LOCAL HEATING INSTALLATION AND HEATING SYSTEM COMPRISING SUCH A LOCAL HEATING INSTALLATION

Abstract

 A local heating installation for providing comfort heating and tap hot-water in a building, comprising:
- a heating circuit (11) containing heating liquid;
- a first heat exchanger (18) for preheating tap hot-water by means of heat from the heating liquid;
- a second heat exchanger (19) for final heating of tap hot-water by means of heat from the heating liquid;
- a local heat pump (30); and
- an electronic control device (40), which in dependence on the temperature of the heating liquid in a feed conduit (13) of the heating circuit is configured to either:
• keep said heat pump out of operation and direct heating liquid from said feed conduit to the second heat exchanger (19) for final heating of the preheated tap hot-water, or
• prevent a flow of heating liquid from said feed conduit to the second heat exchanger (19) and direct heating liquid to an input side (30a) of said heat pump for generation of heat for final heating of the pre-heated tap hot-water.

Description

FIELD OF THE INVENTION AND PRIOR ART

[0001] The present invention relates to a local heating installation according to the preamble of claim 1 for providing comfort heating and tap hot-water in a building. The invention also relates to a heating system comprising a central heat production plant and one or more such local heating installations.

[0002] Heating systems with a central heat production plant and several local heating installations for providing comfort heating and tap hot-water in a respective building or part of a building are previously known in various configurations. In such a heating system, the local heating installations are connected to the central heat production plant through a distribution grid, wherein each local heating installation is configured to provide comfort heating and tap hot-water in the associated building by utilizing heat energy produced by one or more heat energy producing devices included in the central heat production plant. Heating systems of this type are previously known from EP 2 438 358 B1 and EP 3 833 907 B1.

[0003] In order to reduce the risk for Legionnaires' disease, tap hot-water is to be heated to a temperature of at least 50 °C. Legionnaires' disease is caused by Legionella bacteria and is a serious type of pneumonia. Legionella bacteria live and grow in water systems at temperatures of 20 to 50 °C. The Legionella bacteria will slowly die at temperatures in the range of approximately 50-55 °C, and will rather rapidly die at temperatures above 55 °C.

[0004] In the heating systems disclosed in EP 2 438 358 B1 and EP 3 833 907 B1, each local heating installation is provided with a local heat pump for final-heating of tap hot-water. Hereby, the local heating installations may be supplied with heating liquid having a temperature below 50 °C, for instance in the range of 30-40 °C, while still allowing a required heating of the tap hot-water to a temperature of 50 °C or higher by means of the local heat pump. Without such local heat pumps, it would be necessary to supply each local heating installation with heating liquid having a temperature in the range of 60 °C or higher in order to be able to achieve the required temperature of the tap hot-water. Thus, the use of local heat pumps for heating of tap hot-water in the local heating installations makes it possible to reduce the required temperature of the heating liquid supplied to the local heating installations, which in its turn implies reduced heat losses in the heating system.

OBJECT OF THE INVENTION

[0005] The object of the present invention is to provide a local heating installation of the above-mentioned type that has a new and favourable design.

SUMMARY OF THE INVENTION

[0006] According to the invention, said object is achieved my means of a local heating installation having the features defined in claim 1.

[0007] The local heating installation according to the invention is to be used for providing comfort heating and tap hot-water in a building and comprises:

• a heating circuit containing heating liquid, wherein the heating circuit comprises a feed conduit for supply of heating liquid heated under the effect of heat energy produced by one or more heat energy producing devices of a central heat production plant and a return conduit for the heating liquid;
• a heat emitting assembly configured to provide comfort heating by heating air within said building while utilizing heat energy derived from the heating liquid of the heating circuit, wherein the heat emitting assembly is connected to said feed conduit in order to allow supply of heating liquid to the heat emitting assembly via the feed conduit and connected to said return conduit in order to allow return of heating liquid from the heat emitting assembly via the return conduit;

• a first heat exchanger, which has a first side connected to the heating circuit and a second side connected to a water supply line and which is configured to preheat tap hot-water by transferring heat from the heating liquid in the heating circuit to water in the water supply line;
• a local heat pump, which has an input side connected to the feed conduit or the return conduit of the heating circuit and which is capable of generating heat for final heating of the preheated tap hot-water by absorbing heat energy from the heating liquid in the heating circuit;
• flow regulating devices, in the form of one or more control valves and/or one or more circulation pumps, for controlling flow paths of the heating liquid in the heating circuit;
• an electronic control device for controlling the local heat pump and said flow regulating devices,
• a second heat exchanger for final heating of tap hot-water preheated by the first heat exchanger, wherein a first side of the second heat exchanger is connectable to said feed conduit in order to allow the first side of the second heat exchanger to receive a flow of heating liquid from the feed conduit and wherein a second side of the second heat exchanger is connected or connectable to the second side of the first heat exchanger in order to allow the second side of the second heat exchanger to receive preheated tap hot-water from the first heat exchanger; and
• at least one temperature sensor configured to measure a temperature that reflects the temperature of the heating liquid in said feed conduit, wherein the electronic control device is configured to receive measuring values from said at least one temperature sensor.

[0008] When it is established by the electronic control device that the temperature of the heating liquid in said feed conduit is higher than a predetermined threshold temperature, the electronic control device is configured to keep the local heat pump out of operation and control said flow regulating devices to direct a flow of heating liquid from said feed conduit to the first side of the second heat exchanger to thereby allow the second heat exchanger to effect final heating of the preheated tap hot-water by transferring heat from the heating liquid in this flow of heating liquid to the preheated tap hot-water. In the following, this operating situation, i.e. when the temperature of the heating liquid in the feed conduit is higher than the threshold temperature, is referred to as the first operating situation.

