EP2683989A1

EP2683989A1 - Unit for distributing fluids

Info

Publication number: EP2683989A1
Application number: EP12718354.9A
Authority: EP
Inventors: Riccardo Ferrero
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-03-07
Filing date: 2012-03-07
Publication date: 2014-01-15
Also published as: CN103370576A; ITTO20110197A1; WO2012120455A1

Abstract

The unit for distributing fluids (10) comprises a main housing (12), internally enclosing: a supply pipe (14) comprising an inflow segment (20) arranged to be connected, at its inlet, with a pressurised sanitary water source, a first distribution segment (22) intended to provide cold sanitary water, and a second distribution segment (24) intended to provide heated sanitary water; a heating circuit (16) arranged to be connected with a source of pressurised heat carrier fluid; and heat exchange means (18) connected to the supply pipe (14) and the heating circuit (16) so as to allow a heat transfer from the heating circuit (16) to the supply pipe (14). The unit (10) further comprises an inner housing (26) made of thermally insulating material and enclosed within the main housing (12). The inner housing (26) internally encloses the heating circuit (16), the heat exchange means (18) and the second distribution segment (24), while leaving outside the first distribution segment (22) and the portion of the inflow segment (20) which is located upstream of the first distribution segment (22).

Description

UNIT FOR DISTRIBUTING FLUIDS

DESCRIPTION

Technical field

The present invention relates to a unit for distributing fluids.

More specifically, the invention relates to a unit for distributing fluids according to the preamble of appended claim 1.

Prior Art

Use of a unit for distributing fluids according to the preamble of appended claim 1 is known in the field.

An example of such a unit for distributing fluids is disclosed in published European Patent Application no. EP 1 944 554 in the name of the same Applicant.

The units for distributing fluids of the above kind are frequently employed in the field of the so-called "domotics", for automating heat management in rooms. Actually, the distributing units, also known in the art under the commercial name of "user satellites" (also referred to in English language as "heating boxes"), comprise sets of tubes, fittings, valves and hydraulic devices previously assembled and contained in a housing capable of simplifying the installation in domestic hydraulic plants.

Summary of the invention

It is an object of the present invention to make a unit for distributing fluids that is improved over the prior art and that, at the same time, can be produced in simple and cheap manner.

More in detail, it is an object of the present invention to make a unit for distributing fluids that is compact and has good performance as far as thermal insulation is concerned.

According to the present invention, the above and other objects are achieved by means of a unit for distributing fluids of the kind mentioned above, as defined in the characterising clause of appended claim 1.

It is to be understood that the appended claims are integral part of the technical teachings provided herein in the present description in respect of the invention.

Brief description of the drawings

Further features and advantages of the invention will become apparent from the following detailed description, given only by way of non limiting example, with reference to the accompanying drawings, in which:

- Fig. 1 is a front elevation of an exemplary embodiment of a unit for distributing fluids according to the present invention;

- Fig. 2 is a front elevation of another exemplary embodiment of a unit for distributing fluids according to the present invention; and

- Fig. 3 is a front elevation of a further exemplary embodiment of a unit for distributing fluids according to the present invention.

Detailed description of the invention

Referring to Fig. 1, reference numeral 10 denotes an exemplary embodiment of a unit for distributing fluids according to the present invention.

Unit 10 includes a main housing 12 internally enclosing a supply pipe 14, a heating circuit 16 and a heat exchange apparatus 18.

Supply pipe 14 comprises an inflow segment 20 arranged to be connected, at its inlet, with a source of sanitary or domestic water under pressure, a first distribution segment 22 intended to deliver cold sanitary water and a second distribution segment 24 intended to deliver heated sanitary water. For instance, the source of sanitary water under pressure is a pipe connected with the water mains. The pipe can suitably come from a condominial riser.

Preferably, unit 10 includes a stop member, e.g. a stop valve 21, located at the inlet of inflow segment 20 of supply pipe 14. For instance, the stop valve is a ball valve 21 of a kind known per se. In the exemplary embodiment illustrated, ball valve 21 is provided with an operating lever (not associated with a reference numeral), which can be manually rotated by a user and is connected to a rotary shutter.

