EP3225922B1 - Cooling, air-conditioning or heating system - Google Patents

Description

The invention relates to a cooling, air conditioning or heating system for a building based on the heat pump principle and using outside air as a source of thermal energy. The system is of the type with separate heat exchange units in which, on the one hand, the compressor, the expansion member and the first exchanger in which the outside air circulates and, on the other hand, the second exchanger are distributed in two separate heat exchange units at a distance from each other.

When such a system is installed for the purpose of cooling, air conditioning or heating a building (dwelling, etc.), one of the heat exchange units, called the outdoor unit, is placed outside the building while the The other unit is placed inside the building.

Generally, this type of outdoor unit has an evaporator, an air inlet on a first face and an air outlet on a second face opposite the first.

It is known that on heat pumps, defrost can be provided by a cycle reversal by means of a 4-way valve on the refrigeration circuit. Said valve performs the changeover between the evaporator and the condenser of the refrigeration circuit. During this operation, energy must be supplied to the condenser which has turned into an evaporator. Other examples are disclosed in the documents EP 2103890A1 and EP2940407A1 .

Currently, the strategy in the event of defrost of the evaporator of the outdoor unit is to reverse the refrigeration cycle and to take the defrost energy from at least one hydraulic circuit of the heating network.

It is known that on the so-called 2-service devices ensuring both sequentially the heating function and the domestic hot water production function, a 3-way directional valve is used to ensure the switching of the hydraulic circuits to the condenser, the latter. this can be irrigated by the heating circuit or the sanitary circuit.

Usually, the switching of a 3-way valve between the DHW circuit (Domestic Hot Water) and the heating circuit (also providing cooling and air conditioning functions) is used for this. function, on devices providing these two services. The use of 2 pumps can also perform the same function.

This strategy works well with an exchanger (condenser) which has a large volume of water, such as for example a coaxial exchanger in a buffer tank of the type described in the application. EP2080975 , but presents on the other hand risks of freezing with low volume heat exchangers, of the plate heat exchanger type for example and / or very low volume heating installations.

In the latter case, the hydraulic design of the installation must provide for a system ensuring circulation of the heating fluid and a minimum volume thereof in all situations.

A usual solution is to indicate a minimum volume of water for the installation and if necessary to place a buffer tank on the return of the condenser. The operational safety of the device is also associated with a water flow control. The rules of the art also stipulate that a heating installation with a centralized controller, which is for example the case of a heat pump system, must include at least one heat emitter, usually a radiator, fitted with a non-thermostatic valve, which does not prevent the user from closing said valve but avoids its automatic closing by raising the air temperature in the room.

• Si le débit d'eau sur l'installation est faible ou nul, dans le cas par exemple d'une vanne thermostatique et de robinets fermés, il existe un risque de gel de l'échangeur (condenseur) lors du dégivrage. Le risque augmente sur des installations à faible volume d'eau. Ce risque est accentué en mi saison ou dans les habitations sensibles à l'ensoleillement ou par la présence d'appareils de chauffage individuels impliquant par exemple du bois : dans ce cas, en l'absence de besoin de chauffage des locaux, le basculement en dégivrage intervient souvent lors d'une charge sanitaire et le circuit de chauffage peut être complètement fermé.
• Lors d'une mise en route par temps froid, il donc est nécessaire de préchauffer la boucle de chauffage avec les appoints électrique afin de garantir la disponibilité de suffisamment d'énergie pour un éventuel dégivrage. Ceci est contraignant, mal vécu par l'installateur et source de gaspillage d'énergie.

This arrangement has a few drawbacks:

• If the water flow through the installation is low or zero, for example in the case of a thermostatic valve and closed taps, there is a risk of the exchanger (condenser) freezing during defrost. The risk increases on installations with a low volume of water. This risk is accentuated in mid-season or in homes sensitive to sunlight or by the presence of individual heating devices involving, for example, wood: in this case, in the absence of the need for space heating, switching to defrost often occurs during a domestic hot water load and the heating circuit can be completely closed.
• When starting in cold weather, it is therefore necessary to preheat the heating loop with the electrical back-ups in order to guarantee the availability of sufficient energy for a possible defrost. This is restrictive, badly experienced by the installer and a source of energy waste.

A cooling, air conditioning or heating system according to the invention overcomes the drawbacks noted in the state of the art, by proposing in particular to ensure the defrosting of the outdoor unit, regardless of the geometry and the characteristics. the hydraulic environment of the condenser.