[0009] When it is established by the electronic control device that the temperature of the heating liquid in said feed conduit is lower than said threshold temperature, the electronic control device is configured to control said flow regulating devices to prevent a flow of heating liquid from said feed conduit to the first side of the second heat exchanger and to direct a flow of heating liquid from said feed conduit or said return conduit to the input side of the local heat pump to thereby allow the local heat pump to generate heat for final heating of the pre-heated tap hot-water by absorbing heat energy from the heating liquid in this flow of heating liquid. In the following, this operating situation, i.e. when the temperature of the heating liquid in the feed conduit is lower than the threshold temperature, is referred to as the second operating situation.

[0010] The threshold temperature is to be so adapted that the second heat exchanger will be capable of heating the tap hot-water to the required final temperature, normally a temperature of at least 50 °C, when the temperature of the incoming heating liquid of the heating circuit is higher than the threshold temperature. Thus, the threshold temperature should be slightly higher, normally at least 2 °C higher, than the required final temperature of the tap hot-water.

[0011] When the heating demand of the heat emitting assembly is low, i.e. when the outside temperature is high and there is a low demand for comfort heating, or alternatively no demand at all for comfort heating, the temperature of the incoming heating liquid of the heating circuit may be kept at a low level and the local heat pump may be operated in order to effect the required final heating of the tap hot-water, which implies that the heat losses in the heating system may be reduced. When the heating demand of the heat emitting assembly is high, i.e. when the outside temperature is low and there is a high demand for comfort heating, supply of heating liquid to the heat emitting assembly with a temperature higher than the threshold temperature might be required in order to achieve the required comfort heating, wherein a part of this hot incoming heating liquid may be directed directly to the second heat exchanger and used in this heat exchanger for the required final heating of the tap hot-water, which implies that the final heating of tap hot-water may be achieved in an energy efficient manner.

[0012] When the outside temperature is low and there is a high demand for comfort heating, electricity is sometimes in short supply and available only at high prices. Under these circumstances, the required tap hot-water may, with the local heating installation according to the invention, be produced in a cost-efficient manner by heat exchange with the heating liquid in the heating circuit without requiring any operation of the electricity-consuming local heat pump.

[0013] The above-mentioned threshold temperature is with advantage in the range of 52-65 °C, preferably 52-60 °C, and more preferably 52-55 °C

[0014] According to an embodiment of the invention, the first side of the second heat exchanger is connectable to an output side the local heat pump, wherein the electronic control device is configured to control said flow regulating devices to direct a flow of heating liquid from the output side of the local heat pump to the first side of the second heat exchanger in said second operating situation to thereby allow the second heat exchanger to effect final heating of the preheated tap hot-water in the second operating situation by transferring heat from the heating liquid in this flow of heating liquid to the preheated tap hot-water. In this case, the second heat exchanger is used for final heating of the tap hot-water also in said second operating situation, wherein the first side of the second heat exchanger is supplied with a flow of heating liquid directly from the feed conduit of the heating circuit in the first operating situation and with a flow of heating liquid from the local heat pump in the second operating situation. In this case, heating liquid may be circulated in a loop between a condenser of the local heat pump and the first side of the second heat exchanger in the second operating situation.

[0015] Another embodiment of the invention is characterized in:

• that the local heating installation comprises a tap hot-water circuit, in which the final-heated tap hot-water is circulated, and a circulation pump arranged in the tap hot-water circuit for circulating the final-heated tap hot-water therein;
• that the second side of the second heat exchanger is connected to the tap hot-water circuit in order to allow the tap hot-water circuit to receive tap hot-water that has been subjected to final heating by the second heat exchanger in said first operating situation; and
• that the local heat pump has an output side connected to the tap hot-water circuit in order to allow transfer of heat from a working medium of the local heat pump to tap hot-water in the tap hot-water circuit in a condenser of the local heat pump for final-heating of the tap hot-water in said second operating situation.

[0016] In this case, the second heat exchanger is used for final heating of the tap hot-water only in the first operating situation, wherein the tap hot-water is final heated directly in the local heat pump in the second operating situation.

[0017] According to another embodiment of the invention, the first side of the second heat exchanger is connected to the heating circuit in series with the first side of the first heat exchanger to thereby allow heating liquid that has passed through the first side of the second heat exchanger in said first operating situation to be directed into the first side of the first heat exchanger for use in the preheating of the tap hot-water.

[0018] The input side of the local heat pump is preferably connected to the return conduit of the heating circuit in order to receive a flow of heating liquid from the return conduit in said second operating situation, wherein an inlet of an evaporator of the local heat pump is connected to the return conduit via a connecting conduit included in the heating circuit, and an outlet of said evaporator is connected to the return conduit via another connecting conduit included in the heating circuit. Thus, in this case, the input side of the local heat pump is connected to the heating circuit downstream of the heat emitting assembly, which is favourable with respect to the heating capacity of the heat emitting assembly in said second operating situation.

[0019] Other favourable features of the local heating installation according to the invention will appear from the dependent claims and the description following below.

[0020] The invention also relates to a heating system comprising:

• a central heat production plant with one or more heat energy producing devices; and
• one or more local heating installations of the above-mentioned type for providing comfort heating and tap hot-water in a respective building or part of a building by utilizing heat energy produced by said heat energy producing devices.

