FR2916033A1 - Cold water and hot water mixing system for e.g. hotel, has rod and actuator simultaneously and respectively opening and closing of valve systems in controlled manner during disinfection phase against legionella bacteria - Google Patents

Abstract

The system has a by-pass channel (16) provided with a valve system (19), normally closed, for interception of a by-pass flow of hot water between a hot water flow entry conduit (12) and a mixed water sending conduit (15), and a valve system (22) normally closed, for interception of a by-pass flow of cold water in a cold water entry conduit (13). A connecting rod (25) and a control actuator (26) are actively connected to the valve systems and simultaneously and respectively opening and closing of the valve systems in a controlled manner during disinfection phase against legionella bacteria.

Description

DESCRIPTION

  BACKGROUND OF THE INVENTION The present invention relates to a system and a group for the mixing of cold water and hot water for sanitary installations, with the disinfection function against legionella bacteria, in which in particular a mixer is provided. thermostatic type of anti-scalding, for the distribution of domestic hot water at a fixed temperature.

  CURRENT SITUATION In the context of sanitary installations, in particular installations for hotels, communities, hospital structures and the like, the use of thermostatic blast burners is known.

  In accordance with current safety regulations, these are intended to allow the distribution of domestic hot water at a set temperature, below a safety value, to prevent users from getting burned. These thermostatic burn-in mixers are generally installed in branch boxes, in which the mixer is connected to a first inlet conduit for a flow of hot water from the boiler, and to a branch of a second conduit. input for a flow of cold water that extends into the output for the user supply; in addition, at the output of the mixer is provided a third delivery duct or discharge for the distribution of mixed water at the set temperature. The recent standards for disinfection of the sanitary facilities against legionella bacteria, which provide, among other things, that the water taps connected to the mixed water supply duct may be thermally disinfected with hot water at high temperature, have involved the need to adopt a bypass channel or bypass between the first inlet conduit for hot water and the third delivery conduit for the mixed water, so as to possibly allow the Direct passage of water at high temperature to the same taps without passing through the thermostatic mixer. 1 The bypass channel has a normally closed valve system for intercepting the hot water derived flow, which can be controlled by electricity, with a special actuator, or manually to be periodically brought into an open position to to disinfect the Legionella bacteria. A similar mixing system, however, has the disadvantage that when the disinfection against legionella bacteria is carried out, in the mixed water supply duct confluent simultaneously both the stream of hot water coming from the bypass channel, the mixed water flow from the mixer, with the consequence that the disinfection is less effective because of the decrease in the temperature of the water in the duct, induced by the presence of the mixed water. This mixing system also has additional disadvantages related to the presence of various elements to be connected to each other, which have on one side a great complexity of installation and on the other a large size of the system itself.

  OBJECTS OF THE INVENTION The main object of the present invention is to provide a system and a mixing group for sanitary installations which allow effective disinfection against the legionella bacterium of the plant, thanks to a high temperature of the plant. hot water flowing in the duct sending water to the faucets. Another object of the present invention is to provide a system and a mixing unit for sanitary installations, in which the disinfection function against legionella bacteria is manageable in a simple and error-free way by the user. A further object of the present invention is to provide a mixer group for sanitary installations which has a compact construction of limited dimensions and which can be installed quickly and easily, while at the same time minimizing installation costs. BRIEF DESCRIPTION OF THE INVENTION The described objectives can be achieved with a system allowing the mixing of cold water and hot water for sanitary installations, fulfilling the function of disinfection against legionella bacteria, comprising: a first conduit inlet for a flow of hot water; a second inlet duct for a flow of cold water; a thermostatic mixer having a mixing chamber in which said first and second water inlet ducts open; a third conduit for sending mixed water to the outlet of said mixing chamber; and - a bypass channel between said first inlet conduit for hot water and said third supply conduit for the mixed water, said bypass channel comprising a first normally closed valve interception system. a flow derived from hot water between said first and said third conduit, characterized by comprising a second normally open valve system for intercepting the flow of cold water in said second inlet conduit, and comprising control means connected to said first and second valve systems, said control means being shaped and arranged to simultaneously control, in a controlled manner, in opening, respectively closing said first and second valve systems during a disinfection phase against legionella bacteria. The above can also be obtained with a mixer group for sanitary installations, fulfilling the function of disinfection against legionella bacteria, characterized by comprising a hollow body having: a first inlet duct for a flow of hot water ; a second inlet duct for a flow of cold water; a mixing chamber into which said first and second water inlet ducts open; a third conduit for sending mixed water to the outlet of said mixing chamber; and a bypass channel for a flow of hot water between said first inlet conduit for hot water and said third supply conduit for the mixed water, the mixer unit further comprising: a device thermostatic mixing hot water and cold water having a thermostatic wax actuator that if found in said mixing chamber, - a first valve system, normally closed, in said bypass channel, said first valve system comprising a first sealed seat for a first movable shutter for intercepting the hot water derived stream, and - a second normally open valve system in said second inlet conduit, said second valve system comprising a second sealed seat for a second movable shutter for intercepting the flow of cold water, and by including a connection rod between said first and said second interception shutter, the rod being on it is connected to a control actuator shaped and arranged to simultaneously control, in a controlled manner, in opening, respectively closing said first and second interception valves, during a phase of disinfection against the legionella bacteria.