Preferably, unit 10 further includes further stop members, e.g. further stop valves 23 and 25, located at the inlets of the first and the second distribution segments 22 and 24, respectively. For instance, the stop valves are ball valves 23 and 25 of a kind known per se. In the exemplary embodiment illustrated, ball valves 23 and 25 are provided with respective associated operating levers (not associated with reference numerals), which can be manually rotated by a user.

Heating circuit 16 is arranged to be connected with a source of heat carrier fluid under pressure. For instance, the source of heat carrier fluid under pressure is a pipe connected with a boiler. The pipe can suitably come from a condominial riser.

The heat exchange apparatus, preferably a heat exchanger 18, is connected to supply pipe 14 and heating circuit 16 in order to allow heat transfer from heating circuit 16 to supply pipe 14.

Unit 10 includes an inner housing 26 made of a thermally insulating material. Inner housing 26 is enclosed within main housing 12 and in turn internally encloses heating circuit 16, heat exchanger 18 and the second distribution segment 24, while leaving the first distribution segment 22 and the portion of inflow segment 20 located upstream the first distribution segment 22 outside.

Thanks to such features, unit 10 allows avoiding an undesired heat transfer from heating circuit 16 to the first distribution segment 22. In this manner, not only heating in supply pipe 14 of the heated sanitary water intended to be delivered by the second distribution segment 24 is made more effective, but at the same time cold sanitary water intended to be delivered by the first distribution segment 22 is prevented from undergoing a temperature increase, which situation is troublesome in particular in summer time.

Preferably, inner housing 26 is made of a polymeric material with thermally insulating properties, for instance polyurethane foam.

In further preferred manner, inner housing 26 is box shaped.

Preferably, the first distribution segment 22 and the portion of inflow segment 20 located upstream the first distribution segment 22 are located near a first side face 26a of inner housing 26, which face is different and separate from the region through which heating circuit 16 opens to the outside. This feature allows improving the thermal insulation obtained by using inner housing 26.

As it can be seen in the embodiment shown in Fig. 1, the first distribution segment 22 and at least the portion of inflow segment 20 located upstream the first distribution segment 22 are located substantially opposite the first face 26a and preferably parallel thereto.

In further preferred manner, the portion of inflow segment 20 located upstream the first distribution segment 22 is arranged in a region located between the first face 26a and the first distribution segment 22, according to a direction substantially perpendicular to the first face 26a.

Preferably, heating circuit 16 includes a delivery segment 28 arranged to be hydraulically connected, at its inlet, with the source of heat carrier fluid, and a return segment 30 arranged to be hydraulically connected, at its outlet, with the source of heat carrier fluid. Delivery segment 28 is capable of introducing into heating circuit 16 heat carrier fluid at a sufficient temperature for supplying the desired heat amount to supply pipe 14. Conversely, return segment 30 is capable of returning the heat carrier fluid that has been cooled after having undergone a heat exchange with supply pipe 14. Advantageously, delivery segment 28 and return segment 30 open to the outside at a second side face 26b of housing 26, different from the first face 26a, for instance arranged substantially perpendicularly to the latter. Optionally, delivery segment 28 and return segment 30 are substantially parallel to each other.

Preferably, unit 10 further includes a valve assembly 29 and an additional stop member, for instance an additional stop valve 31 , located at the inlets of delivery segment 28 and return segment 30, respectively. For instance, the additional stop valve is a ball valve 31 of a kind known per se. In the exemplary embodiment illustrated, ball valve 31 is provided with an associated operating lever (not associated with a reference numeral), which can be manually rotated by a user. In the illustrated embodiment, valve assembly 29 is made as disclosed in Italian Patent Application n. TO2010A000903 filed by the same Applicant.

Preferably, the further stop valve 25 passes through inner housing 26. More preferably, stop valve 25 is located on the same side as the second side face 26b of inner housing 26.

Preferably, valve assembly 29 and additional stop valve 31 pass through inner housing 26. More preferably, valve assembly 29 and additional stop valve 31 are located in the second side face 26b of inner housing 26.