For the remainder of the description, it is important to specify that the expressions “defrosting the outdoor unit” and “defrosting the evaporator” are equivalent.

The subject of the invention is a system for cooling, air conditioning or heating a building comprising a circuit for modifying the temperature of said building and a hot water heating circuit provided with a hot water tank, said system being based on the principle of the heat pump using air as an external source and comprising an external heat exchange unit equipped with an evaporator and an internal unit having a condenser and intended to heat a secondary fluid circulating alternately in the heating circuit heating and the hot water heating circuit where it ensures the heating of a tertiary fluid supplying the tank, through an exchanger thermally connecting the secondary and tertiary fluids.

The main characteristic of a system according to the invention is that it comprises an automatic control device making it possible, during evaporator defrosting operations carried out by a cycle inversion of the outdoor unit, to stop the circulation of the fluid. secondary in the temperature modification circuit, and to redirect said secondary fluid to the exchanger in order to maintain the secondary fluid at a certain temperature by means of a withdrawal of the heat energy necessary for said cycle in the hot water tank via the condenser of the indoor unit. The building temperature modification circuit can for example consist of a heating circuit, a cooling circuit or an air conditioning circuit. Depending on its use, the temperature modification circuit can either lower or increase the temperature of the building. However, such a temperature modification circuit is essentially used as a heating circuit in the context of the present invention.

The outdoor heat exchange unit provides heat exchange with the outdoor air and includes at least one heat exchanger in the form of an evaporator. A system according to the invention is thus able to ensure defrosting of this evaporator by drawing off the heat energy from the hot water tank via the condenser of the internal unit. Defrosting of this evaporator is usually carried out by means of the indoor unit condenser connected to the temperature modification circuit, which presents a risk of freezing if it is too small. By using the hot water stored in the tank, the condenser of the temperature modification circuit is no longer exposed to freezing. However, it is not excluded that the temperature modification circuit can be totally or partially substituted for the domestic hot water circuit to provide transient defrosting of the evaporator of the outdoor heat exchange unit. . Indeed, the fact of ensuring the defrost of the evaporator mainly with the hot water circulation circuit does not mean that this defrost cannot be carried out with the temperature modification circuit, during clearly identified periods. . Preferably, the temperature modification circuit is a hydraulic circuit. Preferably, a control unit controls the various hot water flows present in the building, in particular in order to convey the hot water stored in the balloon to the condenser transformed into an evaporator. Advantageously, the hot water circuit is a domestic hot water circuit.

Preferably, a system according to the invention comprises a directional valve capable of managing the two circuits, the defrosting of the evaporator of the outdoor unit being carried out jointly with the reversal of the refrigeration cycle, by tilting the valve making it possible to redirect the secondary fluid to the heat exchanger in communication with the tertiary fluid of the balloon, ensuring the permutation of the hot sources of said cycle. In this way, when a need for evaporator defrost is detected, simultaneously with the cycle reversal of the outdoor unit, a control unit controls the valve so as to send hot water stored in the tank. of domestic water to the condenser of the circuit transformed into an evaporator by the cycle inversion, in order to transmit to it the energy necessary for the defrost of the evaporator of the outdoor unit, which functions as a condenser during the defrost. Advantageously, the hot water stored in the tank can be sent to the condenser via an intermediate exchanger, such as for example a coil.

According to another preferred embodiment of a system according to the invention, said system comprises two separate pumps able to manage the two circuits, the defrost of the evaporator of the outdoor unit being carried out jointly with the reversal of the refrigeration cycle. , by switching the pump of the temperature modification circuit to the pump of the hot water circuit making it possible to redirect the secondary fluid to the heat exchanger in communication with the tertiary fluid of the tank, ensuring the changeover of the hot sources of said cycle.

Advantageously, a system according to the invention comprises means for controlling the temperature of the water stored in the balloon. In this way, the temperature of the water present in the tank can be adjusted as necessary in relation to the needs of the moment, in terms of defrosting.

Another subject of the invention is a method for defrosting an evaporator of an outdoor unit of a system according to the invention.

• une étape de basculement des deux circuits vers le circuit d'eau chaude,
• une étape de dégivrage par inversion du cycle, de l'évaporateur de l'unité d'échange thermique extérieure avec l'énergie apportée au condenseur par l'eau chaude stockée dans le ballon.

The main characteristic of a system according to the invention is that it comprises the following steps,

• a switching step of the two circuits to the hot water circuit,
• a cycle reversal defrost step of the evaporator of the external heat exchange unit with the energy supplied to the condenser by the hot water stored in the tank.