  BRIEF DESCRIPTION OF THE FIGURES These and other features according to the present invention will become clearer in the following description with reference to the accompanying figures, in which: - Figure 1 shows a longitudinal section of a mixing group under a first embodiment of the invention, with the valve systems in the mixing position; FIG. 2 represents a section of the group of FIG. 1, with the valve systems in position of disinfection against the legionella bacterium; FIG. 3 represents a perspective of the group of FIG. 1; - Figure 4 is a sectional view of the group of Figure 1, along the line 4-4; FIGS. 5 and 6 are a schematic representation of a mixing system according to a second embodiment of the invention, with the valve systems in the mixing position, respectively in the disinfection position against the legionella bacterium; and FIGS. 7 and 8 are a diagrammatic representation of a mixing system according to a third embodiment of the invention, with the valve systems in the mixing position, respectively in the disinfection position against the legionella bacteria. .

  DETAILED DESCRIPTION OF THE INVENTION The general features of the present invention will be illustrated hereinafter through some exemplary embodiments. A first preferred embodiment of the present invention is illustrated in Figures 1 to 4, in which there is shown a mixing unit for the mixing of cold water and hot water in sanitary installations, performing the function of disinfection against legionella bacteria. The group, indicated generally by reference numeral 10, comprises a hollow body 11, preferably made of a single piece by melting, which in turn comprises a first inlet duct 12 for a stream of hot water, and a second inlet conduit 13 for a stream of cold water which open into a mixing chamber 14 from which a third delivery conduit 15 for the mixed water.

  The hollow body 11 further comprises a bypass channel 16 for a flow of hot water between the first inlet conduit 12 for the hot water and the third supply conduit 15 for the mixed water. Group 10 also comprises a thermostatic mixing device 17 for mixing hot water and cold water, having a thermosetatic wax actuator 18 which extends into the mixing chamber 14. In the branch channel 16 is provided a valve system 19, normally closed, which comprises a first sealed seat 20 for a first movable shutter 21 for intercepting the stream of hot water. In the second inlet conduit 13 for cold water is instead provided a second valve system 22, normally open, which comprises a second sealed seat 23 for a second movable shutter 24 for intercepting the flow of cold water. In addition, the group 10 comprises a connecting rod 25 between the first and the second interception shutter 21, 24, which is also connected to a control actuator 26 shaped and arranged to simultaneously control, in a controlled manner, in opening respectively closing the first and the second interception shutter 21, 24, during a phase of disinfection against the legionella bacterium. The mixing chamber 14 extends on a longitudinal axis, between a first axial end, in which is provided an insertion opening 14 'for the thermostatic mixing device 17, and a second end opposite to the first, of which coaxially the delivery conduit 15. The mixing chamber 14 has a first passage opening 27 connected to the first inlet conduit 12, and a second passage opening 28 connected to the second inlet conduit 13, these openings are arranged axially and spaced apart from each other along the mixing chamber 14. The thermostatic mixing device 17 comprises a tubular shutter 29 which is actively connected to the thermostatic wax actuator 18, so as to be axially movable in the mixing chamber 14 between a first position back and a second position in front of closing the first, respectively the second opening 27, 28 of passage of the 'water.