[0021] Other favourable features of the heating system according to the invention will appear from the dependent claims and the description following below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The invention will in the following be more closely described by means of embodiment examples, with reference to the appended drawings. It is shown in:

Fig 1

a schematic illustration of a heating system according to an embodiment of the present invention,

Figs 2a and 2b

schematic illustrations of a local heating installation according to a first embodiment of the invention,

Fig 3

a schematic illustration of a local heating installation according to a second embodiment of the invention,

Fig 4

a schematic illustration of a local heating installation according to a third embodiment of the invention, and

Figs 5a and 5b

schematic illustrations of a local heating installation according to a fourth embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0023] A heating system 1 according an embodiment of the invention is schematically illustrated in Fig 1. The heating system 1 comprises a central heat production plant 2 with one or more heat energy producing devices 3a, 3b. In the illustrated embodiment, the central heat production plant 2 comprises a first heat energy producing device 3a in the form of a central heat pump and a second heat energy producing device 3b in the form of a heating boiler. However, the central heat production plant 2 may comprise any other suitable number of heat energy producing devices 3a, 3b and any other suitable types of heat energy producing devices 3a, 3b.

[0024] The heating system 1 also comprises one or more local heating installations 10 for providing comfort heating and tap hot-water in a respective building or part of a building by utilizing heat energy produced by the heat energy producing devices 3a, 3b of the central heat production plant 2. These local heating installations 10 will be described in closer detail below with reference to Figs 2-5. Heating liquid heated under the effect of heat energy produced by the heat energy producing devices 3a, 3b is supplied to the local heating installations 10 through a distribution grid 5 included in the heating system 1. The local heating installations 10 are preferably connected to the distribution grid 5 in parallel with each other, wherein an inlet 10a of each local heating installation 10 is connected to a feed conduit 5a of the distribution grid 5 and an outlet 10b of each local heating installation 10 is connected to a return conduit 5b of the distribution grid 5. Each local heating installation 10 is configured to receive heating liquid at a first temperature level from the feed conduit 5a via the inlet 10a of the local heating installation 10 and to discharge the heating liquid at a lower second temperature level to the return conduit 5b via the outlet 10b of the local heating installation 10 when the heating liquid has passed through a heating circuit 11 (see Figs 2-5) of the local heating installation 10.

[0025] A circulation pump 5c is arranged in the distribution grid 5 in order to circulate heating liquid between the central heat production plant 2 and the local heating installations 10 via the feed conduit 5a and return conduit 5b of the distribution grid 5.

[0026] In the illustrated embodiment, the heating system 1 comprises three local heating installations 10. However, the heating system 1 of the present invention may comprise only one local heating installation 10 or two local heating installations 10 or any other suitable number of local heating installations 10.

[0027] In the illustrated embodiment, the central heat production plant 2 comprises a circulation circuit 6, which contains a liquid medium, such as for instance water. A circulation pump 7 is arranged in the circulation circuit 6 for circulating the medium in the circulation circuit. The circulation circuit 6 is connected to a heat source 8, which is configured to emit heat to the medium in the circulation circuit 6. In the illustrated embodiment, the heat source 8 has the form of a thermal energy store, which is connected to the circulation circuit 6 in order to allow heat exchange between the thermal energy store and the medium in the circulation circuit 6. The thermal energy store is with advantage a vertical or horizontal ground heat exchanger. A ground heat exchanger comprises collector pipes 9 installed in the ground. In the illustrated embodiment, the medium in the circulation circuit 6 is circulated through the collector pipes 9 of the thermal energy store in order to absorb heat from the ground. In a vertical ground heat exchanger, the collector pipes 9 are installed in vertical or inclined boreholes in the ground. In a horizontal ground heat exchanger, the collector pipes 9 are installed horizontally at a suitable depth in the ground. However, any other suitable type of heat source may also be used. The central heat pump 3a has an input side 4a connected to the circulation circuit 6 and an output side 4b connected to the feed conduit 5a of the distribution grid 5. The central heat pump 3a is configured to heat the heating liquid in the distribution grid 5 by absorbing heat energy from the medium in the circulation circuit 6. The heating liquid in the distribution grid 5 by also be heated by the heating boiler 3b, which is connected to the distribution grid 5 in parallel with the central heat pump 3a.

[0028] Different embodiments of a local heating installation 10 according to the invention are schematically illustrated in Figs 2-5. The local heating installation 10 is configured to provide comfort heating and tap hot-water in a house or other building.

[0029] The local heating installation 10 according to the invention comprises a heating circuit 11 containing heating liquid, such as for instance water or any other suitable type of liquid. In the illustrated embodiments, a circulation pump 12 is arranged in the heating circuit 11 for circulating the heating liquid in the heating circuit. However, the circulation of heating liquid in the heating circuit 11 may as an alternative be achieved by means of a circulation pump arranged in the above-mentioned distribution grid 5. The heating circuit 11 comprises a feed conduit 13 for supply of heating liquid heated under the effect of heat energy produced by the heat energy producing devices 3a, 3b of the central heat production plant 2 and a return conduit 14 for the heating liquid. Thus, when the local heating installation 10 is included in a heating system 1 of the type illustrated in Fig 1, the feed conduit 13 of the heating circuit 11 is connected to the feed conduit 5a of the distribution grid 5 in order to receive heating liquid from this feed conduit 5a and the return conduit 14 of the heating circuit 11 is connected to the return conduit 5b of the distribution grid 5 in order to discharge the heating liquid to this return conduit 5b after circulation through the heating circuit 11. In the illustrated embodiments, the circulation pump 12 is arranged in the feed conduit 13, but it could as an alternative be arranged in the return conduit 14.