It should be noted that the switching of the two circuits to the hot water circuit can for example be carried out by means of a valve and / or pumps.

Advantageously, a method according to the invention comprises a step of controlling the temperature of the sanitary water stored in the tank. This step of controlling the temperature of the domestic hot water stored in the tank aims to verify that said water is indeed able to ensure the defrosting of the evaporator in a complete and satisfactory manner. The control step can for example be carried out by means of measurements, carried out with conventional temperature probes.

Preferably, a method according to the invention comprises a step of preliminary heating of the water present in the tank, if the temperature controlled in the tank is below a predetermined threshold value. Indeed, if the control step reveals that the temperature of the water is not high enough, then a defrosting process according to the invention implements an additional step of heating the water to bring it to a temperature. sufficient temperature and enable it to ensure satisfactory defrosting of the evaporator.

Preferably, the stage of preliminary heating of the balloon is carried out by means of an electrical resistance device. It is a simple, proven and well-mastered heating method.

Advantageously, if the temperature controlled in the tank is below a predetermined threshold value, said method comprises a step of using the temperature modification circuit as a hot source. to ensure defrosting of the evaporator of the outdoor unit. Indeed, if the conditions are not met at the level of the hot water tank, then the temperature modification circuit can be requested to temporarily ensure the defrost of the evaporator, while waiting for the hot water tank to become operational.

Advantageously, the threshold temperature of the tank depends on at least one parameter to be chosen from the characteristics of the external heat exchange unit, the capacity of the tank and a condenser placed on the water circuit and the circuit for modifying the temperature. temperature. This threshold temperature is set taking into account the environment of the temperature modification circuit and the domestic hot water, the structural and functional characteristics of the external heat exchange unit, the tank capacity and the characteristics. of the indoor unit condenser.

Another object of the invention is a building comprising a system in accordance with the invention and allowing the implementation of a method according to the invention.

The main characteristic of a building according to the invention is that the step of defrosting the outdoor unit is carried out from a control unit which is able to select the temperature modification circuit or the circuit d. hot water to ensure said defrosting. Such a building thus has a double possibility of defrosting the outdoor unit, one via the temperature modification circuit, the other via the hot water circuit. Advantageously, these two circuits can thus be used alternately, to ensure the same phase of defrosting the evaporator. According to another embodiment, one of the two circuits may be preferred to the other circuit to ensure the entire defrosting phase, as a function of economic parameters or for reasons of efficiency and yield. Indeed, in the event of a forecast of a strong need for hot water, it is the temperature modification circuit which will be favored to ensure the defrost of the evaporator and thus to preserve the hot water for its use. original.

Advantageously, the selection of the circuit is a function of at least one parameter to be chosen from among the temperature of the hot water, the temperature of the temperature modification circuit, the heating flow rate, and the time range of use of said circuit.

• Il rend moins sensible les pompes à chaleur à une mauvaise définition du réseau hydraulique qui risquerait d'entrainer une casse du condenseur par gel, par exemple en cas d'absence de soupape différentielle ou by-pass, ou de boucle ouverte sur un réseau avec radiateurs (têtes thermostatiques),
• Il garantit le débit d'eau et évite le gel de l'échangeur lors d'un dégivrage,
• S'il est placé sur un réseau à très faible volume d'eau, il est possible de trouver l'énergie du dégivrage dans le ballon d'eau chaude sanitaire,
• Sa mise en œuvre peut être facilitée par temps froid au moyen d'une stratégie reposant sur un chauffage préliminaire du ballon d'eau chaude sanitaire, puis sur une autorisation de fonctionnement du module thermodynamique pour le chauffage, même si la température du circuit hydraulique de chauffage est basse. Il n'existe ainsi plus de risque de gel dans l'échangeur lors du dégivrage,
• Il évite un inconfort provoqué par la chute de température de départ en mode chauffage lors des dégivrages (particulièrement avec des générateurs à faible inertie ou de type ventilo-convecteurs en combinaison ou non avec des faibles volumes),
• Lors des périodes de production d'eau chaude sanitaire uniquement, par exemple à mi saison, il permet d'éviter d'envoyer dans le circuit de chauffage le volume d'eau à assez haute température de l'échangeur au moment du basculement de la vanne en mode dégivrage, et donc de provoquer des gênes utilisateurs pour des trains de chaleur dans les radiateurs alors qu'il n'y a pas de besoin chauffage,
• Il améliore l'efficacité de la production d'eau chaude sanitaire : l'énergie contenue dans l'échangeur au moment du basculement de la vanne en mode dégivrage est envoyé dans le circuit de modification de la température et est donc perdue pour l'eau chaude sanitaire. Une partie est donc récupérable par le ballon. De plus, avec un échangeur incluant un ballon tampon (coaxial) et selon les conditions du circuit de chauffage, l'échangeur est refroidi plus que nécessaire par le flot de retour chauffage. On peut donc envisager de moduler le dégivrage entre 0 - 100 % sur l'eau chaude sanitaire ou le circuit de modification de la température afin de minimiser la consommation globale du système. Cette logique doit être associée à une sécurité du débit du circuit de modification de la température (basculement de la vanne sur l'eau chaude sanitaire).
• Les cycles de dégivrage sur ECS, accentueront la stratification du ballon et contribueront à l'amélioration de l'efficacité sur les relances.

