IT202200023796A1 - HEAT PUMP SYSTEM INCLUDING ONE OR MORE DEVICES DESIGNED TO BLOCK ANY REFRIGERANT LOSSES - Google Patents

Description

DESCRIPTION

attached to an application for a Patent for an Industrial Invention entitled:

?HEAT PUMP SYSTEM INCLUDING ONE OR MORE? DEVICES DESIGNED TO BLOCK ANY REFRIGERANT LEAKS?

DESCRIPTION

The subject of the present invention is a heat pump system for heating/cooling environments and/or for the production of sanitary water, preferably operating with low environmental impact refrigerants.

More precisely, the object of the present invention is a heat pump system for heating/cooling the environment and/or for the production of sanitary water, designed to prevent any refrigerant leaks from spreading internally to the environment in which said heat pump system is installed and/or operates.

More precisely, the object of the present invention is a heat pump system for room heating/cooling functions and/or for the production of sanitary water comprising one or more devices suitable for preventing said possible refrigerant leaks from reaching the room heating and/or sanitary water production system.

The invention therefore fits, without any limiting intent, into the sector of heat pump air conditioning systems for residential and/or industrial/commercial (or similar) buildings, where "conditioning" is to be understood indifferently as "heating" or "cooling", preferably achieved through electrical power.

Naturally, nothing prevents the heat pump system of the invention from being extended, with minimal adaptations within the reach of a technician in the field, to sectors similar to those of heating and/or cooling systems, for example to the field of heat pumps for the production of sanitary water.

It is known that a heat pump system includes at least:

- a ?refrigeration circuit? in which a refrigerant is evaporated at low temperature, brought to high pressure, condensed and finally brought back to an evaporation pressure, and

- a ?conditioning circuit? of a technical fluid, preferably water or similar, usable for heating/cooling the environment via radiators, floor radiant panels, fan coils or similar, and/or for the production of domestic hot water via special heat accumulators, e.g. hot water boilers.

Typically, the refrigeration circuit and the air conditioning circuit share at least one heat exchanger in which the heat exchange between the respective refrigerant and technical fluids takes place.

More precisely, when a heat pump system is used for space heating and/or domestic hot water, the heat exchanger acts as a condenser.

Conversely, if the same heat pump system operates in cooling mode, the heat exchanger acts as an evaporator.

It is known that the development of heat pumps faces a variety of technical and environmental challenges.

On the one hand, we want the heat pump to continue to operate as efficiently as possible, while on the other, we increasingly want to avoid the use of highly polluting refrigerants in order to reduce environmental risks (e.g. to combat phenomena such as global warming).

To meet these goals, the most polluting refrigerants, such as the common R410A, are gradually being replaced with others with a low environmental impact (i.e. with a low "Global Warming Potential" or "GWP"). For example, heat pumps are increasingly operating with refrigerants belonging to the group of hydrofluorocarbons and/or aliphatic hydrocarbons such as, without any limitation, propane R290 (chemical formula: C3H8) or R32 (a difluoromethane with the chemical formula CH2F2).

These refrigerants (or others belonging to the same families or similar groups), although low environmental impact, are not free from problems.

It is known, in fact, that low environmental impact refrigerants are, in general, highly flammable.

Therefore, when switching from traditional refrigerants to low GWP ones, it was necessary to pay more attention to their flammability and related issues.

For example, it has become necessary to prevent refrigerant leaks, caused by possible defects and/or breakages of one or more components of the heat pump system, from reaching and/or spreading internally to the installation and/or use environment (e.g., in a room of a building or in a technical room), where the formation and accumulation of high concentrations of refrigerant, potentially flammable and/or explosive, would pose risks to the safety of users and/or to the structural integrity of buildings.

To avoid such dangers, the most recent heat pump systems using low GWP refrigerants have been appropriately designed to block any refrigerant leaks and escapes before they reach the air conditioning circuit and spread within the environment where the heat pump system is installed and/or used.

For example, said heat pump system has been equipped with a deaerating device capable of stopping the flow of the technical fluid (e.g. technical water) towards the air conditioning circuit in the presence of refrigerant leaks and of preventing their diffusion in the direction of the operating flow, or in the opposite direction, in any case capable of preventing said refrigerant leaks from reaching the pipes, manifolds, valves, radiators, fan coils or any other device used to create the distribution circuit of the technical fluid inside a building.