[0030] The local heating installation 10 comprises a heat emitting assembly 15, which is configured to provide comfort heating by heating air within the building while utilizing heat energy derived from the heating liquid of the heating circuit 11. An inlet 15a of the heat emitting assembly 15 is connected to the feed conduit 13 of the heating circuit 11 in order to allow supply of heating liquid to the heat emitting assembly 15 via this feed conduit 13. An outlet 15b of the heat emitting assembly 15 is connected to the return conduit 14 of the heating circuit 11 in order to allow return of heating liquid from the heat emitting assembly 15 to the distribution grid 5 via this return conduit 14. The heat emitting assembly 15 comprises one or more heat emitting devices 16 configured to transfer heat from the heating liquid to air within the building. The heat emitting devices 16 may for instance have the form of conventional radiators. However, any other suitable types of heat emitting devices 16 capable of transferring heat from a circulating heating liquid to air within a building may also be used.

[0031] The local heating installation 10 further comprises a first heat exchanger 18 and a second heat exchanger 19 for heating of tap hot-water. The first heat exchanger 18 has a first side 18a connected to the heating circuit 11 and a second side 18b connected to a water supply line 20, wherein the first heat exchanger 18 is configured to preheat tap hot-water by transferring heat from the heating liquid in the heating circuit 11 to cold water in the water supply line 20. The second heat exchanger 19 is used for final heating of tap hot-water preheated by the first heat exchanger 18. The second heat exchanger 19 has a first side 19a that is connectable to the feed conduit 13 of the heating circuit 11 in order to allow the first side 19a of the second heat exchanger to receive a flow of heating liquid from this feed conduit 13. The second heat exchanger 19 has a second side 19b that is connected or connectable to the second side 18b of the first heat exchanger 18 in order to allow the second side 19b of the second heat exchanger 19 to receive water that has been preheated by the first heat exchanger 18.

[0032] The local heating installation 10 also comprises a local heat pump 30, which has an input side 30a connected to the heating circuit 11 and which is capable of generating heat for final heating of the preheated tap hot-water by absorbing heat energy from the heating liquid in the heating circuit 11. The local heat pump 30 also has an output side 30b, through which the local heat pump 30 is configured to emit heat for final heating of the preheated tap hot-water. The local heat pump 30 comprises a working medium circuit 31 with an evaporator 32, a condenser 33, a compressor 34 and an expansion valve 35, preferably an electromechanical expansion valve. The evaporator 32 is connected to the heating circuit 11 via an inlet 32a and an outlet 32b of the evaporator in order to allow heat exchange between heating liquid in the heating circuit 11 and the working medium of the heat pump, i.e. the medium in the working medium circuit 31, via the evaporator 32. By heat exchange with heating liquid in the heating circuit 11, the working medium of the local heat pump 30 absorbs heat energy via the evaporator 32. Work is added via the compressor 34, whereby the pressure and the temperature of the working medium is increased. In the condenser 33, heat energy is then, by heat exchange, emitted to another medium and the working medium of the local heat pump is then returned to the evaporator 32 via the expansion valve 35, the pressure and the temperature of the working medium being lowered when passing the expansion valve. The local heat pump 30 is a so-called liquid-to-liquid heat pump, which implies that it is configured to transfer heat energy from a liquid medium in the heating circuit 11 on the input side 30a of the local heat pump to a liquid medium on the output side 30b of the local heat pump.

[0033] Different flow paths for the heating liquid in the heating circuit 11 are controlled by flow regulating devices in the form of control valves 41, 42 and circulation pumps 43-46. The local heating installation 10 comprises an electronic control device 40 for controlling these flow regulating devices 41-46 and the local heat pump 30. The local heating installation 10 comprises at least one temperature sensor 48 configured to measure a temperature that reflects the temperature T1 of the heating liquid in the feed conduit 13 of the heating circuit 11, wherein the electronic control device 40 is configured to receive measuring values from this temperature sensor 48. The electronic control device 40 is configured to establish the prevailing temperature T1 of the heating liquid in the feed conduit 13 based on the measuring values from the temperature sensor 48 and compare this temperature T1 with a predetermined threshold temperature T_th, which preferably is in the range of 52-65 °C.

[0034] In a first operating situation, when it is established by the electronic control device 40 that the prevailing temperature T1 of the heating liquid in the feed conduit 13 is higher than the threshold temperature T_th, the electronic control device 40 is configured to keep the local heat pump 30 out of operation and control said flow regulating devices 41-45 to direct a flow of heating liquid from the feed conduit 13 to the first side 19a of the second heat exchanger 19 to thereby allow the second heat exchanger 19 to effect final heating of the preheated tap hot-water by transferring heat from the heating liquid in this flow of heating liquid to the preheated tap hot-water.

[0035] In a second operating situation, when it is established by the electronic control device 40 that the prevailing temperature T1 of the heating liquid in the feed conduit 13 is lower than the threshold temperature T_th, the electronic control device 40 is configured to control said flow regulating devices 41-45 to prevent a flow of heating liquid from the feed conduit 13 to the first side 19a of the second heat exchanger 19 and to direct a flow of heating liquid from the feed conduit 13 or return conduit 14 to the input side 30a of the local heat pump 30 to thereby allow the local heat pump 30 to generate heat for final heating of the pre-heated tap hot-water by absorbing heat energy from the heating liquid in this flow of heating liquid.