A cooling, air conditioning or heating system according to the invention has the following advantages,

• It makes the heat pumps less sensitive to a poor definition of the hydraulic network which could cause the condenser to break due to freezing, for example in the absence of a differential or bypass valve, or of an open loop on a network with radiators (thermostatic heads),
• It guarantees the water flow and prevents the exchanger from freezing during defrosting,
• If it is placed on a network with very low water volume, it is possible to find the defrost energy in the domestic hot water tank,
• Its implementation can be facilitated in cold weather by means of a strategy based on preliminary heating of the domestic hot water tank, then on an operating authorization of the thermodynamic module for heating, even if the temperature of the hydraulic circuit of heating is low. There is therefore no longer any risk of freezing in the exchanger during defrosting,
• It avoids discomfort caused by the drop in flow temperature in heating mode during defrosts (particularly with low inertia generators or fan coil type generators in combination or not with low volumes),
• During periods of domestic hot water production only, for example in mid-season, it makes it possible to avoid sending into the heating circuit the volume of water at a high enough temperature from the exchanger when the heat exchanger is switched. valve in defrost mode, and therefore cause inconvenience to users for heat trains in the radiators when there is no need for heating,
• It improves the efficiency of domestic hot water production: the energy contained in the exchanger when the valve is switched to defrost mode is sent to the temperature modification circuit and is therefore lost for the water. domestic hot water. A part is therefore recoverable by the ball. In addition, with an exchanger including a buffer tank (coaxial) and depending on the conditions of the heating circuit, the exchanger is cooled more than necessary by the heating return flow. It is therefore possible to envisage modulating the defrost between 0 - 100% on the domestic hot water or the temperature modification circuit in order to minimize the overall consumption of the system. This logic must be associated with a flow rate safety device for the temperature modification circuit (switching the valve to domestic hot water).
• The defrost cycles on DHW, will accentuate the stratification of the tank and will contribute to the improvement of the efficiency on the relaunches.

• La figure 1 est une vue schématique d'un bâtiment selon l'invention comprenant un système de dégivrage selon l'invention.

A detailed description is given below of a preferred embodiment of a building according to the invention as well as of a de-icing process according to the invention with reference to figure 1 .

• The figure 1 is a schematic view of a building according to the invention comprising a de-icing system according to the invention.

With reference to the figure 1 , a building 1 according to the invention comprises a cooling, air conditioning or heating system comprising a circuit in which a secondary fluid circulates, said circuit comprising a heating circuit 2 and a domestic hot water circuit 3 in communication with a heat exchanger 12 immersed in a domestic hot water tank 4, in which a tertiary fluid 13 circulates, said system being based on the principle of the heat pump, using air as an external source. The tertiary fluid 13 therefore supplies the hot water tank 4 from a source forming an integral part of the water supply network of the building 1. This heat pump also uses a thermodynamic cycle based on compression, condensation, the expansion and evaporation of a fluid primary 11, such as for example R410A, and is intended to heat the secondary fluid of the heating circuit 2 and of the domestic hot water circuit 3, and the tertiary fluid 13 of the tank 4.

Such a system conventionally comprises a three-way valve 5 capable of controlling the secondary fluid between the heating circuit 2 and the domestic hot water circuit 3 towards the tertiary fluid 13 of the tank 4. The building 1 comprises an exchange unit 6. external thermal allowing to ensure a thermal exchange with the outside air, said unit 6 comprising at least one heat exchanger in the form of an evaporator and a cycle reversal valve. Said building 1 also comprises an indoor unit having a condenser 8. The heating circuit 2 comprises the condenser 8 and is able to supply hot water to heating elements such as for example radiators 10 of building 1. The evaporator of the The outdoor unit 6 being liable to undergo phases of accumulation of frost during the various operating phases of the cooling, air conditioning or heating system, must undergo defrost phases in order to remain operational.