Since it will be recalled several times in the course of this discussion, it is specified that by "operating flow" or "operating direction" is meant the direction normally imparted to the technical fluid by a circulation pump of the air conditioning circuit when the heat pump system operates in heating and/or cooling conditions (for greater clarity, see also fig. 1, where, by way of a non-limiting example, said "operating flow or direction" is represented by the arrow F).

The technical document DE102020103743B4 shows, by way of example, a known deaerating device of the type comprising a float suitably designed to interrupt the operating flow of the technical fluid when the amount of refrigerant leaks is greater than a predefined and normally tolerated value.

As an additional safety measure, the said degasser device can be located, or at least directly communicated, with the external environment so as to allow the discharge of said refrigerant leaks into the atmosphere.

These heat pump systems can be further equipped with special and well-known valves, generally non-return valves (also called ?check valves? or ?anti-return valves?) which prevent said refrigerant leaks and escapes from flowing towards the air conditioning circuit in the opposite direction to that of the technical fluid's operation, or in contrast to the circulation pump.

This measure is also shown and described in the same document DE102020103743B4 where, in fact, a well-known check valve is positioned in the air conditioning circuit between the circulation pump and the heat exchanger set up for the heat exchange between refrigerant and technical fluid.

While on the one hand the use of a check valve increases the safety of a heat pump system against possible refrigerant leaks, on the other hand it introduces and generates strong localized pressure losses and therefore a significant resistance to the circulation of the technical fluid in the air conditioning circuit, consequently worsening the efficiency of the entire system.

Equally well known is how the refrigerant circuit operates at higher pressures than the air conditioning circuit.

There is therefore the possibility that high-pressure refrigerant leaks (even in the order of a few dozen bar) could generate pressure peaks which, propagating along the air conditioning circuit, could damage pipes and/or components (e.g. the secondary side of the exchanger, the circulation pump, the radiators/radiant panels, etc.), generally tested and approved to work at maximum pressures of 3 bar.

Furthermore, in the event of leaks, the check valve (or similar non-return devices), by preventing the flow of refrigerant through the valve itself, does not allow its expansion in the air conditioning circuit, preventing an effective and rapid "absorption" of the aforementioned pressure peaks; this can increase the risk of breakages and/or malfunctions.

The purpose of this invention is to overcome this type of inconvenience by providing a low environmental impact heat pump system for heating/cooling the environment and/or for the production of sanitary water comprising at least one highly efficient device capable of preventing any refrigerant leaks from spreading internally to the installation and/or use environment.

A further purpose of the present invention, at least for one of its executive variants, is to provide a low environmental impact heat pump system for room heating/cooling functions and/or for the production of sanitary water in which said at least one device capable of intercepting and blocking said possible refrigerant leaks also acts as an element for compensating for pressure peaks deriving from said refrigerant leaks.

A further purpose of the present invention, at least for one of its executive variants, is to provide a low environmental impact heat pump system for room heating/cooling functions and/or for the production of sanitary water in which said at least one device capable of intercepting and blocking said possible refrigerant leaks introduces a substantially negligible resistance to the flow of the technical fluid of the heat pump system itself, or low and/or limited pressure drops.

A further purpose of the present invention, at least for one of its executive variants, is to provide a low environmental impact heat pump system for room heating/cooling functions and/or for the production of sanitary water without check valves.

These and other purposes, which will become clear later, are achieved with a heat pump system compliant with the provisions of the independent claims.

Further purposes may also be achieved by the additional features of the dependent claims.

Further features of the present invention will be better highlighted by the following description of a preferred embodiment, in accordance with the patent claims and illustrated, purely by way of example and not by way of limitation, in the attached drawings, in which:

- fig. 1 schematically shows a heat pump system for room heating/cooling functions and/or for the production of sanitary water according to the invention;

- figures 2a and 2b show, in schematic form, a detail of the heat pump system of fig. 1 according to a first and second operating configuration.

The characteristics of at least one preferred variant of the heat pump system for room heating/cooling functions and/or for the production of sanitary water of the invention are now described, using the references contained in the figures.

With 1 ? therefore, the heat pump system of the invention, as a whole, is indicated, which can be used for heating and/or cooling functions in a domestic or non-domestic environment (e.g. commercial or industrial) and/or for the production of sanitary water, for example domestic hot water.