[0036] The electronic control device 40 may either be configured to change from the control mode of the second operating situation to the control mode of the first operating situation at the moment when it is established by the electronic control device 40 that the prevailing temperature T1 of the heating liquid in the feed conduit 13 has reached the threshold temperature T_th, or configured to change from the control mode of the second operating situation to the control mode of the first operating situation at the moment when it is established by the electronic control device 40 that the prevailing temperature T1 of the heating liquid in the feed conduit 13 exceeds the threshold temperature T_th.

[0037] In the embodiments illustrated in Figs 2-4, the first side 19a of the second heat exchanger 19 is connectable to the output side 30b the local heat pump 30. In this case, an output 33b of the condenser 33 of the local heat pump 30 is connected to an inlet 19c of the first side 19a of the second heat exchanger 19 via a first connecting conduit 21 included in the heating circuit 11, and an outlet 19d of the first side 19a of the second heat exchanger 19 is connected to an inlet 33a of said condenser 33 via a second connecting conduit 22 included in the heating circuit 11. A circulation pump 43 is arranged in the first connecting conduit 21 and operable to circulate heating liquid between said condenser 33 and the first side 19a of the second heat exchanger 19 through the first and second connecting conduits 21, 22 in the above-mentioned second operating situation when the local heat pump 30 is operated to generate heat for the final heating of the pre-heated tap hot-water, as illustrated with thick lines in Fig 2b. The circulation pump 43 could as an alternative be arranged in the second connecting conduit 22. Thus, in the embodiments illustrated in Figs 2-4, a flow of heating liquid is directed from the output side 30b of the local heat pump 30 to the first side 19a of the second heat exchanger 19 in the second operating situation to thereby allow the second heat exchanger 19 to effect final heating of the preheated tap hot-water in the second operating situation by transferring heat from the heating liquid in this flow of heating liquid to the preheated tap hot-water.

[0038] An accumulator tank 36 may be arranged in the second connecting conduit 22, as illustrated in Fig 3, in order to accumulate heating liquid that is circulating between the condenser 33 of the local heat pump 30 and the first side 19a of the second heat exchanger 19 in the second operating situation.

[0039] In the embodiments illustrated in Figs 2-4, the final-heated tap hot-water is conveyed via a tap hot-water circuit 50 to one or more tapping points 51, which for instance may be provided with hot-water taps. The second side 19b of the second heat exchanger 19 is connected to the tap hot-water circuit 50 in order to allow the tap hot-water circuit 50 to receive tap hot-water that has been subjected to final heating by the second heat exchanger 19. Tap hot-water that has passed the tapping points 51 without being tapped is conveyed back to the second side 19b of the second heat exchanger 19. A circulation pump 52 is arranged in the tap hot-water circuit 50 for circulating the final-heated tap hot-water therein. An accumulator tank (not shown) may also be arranged in the tap hot-water circuit 50, wherein tap hot-water final-heated by the second heat exchanger 19 may be stored in this accumulator tank.

[0040] In the embodiment illustrated in Figs 5a and 5b, the preheated tap hot-water is final heated directly by the local heat pump 30 in the second operating situation. Also in this embodiment, the final-heated tap hot-water is conveyed via a tap hot-water circuit 50' to one or more tapping points 51, which for instance may be provided with hot-water taps. The output side 30b of the local heat pump 30 is connected to the tap hot-water circuit 50' in order to allow transfer of heat from the working medium of the local heat pump 30 to tap hot-water in the tap hot-water circuit 50' via the condenser 33 of the local heat pump for final-heating of the tap hot-water in the second operating situation. Also the second side 19b of the second heat exchanger 19 is connected to the tap hot-water circuit 50' in order to allow the tap hot-water circuit 50' to receive tap hot-water that has been subjected to final heating by the second heat exchanger 19 in the first operating situation. Tap hot-water that has passed the tapping points 51 without being tapped is conveyed back to the output side 30b of the local heat pump 30. A circulation pump 52 is arranged in the tap hot-water circuit 50' for circulating the final-heated tap hot-water therein. An accumulator tank (not shown) may also be arranged in the tap hot-water circuit 50', wherein tap hot-water final-heated by the second heat exchanger 19 or the local heat pump 30 may be stored in this accumulator tank. The second side 19b of the second heat exchanger 19 is connected to the water supply line 20 in series with the second side 18b of the first heat exchanger 18a to thereby allow water preheated in the first heat exchanger 18 to flow from the second side 18b of the first heat exchanger 18 to the tap hot-water circuit 50' via the second side 19b of the second heat exchanger 19 in the first operating situation while being subjected to final heating in the second heat exchanger 19.

[0041] In the embodiment illustrated in Figs 5a and 5b, the water supply line 20 comprises a bypass conduit 20a, through which water preheated in the first heat exchanger 18 may flow directly from the second side 18b of the first heat exchanger 18 to the tap hot-water circuit 50' without passing through the second side 19b of the second heat exchanger 19. In this case, a control valve 47 is arranged in the water supply line 20 for controlling the flow of water through the bypass conduit 20a. This control valve 47 is settable in a first setting position, in which the control valve 47 is configured to direct the flow of water between the second side 18b of the first heat exchanger 18 and the tap hot-water circuit 50' through the second side 19b of the second heat exchanger 19, and a second setting position, in which the control valve 47 is configured to direct the flow of water between the second side 18b of the first heat exchanger 18 and the tap hot-water circuit 50' through the bypass conduit 20a. The electronic control device 40 is configured to control this control valve 47 to assume the first setting position in the first operating situation and the second setting position in the second operating situation.

