum height of the release opening above the ground (floor) of the indoor space should be 0.6 m.

REFERENCE SIGNS LIST

[0128] 10 indoor unit [0129] 11 isolated tank [0130] 12 base plate [0131] 13 drain pan [0132] 14 water connection pipe [0133] 15 outer casing [0134] 16 top of the outer casing [0135] 17 gaseous refrigerant pipe [0136] 18 liquid refrigerant pipe [0137] 19 utilization-side heat exchanger [0138] 20 sealed container [0139] 21 bottom of the sealed container [0140] 22 top of the sealed container [0141] 23 release opening [0142] 24 chimney [0143] 25 sealed contact area [0144] 26 domestic hot water pipe [0145] 27 freshwater pipe [0146] 28 side walls of the sealed container [0147] 29 shell [0148] 30 lid [0149] 31 scaling

CITATION LIST

Patent Literature

[0150] [PATENT LITERATURE 1] EP 3222941 A1

[0151] [PATENT LITERATURE 2] FR 2827948 B1

[0152] [PATENT LITERATURE 3] EP 3139105 A1