As already partially mentioned, the heat pump system 1 shows a first circuit 2 in which a refrigerant fluid circulates which is evaporated at low pressure, brought to high pressure, condensed and finally brought back to an evaporation pressure, and a second circuit 3 crossed by a technical fluid, preferably technical water, which can be used for heating/cooling the environment and/or for the production of sanitary water.

From now on, for the sake of simplicity, the first and second circuits of the heat pump system 1 of the invention will be respectively called "refrigeration circuit 2" and "conditioning circuit 3", where, as already anticipated, "conditioning" is to be understood indifferently as both the cooling/heating function of a room and that of heating sanitary water.

In the course of this discussion, the term refrigerant will also be understood, without any limiting intent, to mean a refrigerant with low environmental impact (e.g., low GWP - Global Warming Potential) which, as mentioned, presents a greater risk of flammability, such as, for example, the well-known R290 (Propane), R32 (Difluoromethane), or similar/related refrigerants.

As shown in fig. 1, the refrigeration circuit 2 comprises, connected to each other by means of special pipes:

- at least one first heat exchanger 20,

- at least one second heat exchanger 21,

- at least one compressor 22 positioned between said first and second heat exchangers 20, 21 and arranged to compress said refrigerant fluid between its minimum pressure and its maximum pressure,

- at least one expansion valve 23 which carries out an expansion, at substantially constant enthalpy, and a cooling of the refrigerant fluid.

Said refrigeration circuit 2 can be switched, by means of a switching valve (not shown), e.g. a ?4-way?, between a ?cooling? operating mode and a ?heating? operating mode (and vice versa) with said first and second heat exchangers which can therefore function, if necessary, either as a condenser or as an evaporator.

When in "heating" mode, the refrigerant fluid dissipates heat, condensing, in the second exchanger 21 which therefore acts as a condenser, while it absorbs heat, evaporating, in the first exchanger 20 which acts as an evaporator.

On the contrary, in the "cooling" mode, the first heat exchanger 20 acts as a condenser of the refrigeration circuit 2, the second exchanger 21 as a relative evaporator.

More generally, the second heat exchanger 21 is preferably the one in which the heat exchange takes place between the refrigerant fluid of the refrigeration circuit 2 and the technical fluid of the air conditioning circuit 3.

For clarity of explanation, said second heat exchanger 21 will be referred to as the "main heat exchanger" or, more simply, the "main exchanger".

If necessary, the main heat exchanger 21 can then operate:

- from an evaporator and in this case the refrigerant fluid absorbs, at substantially constant pressure, thermal energy from the technical fluid, cooling it, or

- from a condenser and in this case the refrigerant fluid releases, at substantially constant pressure, part of its thermal energy to the technical fluid, heating it.

Of said main heat exchanger 21, it is therefore possible to identify a primary side 24, in correspondence with which the refrigerant fluid circulates and operates, and a secondary side 25, in correspondence with which the technical fluid of the air conditioning circuit 3 circulates and operates.

As anticipated, the conditioning circuit 3 may comprise at least one circulation pump 30 for the technical fluid and one or more terminals 31 for heating/cooling the environment and/or for sanitary water.

Said terminals 31 can therefore operate:

- from heat dissipation devices and/or from air conditioning units in heating/cooling mode, in this case including, for example, one or more radiators, floor or wall radiant panels, fan coils, convectors or similar devices, and/or

- from heat accumulators containing the fluid circulating in the air conditioning circuit 3, for example from buffers, and/or

- from heat accumulators, for example from hot water boilers (or similar) in the case of domestic water heating.

Without any limiting intent and considering the operating direction F of the technical fluid as a reference, the circulation pump 30 can be placed upstream of the secondary side 25 of the main heat exchanger 21 (see fig. 1).

As stated several times, the heat pump system 1 of the invention is preferably designed to operate with low environmental impact refrigerant fluids (e.g., the well-known R32, propane R290 or similar) which, as seen, however have the disadvantage of being flammable when in contact with particularly hot components or elements or potentially capable of producing sparks.

Also for this reason, the conditioning circuit 3 may further comprise at least one relief valve 43 capable of opening for pressures of the technical fluid greater than, generally, 3 bar, allowing its discharge, for example, into the atmosphere; this condition may occur in the presence of significant refrigerant losses from the refrigeration circuit 2.