[0042] In the illustrated embodiments, the first side 19a of the second heat exchanger 19 is connected to the heating circuit 11 in series with the first side 18a of the first heat exchanger 18 to thereby allow heating liquid that has passed through the first side 19a of the second heat exchanger 19 in the first operating situation to be directed into the first side 18a of the first heat exchanger 18 for use in the preheating of the tap hot-water in the first heat exchanger 18.

[0043] In the illustrated embodiments, an outlet 18d of the first side 18a of the first heat exchanger 18 is connected to the return conduit 14 of the heating circuit 11 via a third connecting conduit 23 included in the heating circuit 11 to thereby allow the heating liquid that has passed through the first side 18a of the first heat exchanger 18 to flow to the return conduit 14 via this third connecting conduit 23. In the illustrated examples, a circulation pump 44 is arranged in the third connecting conduit 23 in order to generate a flow of heating liquid through the first sides 18a, 19a of the first and second heat exchangers 18, 19 in the first operating situation, as illustrated with thick lines in Figs 2a and 5a, and a flow of heating liquid through the first side 18a of the first heat exchanger in the second operating situation, as illustrated with thick lines in Figs 2b and 5b.

[0044] In the illustrated embodiments, the input side 30a of the local heat pump 30 is connected to the return conduit 14 of the heating circuit 11, wherein the flow of heating liquid between the return conduit 14 and the input side 30a of the local heat pump 30 is controlled by means of a circulation pump 45. In the illustrated examples, the inlet 32a of the evaporator 32 of the local heat pump 30 is connected to the return conduit 14 via a fourth connecting conduit 24 included in the heating circuit 11, and the outlet 32b of this evaporator 32 is connected to the return conduit 14 via a fifth connecting conduit 25 included in the heating circuit 11. The circulation pump 45 is arranged in the fifth connecting conduit 25, but could as an alternative be arranged in the fourth connecting conduit 24. When the circulation pump 45 is in operation in the second operating situation, heating liquid is made to flow from a first point P1 in the return conduit 14, through the evaporator 32 of the local heat pump 30 and from this evaporator 32 to a second point P2 in the return conduit 14 downstream of the first point P1, as illustrated with thick lines in Figs 2b and 5b.

[0045] In the illustrated embodiments, the first sides 18a, 19a of the first and second heat exchangers 18, 19 are connected to the feed conduit 13 of the heating circuit 11 via a sixth connecting conduit 26 included in the heating circuit 11. From a branching point BP in the sixth connecting conduit 26, the flow of heating liquid in the sixth connecting conduit 26 may be directed to the first side 18a of the first heat exchanger 18 via a first branch 26a of the sixth connecting conduit 26 or to the first side 19a of the second heat exchanger 19 via a second branch 26b of the sixth connecting conduit 26. In the illustrated examples, a control valve 41, 42 is arranged in each branch 26a, 26b in order to control the flow path of the heating liquid from the branching point BP. When the control valve 41 in the first branch 26a is closed and the control valve 42 in the second branch 26b is open, the flow of heating liquid in the sixth connecting conduit 26 is directed to the inlet 19c of the first side 19a of the second heat exchanger 19 via the second branch 26b and further on from the outlet 19d of the first side 19a of the second heat exchanger 19 to the inlet 18c of the first side 18a of the first heat exchanger 18 via a seventh connecting conduit 27 included in the heating circuit 11, as illustrated with thick lines in Figs 2a and 5a. When the control valve 41 in the first branch 26a is open and the control valve 42 in the second branch 26b is closed, the flow of heating liquid in the sixth connecting conduit 26 is directed to the inlet 18c of the first side 18a of the first heat exchanger 18 via the first branch 26a, as illustrated with thick lines in Figs 2b and 5b. As an alternative, the two control valves 41, 42 could be replaced by a control valve in the form of a three-way valve arranged in the branching point BP. In the embodiments illustrated in Figs 2-4, the second branch 26b is connected to the above-mentioned first connecting conduit 21 at a junction point JP, wherein a non-return valve 49 is arranged in the first connecting conduit 21 upstream of the junction point JP in order prevent heating liquid from flowing from the junction point JP towards the output side 30b of the local heat pump 30 in the first operating situation.

[0046] In the embodiment illustrated in Fig 4, the local heating installation 10 comprises a third heat exchanger 38, which has a first side 38a connected to the return conduit 14 of the heating circuit 11 and a second side 38b connected to the water supply line 20 in series with and upstream of the second side 18b of the first heat exchanger 18. The third heat exchanger 38 is configured to preheat the tap hot-water in a first step by transferring heat from the heating liquid in the heating circuit 11 to water in the water supply line 20 and the first heat exchanger 18 is configured to preheat the tap hot-water in a subsequent second step. In the illustrated embodiment, the flow of heating liquid between the return conduit 14 and the first side 38a of the third heat exchanger is controlled by means of a circulation pump 46. In the illustrated example, an inlet 38c of the first side 38a of the third heat exchanger 38 is connected to the return conduit 14 via an eighth connecting conduit 28 included in the heating circuit 11, and an outlet 38d of the first side 38a of the third heat exchanger 38 is connected to the return conduit 14 via a ninth connecting conduit 29 included in the heating circuit 11. The circulation pump 48 is arranged in the ninth connecting conduit 29, but could as an alternative be arranged in the eighth connecting conduit 28. When the circulation pump 46 is in operation, heating liquid is made to flow from a third point P3 in the return conduit 14, through the first side 38a of the third heat exchanger and from the first side 38a of the third heat exchanger to a fourth point P4 in the return conduit 14 downstream of the third point P3. A third heat exchanger 38 may of course also be added in a corresponding manner to the local heating installations 10 illustrated in Figs 2, 3 and 5.