Preferably, supply pipe 14 extends through heat exchanger 18 so that the latter is hydraulically located downstream inflow segment 20 and upstream the second distribution segment 24. More preferably, supply pipe 14 includes a mixer 32, of a type known per se to the skilled in the art, enclosed within inner housing 26 and hydraulically connected upstream the second distribution segment 24. In the illustrated embodiment, mixer 32 is directly connected to the second distribution segment 24. Moreover, supply pipe 14 includes a first mixing branch 34, which is located in inner housing 26 and is hydraulically connected downstream inflow segment 20 and upstream mixer 32. Moreover, supply pipe 14 includes a second mixing branch 36, which is located in inner housing 26, extends through heat exchanger 18 and is hydraulically connected upstream mixer 32.

In the illustrated embodiment, inflow segment 20 branches into the first mixing branch 34 and the second mixing branch 36. For instance, both the first mixing branch 34 and the second mixing branch 36 are wholly enclosed within inner housing 26.

In the illustrated embodiment, inflow segment 20 extends over a portion thereof outside inner housing 26 and then enters inner housing 26.

Preferably, unit 10 includes a meter or counter for fluids, for instance a litre counter 38, located in supply pipe 14. In the illustrated embodiment, the meter or litre counter 38 is located in inflow segment 20 upstream the first distribution segment 22. For instance, the first distribution segment 22 passes under the meter or litre counter 38.

Optionally, unit 10 includes a flow rate detector, for instance a flow switch 40, located in supply pipe 14. In the illustrated embodiment, flow switch 40 is located in inflow segment 20 upstream heat exchanger 18. Preferably, flow switch 40 is located outside inner housing 26.

Further, heating circuit 16 includes a first partition segment 41 located downstream delivery segment 28 and arranged so as to pass through heat exchanger 18, and an outlet branch segment 42 hydraulically located downstream delivery segment 28 and arranged to be connected upstream one or more radiator devices of an external heating system. Moreover, heating circuit 16 includes a partition valve assembly 44 arranged to partition in controlled manner the flow of primary hot water entering delivery segment 28 between the first partition segment 41 and outlet branch segment 42. For instance, the partition valve assembly includes a three-way partition valve 44, of a type known per se to the skilled in the art, connected downstream delivery segment 28 and upstream the first partition segment 41 and outlet branch segment 42. Preferably, said partition valve 44 is a motor-operated ball valve, for instance of the kind disclosed in published European Patent Application no. EP 1 944 535.

Clearly, the first partition segment 41, outlet branch segment 42 and partition valve assembly 44 are contained in inner housing 26.

Advantageously, unit 10 includes a control unit 46 connected with flow switch 40 and partition valve 44 and arranged to control said partition valve 44 in a manner known per se in the art. In the illustrated embodiment, control unit 46 is located outside inner housing 26 and inside main housing 12.

In the illustrated embodiment, heating circuit 16 includes an inlet branch segment 48 arranged to be hydraulically connected downstream said one or more radiator devices of the external heating system. Return segment 30 is hydraulically connected downstream a second partition segment 45 outgoing from exchanger 18 and downstream inlet branch segment 48. Preferably, inlet branch segment 48 and the second partition segment 45 are connected to return segment 30 through a tee fitting (not associated with a reference numeral). Preferably, control unit 36 is arranged to be connected to the heating system and to manage the functions thereof, for instance to control the radiator devices by means of thermostatic valves, chronothermostats or the like.

In the illustrated embodiment, outlet branch segment 42 and inlet branch segment 48 open to the outside at a side portion of inner housing 26 opposite the first face 26a. Thanks to this feature, it is possible to optimise the space occupation in main housing 12. More in detail, outlet branch segment 42 opens to the outside at a third face 26c of inner housing 26 and inlet branch segment 48 opens to the outside at a fourth face 26d of main housing 26, In the illustrated embodiment, the third face 26c and the fourth face 26d are substantially parallel to each other.

Advantageously, unit 10 further includes an outlet fitting 43 located downstream outlet branch segment 42 and arranged to be hydraulically connected upstream the external heating system (for instance, upstream the radiator devices). Further advantageously, unit 10 further includes an inlet fitting 49 located upstream inlet branch segment 48 and arranged to be hydraulically connected downstream the external heating system (for instance, downstream the radiator devices).

Preferably, outlet fitting 43 lies on inner housing 26 externally thereof. More preferably, outlet fitting 43 is located in correspondence of the third face 26c of inner housing 26.