Furthermore, a possible ventilation valve 44 (also known as a "joker" or "deaeration" valve), whether manual or automatic, allows the expulsion of small refrigerant leaks coming from the refrigeration circuit 2 as well as any air present in the pipes and/or terminals 31 of said air conditioning circuit 3.

According to a possible embodiment of the invention and without any limiting intent, said relief valve 43 and/or said ventilation valve 44 may be part of a degasser device 4, suitably arranged to stop the flow of technical fluid and/or prevent any leaks of refrigerant fluid, mainly deriving from defects and/or breakages of one or more components or pipes of the refrigeration circuit 2 (e.g., of the main heat exchanger 21), from reaching the heating circuit 3, the related terminals 31 and therefore spreading into the domestic (or commercial/industrial) environment, with harmful and dangerous effects for users.

It is not necessary to dwell too much on the description of the technical and functional characteristics of said degasser device 4 since it is a component already known in itself to a technician in the field, widely used and available in a wide variety of models and construction shapes.

Here it is therefore sufficient to specify how, considering once again the operating direction F of the technical fluid as a reference, said degasser device 4 is placed in the conditioning circuit 3 preferably downstream of the secondary side 25 of the main heat exchanger 21.

Said degasser device 4 may therefore comprise:

- an inlet 40 connected to said secondary side 25 of the main heat exchanger 21,

- an outlet 41 connected to the delivery pipe 32 for the terminals 31 of the air conditioning circuit 3,

- an expansion chamber 42 in which the refrigerant leaks are intercepted and/or separated from the technical fluid through its sudden slowing down and the possible use of separation means such as mesh filters, perforated screens, turbulators or similar (not shown), said expansion chamber 42 being in fluid communication with: - said inlet 40 and outlet 41,

- said at least one relief valve 43 and/or ventilation valve 44 suitable, as seen, to discharge to the outside at least said refrigerant fluid leaks intercepted and/or separated from the technical fluid.

Without any limiting intent, said degassing device 4 may also be of the type comprising a shutter body (not explicitly shown), internal to the expansion chamber 42, e.g. a "floating" shutter, capable, in known ways, of:

- open, or keep open, outlet 41 in conditions of regular operation of the heat pump system 1, thus allowing the normal flow and passage of the technical fluid from the main heat exchanger 21 to the terminals 31 of the air conditioning circuit 3, - close outlet 41 in the event of refrigerant leaks, in particular for quantities exceeding a predefined threshold considered tolerable or non-dangerous, allowing their separation from the technical fluid and preventing them from reaching said terminals 31 and spreading into the domestic (or commercial/industrial) environment.

According to the invention, it is also intended to prevent any possible refrigerant leaks from reaching the terminals 31 of the air conditioning circuit 3 through ?routes? other than those prevented by the operation of the degasser device 4.

More precisely, the aim is to prevent the flow of refrigerant leaks (hereinafter also referred to as "retrograde flow or reflux FR"; see fig. 2a-2b) in the opposite direction to that of the technical fluid's operation, i.e. towards the circulation pump 30 and the return branch 33 of the air conditioning circuit 3 itself.

This can be achieved without the need to include the well-known check valves in the air conditioning circuit 3, normally used to close in the presence of "parasitic circulations CP" of the technical fluid of the heat pump system 1 (i.e. in contrast with the direction given to the fluid by the circulation pump 30; see, for clarity, the arrow CP in fig.

1 and/or 2a-2b).

In other words, according to the invention, the aforementioned check valve is replaced by a safety valve 5, shown schematically in the attached figures, and capable of:

- to ?allow? the technical fluid (e.g. technical water) to pass through it both when circulating in the operating direction F and in the opposite direction, i.e. in the case, as seen, of parasitic circulations CP (which are therefore deliberately tolerated), but

- to close in the event of retrograde flows FR of any refrigerant leaks coming from the main heat exchanger 21, thus blocking its diffusion towards the return branch 33 of the air conditioning circuit 3 and the related terminals 31.

As shown by way of example in fig.1, said safety valve 5 can preferably be positioned, considering the operating direction F of the technical fluid in the conditioning circuit 3, upstream of the secondary side 25 of the main heat exchanger 21.

Preferably, said safety valve 5 can be placed between the outlet of the circulation pump 30 of said air conditioning circuit 3 and the inlet of said secondary side 25 of the main heat exchanger 21.