  Preferably, the first inlet duct 12 for hot water comprises a first connection piece 30 to a hot water supply pipe from a heat source (not shown), which extends transversely through relative to the axis of the mixing chamber 14 on a first side of the hollow body 11; from this first nozzle 30 extends a first section of conduit 12 'which extends parallel to the axis of the mixing chamber 14 on the first side of the hollow body. The first duct 12 also comprises a second duct section 12 ", seen in FIGS. 3 and 4, extending from the first section 12 'transversely to the axis of the mixing chamber 14, on a next to the same mixing chamber 14, from this second section 12 "extends a third section of conduit 12" 'which opens into the mixing chamber 14 through the first passage opening 27. The third section 12 "'in particular extends substantially parallel to the axis of the mixing chamber 14 on a second side of the hollow body 11 opposite the first side, having an intermediate piece forming a connection between the second section 12" of conduit, which is offset from the mixing chamber 14, and the first passage opening 27. Preferably, the second inlet conduit 13 for cold water comprises a second nozzle 31 for connecting to a piping adduction cold water (not ésentée), which extends transversely to the axis of the mixing chamber 14 on the first side of the hollow body 11; from this second connection 31, extends a longitudinal section of conduit 13 'which extends parallel to the axis of the mixing chamber 14 on the first side of the hollow body 11 to open into the mixing chamber 14 through the second passage opening 28. Between the longitudinal section 13 'of the second conduit 13 and the second connector 31 is provided a hole or narrow communication passage 32 placed on the first side of the hollow body 11; in addition, still on the first side of the hollow body 11, the same longitudinal section 13 'is axially distant from the first section 12' of the first duct 12. As has been said, the third delivery duct 15 is extends coaxially from the second axial end of the mixing chamber 13, and ends with a third connection end 33 to a mixed water distribution pipe, which is not shown.

  In particular, the third delivery duct 15, at the height of the second axial end of the mixing chamber 14, comprises an initial section 15 'which is interposed between the third section 12 "' of the first inlet duct 12 and the longitudinal section 13 'of a second inlet duct 13.

  The bypass channel 16 extends between the lateral hole 34 of the third section 121 "of the first inlet duct 12, and an intermediate point of the third delivery duct 15, preferably on the section plane of FIG. , the third delivery duct 15 and the bypass duct 16 have a Y-shaped section, in which the Y-shaft is represented by the third connecting end-piece 33. In particular, the lateral hole 34 of the third section 121 "is disposed on the second side of the hollow body 11 in a position of axial alignment with the communication hole 32 of the second inlet duct 13, along an axis orthogonal to the longitudinal axis of the mixing chamber 14.

  The first sealed seat 20 of the first valve system 19 is of annular type and is disposed on a peripheral edge of the lateral hole 34 of the first inlet duct 12, preferably on the side facing the bypass channel 16; the second sealed seat 23 of the second valve system 22, still of annular type, is instead disposed inside the second connection piece 31 on a peripheral edge of the communication hole 32 between the connection 31 itself and the longitudinal section 13 of the second inlet duct 13. In particular, the first and second sealed seats 20, 23 are arranged at a first mutual distance in the direction of the orthogonal alignment axis between the lateral hole 34 and the communication hole 32 .