Until now, these defrosting phases were provided by the condenser 8 of the indoor unit. However, it turned out that when said condenser 8 had a small volume, it risked freezing or degrading the temperature in the heating circuit 2.

• une étape de contrôle de la température de l'eau stockée dans le ballon 4 afin de comparer ladite température à une température seuil prédéterminée. Cette étape peut consister en une étape de mesure de la température de l'eau stockée dans le ballon 4, au moyen de sondes de température conventionnelles. Si la température seuil n'est pas atteinte, une étape de préchauffage du ballon 4 peut être réalisée au moyen par exemple de résistances chauffantes 9 conventionnelles. Selon la logique choisie, une vérification des conditions de fonctionnement du circuit de chauffage 2 peut également avoir lieu afin d'autoriser le fonctionnement thermodynamique.
• une étape de détection d'un besoin en dégivrage de l'évaporateur de l'unité extérieure 6,
• une étape de dégivrage de l'évaporateur de l'unité extérieure 6 par une inversion de cycle de ladite unité extérieure 6. Lors de cette étape de dégivrage, la vanne 5 est pilotée par l'unité de commande de manière à arrêter la circulation du fluide secondaire dans le circuit de chauffage 2, et de rediriger ledit fluide secondaire vers l'échangeur 12 afin de maintenir le fluide secondaire à une certaine température au moyen d'un prélèvement de l'énergie calorifique nécessaire audit cycle dans le ballon 4 d'eau chaude via le condenseur 8 de l'unité interne. Suite à cet arrêt, la vanne 5 fait basculer le fluide secondaire vers le circuit 3 d'eau chaude sanitaire et envoie cette eau chaude vers le condenseur 8, conjointement à l'inversion du cycle frigorifique de l'unité extérieure 6. Ainsi, le dégivrage de l'unité extérieure est assuré par un prélèvement de l'énergie calorifique dans le ballon 4 d'eau chaude sanitaire,

A method of defrosting the outdoor unit according to the invention uses the condenser 8, the heat exchanger 12 and the tank 4 for domestic hot water. It is assumed that such a method is driven by a control unit. Such a method comprises the following steps,

• a step of controlling the temperature of the water stored in the tank 4 in order to compare said temperature with a predetermined threshold temperature. This step may consist of a step of measuring the temperature of the water stored in the tank 4, by means of conventional temperature probes. If the threshold temperature is not reached, a step of preheating the tank 4 can be carried out at means, for example, of conventional heating resistors 9. Depending on the chosen logic, a check of the operating conditions of the heating circuit 2 can also take place in order to authorize thermodynamic operation.
• a step of detecting a need for defrosting of the evaporator of the outdoor unit 6,
• a step of defrosting the evaporator of the outdoor unit 6 by a cycle inversion of said outdoor unit 6. During this defrosting step, the valve 5 is controlled by the control unit so as to stop the circulation of the secondary fluid in the heating circuit 2, and to redirect said secondary fluid to the exchanger 12 in order to maintain the secondary fluid at a certain temperature by means of a withdrawal of the heat energy necessary for said cycle in the tank 4 of hot water via condenser 8 of the indoor unit. Following this shutdown, the valve 5 switches the secondary fluid to the domestic hot water circuit 3 and sends this hot water to the condenser 8, together with the reversal of the refrigeration cycle of the outdoor unit 6. Thus, the defrosting of the outdoor unit is ensured by taking heat energy from the domestic hot water tank 4,

The defrosting process described above is carried out exclusively by using, at the hot source of the refrigeration circuit, hot water stored in tank 4. It should be noted that such a process is controlled by a suitable control unit. to take into account all the parameters inherent in the operation of the tank 4, such as for example the temperature, the pressure and the volume of the water present in the said tank 4, as well as the parameters characterizing at a given moment, all the different elements constituting the heat pump, and in particular the outdoor unit 6. This control unit also allows the valve 5 to be controlled in order to operate the heating circuit 2 and / or the domestic hot water circuit 3.