[0047] The invention is of course not in any way restricted to the embodiments described above. On the contrary, many possibilities to modifications thereof will be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention such as defined in the appended claims.

Claims

1. A local heating installation for providing comfort heating and tap hot-water in a building, the local heating installation (10) comprising:

- a heating circuit (11) containing heating liquid, wherein the heating circuit (11) comprises a feed conduit (13) for supply of heating liquid heated under the effect of heat energy produced by one or more heat energy producing devices (3a, 3b) of a central heat production plant (2) and a return conduit (14) for the heating liquid;

- a heat emitting assembly (15) configured to provide comfort heating by heating air within said building while utilizing heat energy derived from the heating liquid of the heating circuit (11), wherein the heat emitting assembly (15) is connected to said feed conduit (13) in order to allow supply of heating liquid to the heat emitting assembly (15) via the feed conduit (13) and connected to said return conduit (14) in order to allow return of heating liquid from the heat emitting assembly (15) via the return conduit (14);

- a first heat exchanger (18), which has a first side (18a) connected to the heating circuit (11) and a second side (18b) connected to a water supply line (20) and which is configured to preheat tap hot-water by transferring heat from the heating liquid in the heating circuit (11) to water in the water supply line (20);

- a local heat pump (30), which has an input side (30a) connected to the feed conduit (13) or the return conduit (14) of the heating circuit (11) and which is capable of generating heat for final heating of the preheated tap hot-water by absorbing heat energy from the heating liquid in the heating circuit (11);

- flow regulating devices (41-45), in the form of one or more control valves (41, 42) and/or one or more circulation pumps (43, 44, 45), for controlling flow paths of the heating liquid in the heating circuit (11); and

- an electronic control device (40) for controlling the local heat pump (30) and said flow regulating devices (41-45), characterized in:

- that the local heating installation (10) comprises a second heat exchanger (19) for final heating of tap hot-water preheated by the first heat exchanger (18), wherein a first side (19a) of the second heat exchanger (19) is connectable to said feed conduit (13) in order to allow the first side (19a) of the second heat exchanger (19) to receive a flow of heating liquid from the feed conduit (13) and wherein a second side (19b) of the second heat exchanger (19) is connected or connectable to the second side (18b) of the first heat exchanger (18) in order to allow the second side (19b) of the second heat exchanger (19) to receive preheated tap hot-water from the first heat exchanger (18);

- that the local heating installation (10) comprises at least one temperature sensor (48) configured to measure a temperature that reflects the temperature (T1) of the heating liquid in said feed conduit (13), wherein the electronic control device (40) is configured to receive measuring values from said at least one temperature sensor (48);

- that the electronic control device (40) in a first operating situation, when it is established by the electronic control device (40) that the temperature (T1) of the heating liquid in said feed conduit (13) is higher than a predetermined threshold temperature (T_th), is configured to keep the local heat pump (30) out of operation and control said flow regulating devices (41-45) to direct a flow of heating liquid from said feed conduit (13) to the first side (19a) of the second heat exchanger (19) to thereby allow the second heat exchanger (19) to effect final heating of the preheated tap hot-water by transferring heat from the heating liquid in this flow of heating liquid to the preheated tap hot-water; and

- that the electronic control device (40) in a second operating situation, when it is established by the electronic control device (40) that the temperature (T1) of the heating liquid in said feed conduit (13) is lower than said threshold temperature (T_th), is configured to control said flow regulating devices (41-45) to prevent a flow of heating liquid from said feed conduit (13) to the first side (19a) of the second heat exchanger (19) and to direct a flow of heating liquid from said feed conduit (13) or said return conduit (14) to the input side (30a) of the local heat pump (30) to thereby allow the local heat pump (30) to generate heat for final heating of the pre-heated tap hot-water by absorbing heat energy from the heating liquid in this flow of heating liquid.

2. A local heating installation according to claim 1, characterized in that said threshold temperature (T_th) is in the range of 52-65 °C, preferably 52-60 °C, and more preferably 52-55 °C.

3. A local heating installation according to claim 1 or 2, characterized in that the first side (19b) of the second heat exchanger (19) is connectable to an output side (30b) the local heat pump (30), wherein the electronic control device (40) is configured to control said flow regulating devices (41-45) to direct a flow of heating liquid from the output side (30b) of the local heat pump (30) to the first side (19a) of the second heat exchanger (19) in said second operating situation to thereby allow the second heat exchanger (19) to effect final heating of the preheated tap hot-water in the second operating situation by transferring heat from the heating liquid in this flow of heating liquid to the preheated tap hot-water.

4. A local heating installation according to claim 3, characterized in that an output (33b) of a condenser (33) of the local heat pump (30) is connected to an inlet (19c) of the first side (19a) of the second heat exchanger (19) via a first connecting conduit (21) included in the heating circuit (11), and an outlet (19d) of the first side (19a) of the second heat exchanger (19) is connected to an inlet (33a) of said condenser (33) via a second connecting conduit (22) included in the heating circuit (11), wherein a circulation pump (43) is arranged in the first or second connecting conduit (21, 22) and operable to circulate heating liquid between said condenser (33) and the first side (19a) of the second heat exchanger (19) through the first and second connecting conduits (21, 22) in said second operating situation.