  The connecting rod 25 extends through the lateral hole 34 of the first inlet conduit 12 and the communication hole 32 of the second inlet conduit 13; in this case, the first and the second shutters 21, 24 are connected to the rod 25 in axial positions spaced apart in the direction of the orthogonal axis, preferably at a mutual distance greater than the first distance between the sealed seats. 20, 23, with the first shutter 21 disposed in the bypass channel 16, and the second shutter 24 disposed in the second connection nozzle 31. In any case, a different arrangement of the shutters and their sealed seats is not excluded, providing for example that the first shutter 21 and its sealed seat are in the third section 12 "'of the first inlet duct 12, and that the second shutter and its sealed seat are in the longitudinal section 13' of the second duct 12 13. The connecting rod 25 has a first end 25 'which extends through a side opening 35 of the bypass channel 16 disposed on the second side of the body. s hollow 11 for the attachment of the control actuator 26; the end 25 'of the rod 25 is thus actively connected to the control actuator 26, and resilient thrust means 36 shaped and arranged to act in combination with the same control actuator 26, these are for example in the form of a spring 36 disposed coaxially with the rod 25 to act on a plate connected to the rod itself. The control actuator 26 may for example be of the electric type and preferably of the electronic type; in the latter case, as illustrated with dashed lines in FIGS. 1 and 2, the actuator 26 comprises an axially expandable thermostatic actuator 37, of the wax type, actuated by an electric heating resistor 38, and a retaining spring 39 acting in opposition to the actuator 37 to exert an axial thrust on the rod 25 tending to close the first valve system 19 and to open the second valve system 22.

  In this way, when the actuator 37 is engaged by the resistor 38 during the phase of disinfection against the legionella bacterium, the rod 25 is released by the axial thrust of the spring 39, thus allowing the spring 36 to exert an opposite axial thrust tending to open the first valve system 19 and to close the second valve system 22.

  The group 10 preferably comprises a transverse sleeve 40 for passage for the connecting rod 25 in the initial section 15 'of the delivery conduit 15, the sleeve is sealingly inserted in through holes 41,42 provided in the side walls. in the same initial section 15 'of the third section 12 "' of the first inlet duct 12, respectively of the longitudinal section 13 'of the second inlet duct 13. In particular, the through holes 41, 42 are aligned with the orthogonal alignment axis between the lateral hole 34 of the first inlet duct 12 and the communication hole 32 of the second inlet duct 13, and the connecting rod 25 is inserted sealingly and slidably into the passage sleeve 40, a similar solution allows to achieve in a simple way the operational connection between the shutters 21, 24, allows simultaneously to maintain the compact dimensions of the hollow body 11, and to prevent leakage water between the initial section 15 'of the delivery duct 15, the third section 12 "' of the first inlet duct 12, and the longitudinal section 13 'of the second inlet duct 13. The group 10 comprises control means 43 of the control actuator 26, connected to a power supply source, which is not shown; for example, these control means 43 may be in the form of an electrical switch 44 and / or a timer 45 provided to activate the control actuator 26 in a delayed manner, or an electronic control unit provided for to activate in a controlled manner the control actuator 26. Alternatively, the disinfection function against the bacterium legionel-35a can be performed manually, and therefore in this case, the control actuator 26 will be in the form of a joystick manual control. It is evident from the above that the mixing unit according to the present invention performs a first function against burns, which represents the normal operating condition of the group, and a second function of periodic disinfection against the legionella bacteria of the installation . In particular, with regard to the mixing position illustrated in FIG. 1, in which the shutter for intercepting the flow in the channel of separation is closed and the shutter for intercepting the flow of cold water in entrance is open, the group performs the function of preventing burns, providing the outlet of mixed water at a programmed temperature. On the other hand, with regard to the disinfection position illustrated in FIG. 2, where the shutter of interception of the flow in the channel of departure has been put in the open position by the control actuator and the shutter for intercepting the inlet cold water flow has been carried in the closed position by the same actuator, the group makes it possible to fulfill the disinfection function of the installation against the legionella bacterium, obtaining a particular effectiveness of said disinfection , because during this operation the cold water is kept closed and therefore the hot water flowing in the conduit for sending water to the faucets has a high temperature. In addition, the group has a compact construction of limited cost and easy to install, compared to currently used systems.