Since building 1 has a heating circuit 2 and a domestic hot water circuit 3, the defrosting of the outdoor unit 6 can be carried out using the said two circuits as a hot source indifferently 2, 3. In this way, the two circuits 2, 3 can be used alternately over a given period, to ensure the same defrost phase for the outdoor unit 6 over said period. According to another alternative use of said circuits 2, 3, only one of said circuits 2, 3 is retained to ensure the defrosting of the outdoor unit 6, the choice of said circuit 2, 3 being dictated by constraints, such as for example the forecast of significant sanitary use, significant heating of building 1, for example in cold weather.

Claims (13)

1. A cooling, air-conditioning or heating system for a building (1) comprising a circuit for modifying the temperature of said building (2) and a hot water heating circuit (3) equipped with a hot water tank (4), said system being based on the principle of the heat pump using air as outside source and including an external heat exchange unit (6) provided with an evaporator and an internal unit having a condenser (8) and intended to heat a secondary fluid alternatively circulating in the temperature modification circuit (2) and the hot water heating circuit (3) where it ensures the heating of a tertiary fluid (13) supplying the tank (4), through an exchanger (12) thermally connecting the secondary and tertiary fluids, characterized in that it comprises an automatic control device configured, during deicing operations of the evaporator done by a cycle inversion of the external unit (6), to stop the circulation of the secondary fluid in the temperature modification circuit (2), and to redirect said secondary fluid toward the exchanger (12) so as to keep the secondary fluid at a certain temperature using a withdrawal of the heat energy necessary for said cycle in the hot water tank (4) via the condenser (8) of the internal unit.
2. The system according to claim 1, characterized in that the heat exchanger (12) is submerged in the hot water tank (4).
3. The system according to any one of claims 1 or 2, characterized in that it comprises a selection valve (5) able to manage the two circuits (2, 3), and in that the deicing of the evaporator of the external unit (6) is done jointly with the inversion of the refrigeration cycle, by switching of the valve (5) making it possible to redirect the secondary fluid toward the exchanger (12) in communication with the tertiary fluid (13) ensuring the switching of the hot sources of said cycle.
4. The system according to any one of claims 1 or 2, characterized in that it comprises two separate pumps able to manage the two circuits (2, 3), and in that the deicing of the evaporator of the external unit (6) is done jointly with the inversion of the refrigeration cycle, by switching from the pump of the temperature modification circuit (2) toward the pump of the hot water circuit (3) making it possible to redirect the secondary fluid toward the exchanger (12) in communication with said tertiary fluid (13) ensuring the switching of the hot sources of said cycle.
5. The system according to any one of claims 1 to 4, characterized in that it comprises means for controlling the temperature of the water stored in the tank (4).
6. A method for deicing an evaporator of an external unit (6) of the system according to any one of claims 1 to 5, characterized in that it comprises the following steps:

   - a step for switching the circuits (2, 3) to the hot water circuit (3),

   - a step for deicing by inversion of the cycle, of the evaporator of the external heat exchange unit (6) with the energy contributed to the condenser (8) by the hot water stored in the tank (4).
7. The deicing method according to claim 6, characterized in that it comprises a step for controlling the temperature of the water stored in the tank (4).
8. The deicing method according to claim 7, characterized in that it comprises a step for preliminary heating of the water present in the tank (4), if the temperature controlled in the tank (4) is below a predetermined threshold value.
9. The deicing method according to claim 8, characterized in that the step for preliminary heating of the tank (4) is done using an electrical resistance device (9).
10. The deicing method according to claim 9, characterized in that if the temperature controlled in the tank (4) is below a predetermined threshold value, said method comprises a step for using the temperature modification circuit (2) as heat source to ensure the deicing of the evaporator of the external unit (6).
11. The deicing method according to any one of claims 7 to 10, characterized in that the threshold temperature of the tank (4) depends on at least one parameter to be chosen among the characteristics of the external heat exchange unit (6), the capacity of the tank (4) and a condenser (8) placed on the water circuit (3) and the temperature modification circuit (2).
12. A building (1) comprising a system according to any one of claims 1 to 5 allowing the implementation of a method according to any one of claims 5 to 10, characterized in that the step for deicing of the external unit (6) is carried out from a control unit which is able to select the temperature modification circuit (2) or the hot water circuit (3) in order to perform said deicing.
13. The building according to claim 12, characterized in that the selection of the circuit (2, 3) depends on at least one parameter to be chosen among the temperature of the hot water, the heating rate, the temperature of the temperature modification circuit (2) and the usage time range of said circuit (2, 3).

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