According to a possible embodiment, which is among the preferred ones, said safety valve 5 may comprise:

- a container body 50 (e.g. cylindrical or box-shaped) equipped with at least a first 51 and second 52 opening for at least the passage of the technical fluid of the air conditioning circuit 3, said openings 51, 52 may consist of holes, slots or similar, and

- at least one shutter 53 capable of moving, substantially vertically, inside the container body 50 and acting as a "plug" for at least one of said passage openings 51, 52.

According to the example of fig. 1, the first opening 51 of said container body 50 of the safety valve 5 is in fluid communication with the delivery of the circulation pump 30, while the second opening 52 is connected, for example via sections of piping, to the inlet of the secondary side 25 of the main heat exchanger 21.

Without any limiting intent, in accordance with a possible embodiment of the invention, said first and second openings 51, 52 may be two opposite passage openings, a lower one 51 and an upper one 52, or located, respectively, on the bottom 55 of the container body 50 of the safety valve 5 and on its relative upper wall 56.

Preferably, the shutter 53 is capable of closing the lower opening 51 of the safety valve 5 exclusively in the case of retrograde refrigerant flows FR, leaving it open in the case of passage of the technical fluid, both in the operating direction F and in the opposite direction of the parasitic circulations CP.

In other words, as will be seen in detail later, the safety valve 5 acts as a stop valve for the refrigerant fluid directed, in the event of leaks, towards the return branch 33 of the air conditioning circuit 3 and the relative terminals 31, but not for the technical fluid which is therefore free to pass through it.

For this purpose, the shutter 53 of the safety valve 5 can comprise a floating body having a lower density than that of the technical fluid; in this way, when there is technical fluid present in the safety valve 5, the shutter 53 floats inside the relative container body 50, leaving open (or opening) its lower opening 51.

The safety valve 5 may also comprise at least one limit switch or stroke limit device 54 (hereinafter simply referred to as the "limit switch 54") which allows the shutter 53 to float in the technical fluid without ever obstructing the upper opening 52, while at the same time ensuring large passage sections and consequent low pressure drops.

Without any limiting intent, said limit switch 54 may for example comprise a suitably sized plate 54 housed inside the container body 50 of the safety valve 5 and capable of acting as an upper blocking element for the floating of the shutter 53.

Naturally, nothing prevents the possibility of foreseeing alternative and/or equivalent systems (variants not shown).

For example, it is possible to shape and size the shutter 53 appropriately to always remain sufficiently distanced from the upper opening 52 of the safety valve 5 and, at the same time, allow the flow of at least the technical fluid. For example, at least two projections could be provided projecting from the upper face of the shutter 53 suitable for acting as abutment elements on the upper wall 56 of the container body 50 of the safety valve 5 and defining radial passages between them for at least said technical fluid.

Alternatively, it is possible to create the aforementioned upper opening 52 on one side of the container body 50 of the safety valve 5, rather than in its upper wall 56, as seen so far.

The density of said shutter 53 is instead greater than that of the refrigerant fluid.

Therefore, when, as a result of the above-mentioned leaks, the safety valve 5 is completely full of refrigerant, which has progressively replaced and substituted the technical fluid, the shutter 53 is no longer able to float, and, thanks also to the contribution of its weight, automatically and spontaneously moves to the bottom 55 of the container body 50, occluding the lower opening 51.

In this way, as anticipated, any possible retrograde flow FR of the refrigerant fluid is stopped, preventing its unwanted and dangerous diffusion towards the air conditioning circuit 3, in particular towards the return branch 33.

For further clarity, the operation of said safety valve 5 of the heat pump system 1 of the invention is described below.

When the heat pump system 1 of the invention operates in standard and/or optimal conditions (i.e. in the absence of leaks and/or malfunctions), the safety valve 5 is affected by the operating flow F of the technical fluid, which passes through it undisturbed and with negligible pressure losses; in fact, the internal volume of the container body 50 and the dimensions and shape of the relative shutter 53, appropriately chosen, offer a resistance to the flow of the technical fluid that is substantially negligible, in any case significantly lower than that of a non-return valve or similar devices.

In such conditions, the shutter 53 of the safety valve 5 is floating and raised from the bottom 55 of the container body 50; that is, it is substantially close to its end-of-travel position, for example in contact with the end-of-travel device 54, thus leaving both the lower 51 and upper 52 passage openings open and free.