  More generally, the present invention can be configured as a system for the mixing of cold water and hot water for sanitary installations, performing the function of disinfection against legionella bacteria. In particular, with respect to the embodiment illustrated in FIGS. 5 and 6, and the subsequent embodiment of FIGS. 7 and 8, where the same reference numerals have been used to indicate like or equivalent parts with respect to 1 to 4, the system comprises a first inlet duct 12 for a hot water stream (represented by a thick continuous line), and a second inlet duct 13 for a flow of water. cold water (represented by a continuous line of average thickness between the thick line of hot water and the thin line used to indicate the ducts), which open into the mixing chamber of a thermostatic mixer 17. The system further comprises a third delivery conduit 15 for the mixed water (represented by a thick dashed line) at the outlet of the mixing chamber, and a bypass channel 16 between the first inlet conduit 12 for the water hot and the third delivery duct 15 for the mixed water; the bypass channel 16 in turn comprises the first normally closed valve system 19 for intercepting a flow of hot water between the first and third conduits 12, 15. The second conduit 13 for the water cold on the contrary comprises the second valve system 22, normally open, intercepting the flow of water. The system according to the present invention finally comprises control means actively connected to the first and second valve systems 19, 22, for simultaneously controlling, in a controlled manner, in opening, respectively closing the first and the second valve system 19, 22, during a phase of disinfection against legionella bacteria.

  In particular, as illustrated in FIGS. 5 and 6, the control means may comprise a single electric control actuator 47, preferably of the electrothermal type, actively connected to the first and second valve systems 19, 22, for example by means of a rod or mechanical part 48 of junction, so as to simultaneously control, in a controlled manner, the valve systems themselves, through adequate control means 44 of the actuator connected to a power source ( who is not represented). Alternatively, as can be seen in FIGS. 7 and 8, the control means may comprise a first and a second electric control actuator 49, 50, respectively connected to the first and second valve systems 19, 22, whose actuators are actively connected to the control means, in turn connected to a power source and provided for controlled and simultaneous actuation of said actuators.

  The control means 44 may in particular comprise an electric switch 45 and / or a timer 46 provided for activating the control actuators 47, 49, 50 in a delayed manner, or an electronic control unit provided for activating in a controlled manner. controlled said control actuators. In a manner analogous to what has been said for the mixing group, to which reference is made, the mixing system according to the present invention comprises a first function against burns, illustrated in FIGS. 5 and 7 for both forms of realization of the above system, and a second function of periodic disinfection against the legionella bacteria of the installation, illustrated on the contrary in Figures 6 and 8 for the two embodiments of the system. What has been said and shown in the accompanying figures has been given by way of example and illustration of the general features of the invention, and some of its preferred embodiments; therefore modifications and variations of the system and the mixing unit for sanitary installations are possible, without departing from the subject of the claims.

Claims (27)