5. A local heating installation according to claim 3 or 4, characterized in:

- that the local heating installation (10) comprises a tap hot-water circuit (50), in which the final-heated tap hot-water is circulated, and a circulation pump (52) arranged in the tap hot-water circuit (50) for circulating the final-heated tap hot-water therein; and

- that the second side (19b) of the second heat exchanger (19) is connected to the tap hot-water circuit (50) in order to allow the tap hot-water circuit (50) to receive tap hot-water that has been subjected to final heating by the second heat exchanger (19) in said first and second operating situations.

6. A local heating installation according to claim 1 or 2, characterized in:

- that the local heating installation (10) comprises a tap hot-water circuit (50'), in which the final-heated tap hot-water is circulated, and a circulation pump (52) arranged in the tap hot-water circuit (50') for circulating the final-heated tap hot-water therein;

- that the second side (19b) of the second heat exchanger (19) is connected to the tap hot-water circuit (50') in order to allow the tap hot-water circuit (50') to receive tap hot-water that has been subjected to final heating by the second heat exchanger (19) in said first operating situation; and

- that the local heat pump (30) has an output side (30b) connected to the tap hot-water circuit (50') in order to allow transfer of heat from a working medium of the local heat pump (30) to tap hot-water in the tap hot-water circuit (50') in a condenser (33) of the local heat pump for final-heating of the tap hot-water in said second operating situation.

7. A local heating installation according to claim 6, characterized in that the second side (19b) of the second heat exchanger (19) is connected to the water supply line (20) in series with the second side (18b) of the first heat exchanger (18) to thereby allow water preheated in the first heat exchanger (18) to flow from the second side (18b) of the first heat exchanger (18) to the tap hot-water circuit (50') via the second side (19b) of the second heat exchanger (19) in said first operating situation while being subjected to final heating in the second heat exchanger (19).

8. A local heating installation according to claim 7, characterized in:

- that the water supply line (20) comprises a bypass conduit (20a), through which water preheated in the first heat exchanger (18) may flow directly from the second side (18b) of the first heat exchanger (18) to the tap hot-water circuit (50') without passing through the second side (19b) of the second heat exchanger (19); and

- that the local heating installation (10) comprises a control valve (47) that is arranged in the water supply line (20) for controlling the flow of water through said bypass conduit (20a) and that is settable in a first setting position, in which the control valve (47) is configured to direct the flow of water between the second side (18b) of the first heat exchanger (18) and the tap hot-water circuit (50') through the second side (19b) of the second heat exchanger (19), and a second setting position, in which the control valve (47) is configured to direct the flow of water between the second side (18b) of the first heat exchanger (18) and the tap hot-water circuit (50') through said bypass conduit (20a), wherein the electronic control device (40) is configured to control this control valve (47) to assume the first setting position in said first operating situation and the second setting position in said second operating situation.

9. A local heating installation according to any of claims 1-8, characterized in that the first side (19a) of the second heat exchanger (19) is connected to the heating circuit (11) in series with the first side (18a) of the first heat exchanger (18) to thereby allow heating liquid that has passed through the first side (19a) of the second heat exchanger (19) in said first operating situation to be directed into the first side (18a) of the first heat exchanger (18) for use in the preheating of the tap hot-water.

10. A local heating installation according to any of claims 1-9, characterized in that an outlet (18d) of the first side (18a) of the first heat exchanger (18) is connected to said return conduit (14) via a third connecting conduit (23) included in the heating circuit (11) to thereby allow the heating liquid that has passed through the first side (18a) of the first heat exchanger (18) to flow to the return conduit (14) via this third connecting conduit (23).

11. A local heating installation according to any of claims 1-10, characterized in that the input side (30a) of the local heat pump (30) is connected to said return conduit (14), wherein an inlet (32a) of an evaporator (32) of the local heat pump (30) is connected to the return conduit (14) via a fourth connecting conduit (24) included in the heating circuit (11), and an outlet (32b) of said evaporator (32) is connected to the return conduit (14) via a fifth connecting conduit (25) included in the heating circuit (11).

12. A local heating installation according to any of claims 1-11, characterized in that the local heating installation (10) comprises a third heat exchanger (38), which has a first side (38a) connected to said return conduit (14) and a second side (38b) connected to the water supply line (20) in series with and upstream of the second side (18b) of the first heat exchanger (18), wherein the third heat exchanger (38) is configured to preheat the tap hot-water in a first step by transferring heat from the heating liquid in the heating circuit (11) to water in the water supply line (20) and the first heat exchanger (18) is configured to preheat the tap hot-water in a subsequent second step.

13. A local heating installation according to any of claims 1-12, characterized in that the heat emitting assembly (15) comprises one or more radiators (16).

14. A heating system comprising a central heat production plant (2) with one or more heat energy producing devices (3a, 3b), characterized in that the heating system (1) comprises one or more local heating installations (10) according to any of claims 1-13 for providing comfort heating and tap hot-water in a respective building or part of a building by utilizing heat energy produced by said heat energy producing devices (3a, 3b).

15. A heating system according to claim 14, characterized in that the heating system (1) comprises two or more such local heating installations (10) and a distribution grid (5) for supplying heating liquid heated under the effect of heat energy produced by said heat energy producing devices (3a, 3b) to the local heating installations (10), wherein the local heating installations (10) are connected to the distribution grid (5) in parallel with each other.

Drawing