In the event of malfunction or breakage of one or more components of the refrigeration circuit 2 (e.g. the main heat exchanger 21), a significant quantity of refrigerant, characterised by higher pressures than those of the technical fluid, could penetrate and enter the air conditioning circuit 3 and reach, with retrograde flow FR, the safety valve 5.

At this point, the high pressure refrigerant leaks begin to "press" and "push" the technical fluid out of the container body 50 through the lower opening 51 of the safety valve 5 which remains substantially open thanks to the buoyancy of the shutter 53 provided by the residual technical fluid.

However, due to the progressive emptying of said technical fluid, replaced by the refrigerant fluid, the floating shutter 53 will begin to move internally within the container body 50, moving away from the aforementioned end-of-travel position (i.e. from the end-of-travel device 54) and approaching the lower opening 51 of the safety valve 5.

When all the technical fluid has been completely expelled from the container body 50 of the safety valve 5 and totally replaced by the refrigerant, the shutter 53, no longer able to float, will rest on the bottom 55 of the container body 50 itself, hermetically closing, due to the high pressures of the refrigerant itself, the passage 51 towards the conditioning circuit 3.

It is therefore evident that the safety valve 5 of the heat pump system 1 of the invention does not prevent, in any way, any parasitic circulations CP of the technical fluid (as instead happens with traditional non-return valves), stopping, in fact, only retrograde flows FR of the refrigerant in the event of leaks and escapes from the refrigeration circuit 2.

In other words, said safety valve 5 is inserted in the heat pump system 1 of the invention with the sole intent of stopping any retrograde flows FR of refrigerant towards the air conditioning circuit 3, without any interest or purpose of also blocking any parasitic circulations CP of the technical fluid (e.g. technical water), which are therefore substantially tolerated.

The use of a safety valve 5, as described, can also lead to a second order of advantages and to an increased efficiency and operating life of the heat pump system 1 of the invention.

It has in fact been said several times that the refrigerant fluid operates at high pressures (even in the order of a few dozen bars) and how, in the event of leaks, it can generate pressure peaks which, propagating along the air conditioning circuit 3, could cause damage to the relevant pipes and/or components, generally tested to work at lower pressures (usually equal to 3 bars).

The container body 50, acting as an expansion volume for the refrigerant, additional to that normally provided by the air conditioning circuit 3, therefore allows said pressure peaks to be lowered and compensated more quickly, reducing potential damage to components such as the main heat exchanger 21, the degasser device 4 (in particular, its joints or fittings for connection to the pipes of the air conditioning circuit 3), the circulation pump 30, etc.

Finally, it should be noted that numerous variations of the heat pump system of the invention are possible for those skilled in the art, without thereby departing from the areas of novelty inherent in the inventive idea, just as it is clear that in the practical implementation of the invention the various components described above may be replaced by technically equivalent elements.

For example, as an alternative to what has been said up to now, nothing prevents the said relief valves 43 and/or ventilation valves 44 of the air conditioning circuit 3, rather than being part of the degasser device 4, from being directly integrated into the safety valve 5 of the invention, for example installed and in fluid communication with its container body 50.

? it is also possible to foresee that said relief valves 43 and/or ventilation valves 44 can be simultaneously provided both in the degasser device 4 and in the safety valve 5, so as to guarantee increased safety and efficiency of the heat pump system 1 of the invention.

In conclusion, it appears evident that with the safety valve 5 of the heat pump system 1 of the invention the intended purposes are achieved, in particular the possibility of eliminating, or in any case effectively limiting, the risk that any refrigerant leaks, spreading through the air conditioning circuit 3, may reach the installation and/or use environment of said heat pump system 1, endangering, in the event of the formation of flammable and/or explosive concentrations, the safety of the users and/or the integrity of the related building structures.

Furthermore, the safety valve 5 of the invention offers, as seen, a substantially negligible resistance to the flow of the technical fluid of the air conditioning circuit 3 and, therefore, pressure losses that are significantly lower than those typical of a non-return valve or similar devices.