claims   1. System for the mixing of cold water and hot water for sanitary installations, performing the function of disinfection against legionella bacteria, comprising: - a first inlet duct (12) for a flow of hot water; a second inlet duct (13) for a flow of cold water; a thermostatic mixer (17) having a mixing chamber (14) into which said first and second water inlet ducts (12, 13) open; a third conduit (15) for sending or discharging mixed water at the outlet of said mixing chamber (14); and - a bypass channel (16) between said first inlet conduit (12) for hot water and said third delivery conduit (15) for the mixed water, said bypass channel (16) comprising a first Valve system (19), normally closed, for intercepting a flow of hot water between said first and said third ducts (12, 15), characterized by comprising a second valve system (22). ), normally open, interception of the flow of cold water in said second inlet conduit (13), and by comprising control means (25, 26) actively connected to said first and second valve systems ( 19, 22), said control means (25, 26) being shaped and arranged to simultaneously control, in a controlled manner, in opening, respectively closing said first and second valve systems (19, 22), during a disinfection phase against legionella bacteria.   Mixing system according to Claim 1, characterized in that the said control means (25, 26) comprise a single electric control actuator (47) actively connected to the said first and second valve systems (19, 22) for controlling simultaneously, in a controlled manner, the valve systems themselves.   Mixing system according to claim 2, characterized by comprising a mechanical element (48) for functional connection between said control actuator (47) and said first and second valve systems (19, 22).   4. Mixing system according to claim 2 or 3, characterized by comprising control means (44) for said control actuator (47), connected to a power source.   Mixing system according to claim 1, characterized in that said control means comprise a first and a second electric control actuator (49, 50) respectively connected to said first and second valve systems (19, 22), said first and second electric actuators (49, 50) being actively connected to control means (44) provided for controlled and simultaneous actuation of the actuators themselves (49, 50), said control means (44) being connected to a source power supply.   6. mixing system according to claim 4 or 5, characterized in that said control means (44) comprise an electric switch.   7. Mixing system according to any one of claims 4 to 6, characterized in that said control means (44) comprise a timer provided for switching on said control actuators (49, 50) in a time-delayed manner.   8. mixing system according to any one of claims 4 to 7, characterized in that said control means (44) comprise an electronic control unit provided to engage in a controlled manner said control actuators (49, 50).   9. Mixing system according to claim 2 or 5, characterized in that the control actuator (47, 49, 50) is of the electrothermal type.   Mixing unit for sanitary installations, performing the function of disinfection against legionella bacteria, characterized by comprising a hollow body (11) having: - a first inlet duct (12) for a flow of hot water; a second inlet duct (13) for a flow of cold water; a mixing chamber (14) into which said first and said second water inlet ducts (12, 13) open; a third conduit (15) for sending mixed water to the outlet of said mixing chamber (14); and a bypass channel (16) for a stream of hot water flow between said first inlet conduit (12) for hot water and said third delivery conduit (15) for the mixed water, the mixing unit further comprising: - a thermostatic device (17) for mixing hot and cold water, having a thermostatic wax actuator (18) which extends into said mixing chamber (14), a first valve system (19), normally closed, in said bypass channel (16), said first valve system (19) comprising a first sealed seat (20) for a first movable interception shutter (21) (21). ) of the hot water derived stream, and - a second normally open valve system (22) in said second inlet duct (13), said second valve system (22) comprising a second watertight seat (23) for a second moving shutter (24) for intercepting the flow of cold water, and for comprising a connecting rod (25) operable between said first and said second interception shutter (21, 24), the rod (25) being furthermore connected to a control actuator (26) shaped and arranged to simultaneously control, in a controlled manner, in opening, respectively closing said first and second intercepting shutters (21, 24) during a phase of disinfection against the legionella bacterium.   11. mixing unit according to claim 10, wherein said mixing chamber (14) extends along a longitudinal axis, characterized in that said mixing chamber (14) has a first opening (27) passage connected at the first inlet duct (12) of the hot water, and a second passage opening (28) connected to the second inlet duct (13) of the cold water, said first and said second openings (27, 28 ) passing axially disposed spaced apart along said mixing chamber (14).   12. mixing unit according to claim 11, characterized in that said thermostatic mixing device (17) comprises a tubular ob-turateur (29) actively connected to said thermostatic actuator (18) wax, said tubular shutter (29) being movable axially in said mixing chamber (14) between a first position back and a second position in front of closing said first, respectively said second opening (27, 28) for passage of water.   13. mixing unit according to claim 12, characterized in that said first conduit (12) inlet for hot water comprises: - a first connection piece (30) to a piping of hot water supply from a heat source, said first connector (30) extending transversely to the axis of the mixing chamber (14) on a first side of the hollow body (11); - a first duct section (12 ') which extends parallel to the axis of the mixing chamber (14) on said first side of the hollow body (11); a second pipe section (12 ") extending transversely to the axis of the mixing chamber (14) on one side of the mixing chamber itself (14); and - a third section (12") ') of conduit which extends substantially parallel to the axis of the mixing chamber (14) on a second side of the hollow body (11) opposite said first side, said third section (12m) opening in said mixing chamber (14) through said first passage opening (27).   