Claims (1)

Rev 1. Heat pump system (1) comprising at least: - a refrigeration circuit (2) in which a refrigerant fluid circulates and operates at the primary side (24) of a main heat exchanger (21), - an air conditioning circuit (3) in which a technical fluid, used for room heating/cooling functions and/or for the production of sanitary water, circulates and operates in correspondence with the secondary side (25) of the same main heat exchanger (21), in which: - in said main heat exchanger (21) the heat exchange between said refrigerant fluid and technical fluid takes place, - said conditioning circuit (3) comprises at least one circulation pump (30) for said technical fluid and one or more terminals (31) for heating/cooling the environment and/or for the production of sanitary water, characterised in that said conditioning circuit (3) further comprises a safety valve (5) capable of: - allowing said technical fluid to pass through it both when circulating in the operating direction (F) and in the event of its parasitic circulations (CP) in said conditioning circuit (3), - close in the event of refrigerant fluid leaks in said air conditioning circuit (3) in the opposite direction (FR) to the operating direction (F) of said technical fluid, said safety valve (5) therefore acting as a stop valve for said refrigerant fluid but not for said technical fluid. Riv 2. Heat pump system (1) according to claim 1 characterised in that said safety valve (5) is located, with reference to the operating direction (F) of said technical fluid, upstream of said secondary side (25) of said main heat exchanger (21; 20). Riv 3. Heat pump system (1) according to claim 2 characterised in that said safety valve (5) is located between the outlet of said circulation pump (30), located upstream of said main heat exchanger (21), and the inlet of said secondary side (25) of said main heat exchanger (21). Riv 4. Heat pump system (1) according to one or more of the preceding claims characterised in that said safety valve (5) comprises at least: - a container body (50) equipped with at least a first (51) and second (52) passage opening for at least said technical fluid of the air conditioning circuit (3), and - at least one shutter (53) capable of moving internally within the container body (50) to act as a "plug" for at least one of said passage openings (51, 52). Riv 5. Heat pump system (1) according to the previous claim characterised in that said shutter (53) is a floating body (53) having a density lower than that of said technical fluid but higher than that of said refrigerant fluid, said shutter (53) being capable of: - float inside said container body (50) of said safety valve (5) in the presence of technical fluid, in which case said first (51) and second opening (52) are both always open, - occlude said first opening (51) of said container body (50) of said safety valve (5) when completely full of said possible refrigerant leaks, said shutter (53) blocking and/or stopping the diffusion of said refrigerant in/towards the return branch (33) of said air conditioning circuit (3). Riv 6. Heat pump system (1) according to claim 5 characterised in that said safety valve (5) internally comprises a limit switch device (54) for said floating shutter (53), said limit switch device (54) allowing said shutter (53) to float in the container body (50) of said safety valve (5) without ever obstructing its second opening (52). Riv 7. Heat pump system (1) according to one or more preceding claims characterised in that said first (51) and second (52) openings are two opposite passage openings, a lower one (51) and an upper one (52), located, respectively, on the bottom (55) of the container body (50) of said safety valve (5) and on its relative top wall (56). Riv 8. Heat pump system (1) according to one or more of the preceding claims characterised in that said container body (50) of said safety valve (5) also acts as a supplementary expansion volume for said possible refrigerant leaks. Riv 9. Heat pump system (1) according to one or more of the preceding claims characterised in that said conditioning circuit (3) further comprises a relief valve (43). Riv 10. Heat pump system (1) according to one or more of the preceding claims characterised in that said conditioning circuit (3) further comprises a ventilation valve (44). Riv 11. Heat pump system (1) according to claim 8 and/or 9 characterised in that said relief valve (43) and/or said ventilation valve (44) are integrated with said safety valve (5) and in fluid communication with its container body (50). Riv 12. Heat pump system (1) according to claim 8 and/or 9 characterised in that said relief valve (43) and/or said ventilation valve (44) are part of a degasser device (4) of said air conditioning circuit (3). Riv 13. Heat pump system (1) according to claim 8 characterised in that said degasser device (4) is located, with reference to the operating direction (F) of said technical fluid, downstream of said secondary side (25) of the main heat exchanger (21), Riv 14. Heat pump system (1) according to the previous claim characterised in that said degasser device (4) further comprises at least: an inlet (40) connected to said secondary side (25) of said main exchanger (21), an outlet (41) connected to a delivery pipe (32) of said terminals (31) of the air conditioning circuit (3), an expansion chamber (42) in which said refrigerant leaks are intercepted and/or separated from said technical fluid. Riv 15. Heat pump system (1) according to one or more of claims 12 to 14 characterised in that said degasser device (4) is of the "float" type. Riv 16. Heat pump system (1) according to any preceding claim characterised in that said refrigerant fluid of the refrigeration circuit (2) is a low environmental impact refrigerant, for example propane R290, difluoromethane R32 or similar/similar.