14. mixing unit according to claim 13, characterized in that said second conduit (13) inlet for cold water comprises: - a second nozzle (31) for connection to a piping 20 of cold water supply said second connector extending transversely to the axis of the mixing chamber (14) on said first side of the hollow body (11); and a longitudinal pipe section (13 ') extending parallel to the axis of the mixing chamber (14) on said first side of the hollow body (11), said longitudinal section (13') being provided with a hole (32) communicating with the second nozzle (31) on said first side, the longitudinal section (13 ') opening into said mixing chamber (14) through said second passage opening (28), said longitudinal section (13 ') of the second inlet duct (13) being axially remote from said first section (12') of the first inlet duct (12) for hot water.   A mixing unit according to claim 14, wherein said mixing chamber (14) has at an axial end an opening for entering said thermostatic device (18), characterized by said third conduit (15) being sending extends coaxially from a second axial end of said mixing chamber (14) opposite to said first axial end, the sending conduit (15) terminating in a third end piece (33) connecting to a mixed water distribution pipe, and in that said third pipe (15) for sending, at height of said second axial end of the mixing chamber (14), comprises an initial section (15 '). ) interposed between said third section (12m) of the first inlet duct (12) and said longitudinal section (13 ') of the second inlet duct (13).   16. Mixing unit according to any one of claims 13 to 15, characterized in that said bypass channel (16) extends between a lateral hole (34) in said third section (12m) of the first inlet duct (12) for hot water and said third delivery conduit (15), said side hole (34) being disposed on said second side of the hollow body (11) in a position axially aligned with said communication hole (32) the second inlet duct (13), along an axis orthogonal to said longitudinal axis of the mixing chamber (14).   17. mixing unit according to claim 16, characterized in that said first sealed seat (20) of the first valve system (19) is disposed on a peripheral edge of said lateral hole (34) of the first inlet duct ( 12), on the side facing said bypass channel (16), and in that said second sealed seat (23) of the second valve system (22) is disposed in said second connection piece (31) on one edge peripheral of said communication hole (32) between the same connection and the longitudinal section (13 ') of the second inlet duct (13).   A mixing unit according to claim 17, wherein said first and said second sealed seats (20, 23) are arranged at a first reciprocal distance in the direction of the orthogonal alignment axis between said lateral hole (34) of the first inlet duct (12) and said communication hole (32) of the second inlet duct (13), characterized in that the connecting rod (25) extends through said lateral hole (34) of the first inlet duct (12) and said communication hole (32) of the second inlet duct (13), said first and said second shutter (21, 24) being connected to the same shank (25) in remote positions axi in the direction of said orthogonal axis, a reciprocal distance greater than said first distance between said watertight seats (20,23), the first shutter (21) being disposed in said bypass channel (16), the second shutter (24) being disposed in said second coupling end (31) ent.   Mixing unit according to claim 18, wherein the bypass channel (16) has a junction opening for said control actuator (26) disposed on said second side of the hollow body (11), characterized in that said rod (16) 25) has a first end (25 ') which extends through said junction opening, said first end (25') of the connecting rod (25) being actively connected to said control actuator (26). ), and resilient means (36) thrust shaped and provided to act in combination with said control actuator (26).   20. Blending unit according to any one of claims 16 to 19, characterized by comprising a sleeve (40) passing through said connecting rod (25) in said initial section (15 ') of the duct. sending (15), said passage sleeve (40) being sealingly inserted into passing holes (41,42) provided in the lateral separation walls of the same initial section (15 ') of said third section (12m) of the first duct inlet (12) and said longitudinal section (13 ') of the second inlet duct (13), said passing holes (41, 42) being aligned on said orthogonal alignment axis between said lateral hole (34) the first inlet conduit and said communication hole (32) of the second inlet conduit, the connecting rod (25) being sealingly and slidably inserted into said passage sleeve (40).   21. mixing unit according to any one of claims 10 to 20, characterized in that said control actuator (26) is of the electric type.   22. Mixer group according to claim 21, characterized by comprising control means (44) for said control actuator (26), connected to a power source.   23. mixing unit according to claim 22, characterized in that said control means (44) comprise an electrical switch.   Mixer unit according to claim 22 or 23, characterized in that said control means (44) comprise a timer provided for switching said control actuator in a time-controlled manner.   25. Mixer group according to any one of claims 22 to 24, characterized in that said control means (44) comprise an electronic control unit designed to engage in a controlled manner said control actuator (26).   26. Mixing unit according to any one of claims 21 to 25, characterized in that the control actuator (26) is of the electrothermal type.   27. mixing unit according to any one of claims 10 to 20, characterized in that said control actuator (26) is a manual control lever. 19