Preferably, inlet fitting 49 lies on inner housing 26 externally thereof. More preferably, inlet fitting 49 is located in correspondence of the fourth face 26d of inner housing 26.

Preferably, heating circuit 16 includes a heat metering device 52 intended to calculate the heat consumed by the heat carrier fluid in order to generate heated sanitary water and/or to operate the heating system. More in detail, heat metering device 52 is arranged to calculate the heat transferred to heat exchanger 18 through the second partition segment 45 and/or to the external heating system through outlet and inlet branch segments 42, 48. More preferably, heat metering device 52 is associated with return segment 30 and is for instance located upstream additional stop valve 31. Heat metering device 52 is enclosed within inner housing 26.

The operation of unit 10 will be now briefly described.

Supply pipe 14 allows inflow of non- heated (cold) sanitary water through inflow segment 20 and the associated stop valve 21. Litre counter 38 measures the amount of non- heated sanitary water entering unit 10.

If the user wishes the delivery of non-heated sanitary water by opening a cold water tap, the sanitary water is delivered through the first distribution segment 22 and the associated stop valve 23.

If the user wishes the delivery of heated sanitary water by opening a hot water tap, a flow is generated through flow switch 40, which, in a manner known per se, by operating control unit 46, controls partition valve assembly 44. According to control logics known per se, partition valve assembly 44 sends a flow of heat carrier fluid from delivery segment 28 to the first partition segment 41 entering heat exchanger 18. At the same time, a fraction of the cold sanitary water coming from inflow segment 20 and entering inner housing 26 flows along the second mixing branch 36 entering heat exchanger 18, and leaves the latter and, after having been heated, enters mixer 32. Always at the same time, the other fraction of the cold sanitary water coming from inflow segment 20 and entering inner housing 26 flows along the first mixing branch 34 and directly enters mixer 32. In this manner, a mixing of the incoming fluids takes place in mixer 32 in order to bring the sanitary water to the temperature desired by the user, and then the heated sanitary water coming from mixer 32 is delivered through the second distribution segment 24 and the associated stop valve 25.

If the user wishes to operate his/her heating system, control unit 46 controls partition valve assembly 44, in a manner known per se, in order the latter sends a flow of heat carrier fluid from delivery segment 28 to outlet branch segment 42 that has been suitably connected to the heating system.

In case it is desired to deliver heated sanitary water and at the same time to operate the heating system, control unit 46 controls partition valve assembly 44, in a manner known per se, in order to :

- obtain a partition of the heat carrier fluid by partitioning it in controlled manner between the first partition segment 41 and outlet branch segment 42;

- temporarily close outlet branch segment 42 to make the heat carrier fluid flow along the first partition segment 41 for the time necessary to obtain the desired temperature in the second distribution segment 24.

According to a variant embodiment of the invention, control unit 46 can be configured so that, when the heating system is not operating, the unit maintains partition valve assembly 44 in such an arrangement that the whole of the heat carrier fluid coming from delivery segment 28 is always diverted towards the first partition segment 41. In this manner, heated sanitary water can be generated in very short times, without significantly affecting the actual heat consumption.

Accounting of the overall heat consumption is performed by heat metering device 52. The heat carrier fluid cooled in order to generate heated sanitary water leaves heat exchanger 18 through the second partition segment 45, whereas the heat carrier fluid cooled in order to supply the heating system with thermal energy enters through inlet branch segment 48. Both the second partition segment 45 and inlet branch segment 48 end into return segment 30 ending at heat metering device 52. In this manner, the overall heat loss in the heat carrier fluid due to both the use of heated sanitary water and the use of the heating system is perceived.

Referring to Fig. 2, reference numeral 110 denotes a further embodiment of a unit for distributing fluids according to the present invention.

In such a further embodiment, elements and components that are structurally similar to or have the same function as those of the preceding embodiment are associated with the same reference numerals as used in the preceding embodiment.

One of the differences between the embodiment shown in Fig. 1 and the embodiment shown in Fig. 2 is that distributing unit 110 comprises a (first) distribution manifold 60 hydraulically connected downstream the first distribution segment 22. Preferably, in this embodiment, the further stop valve 23 is lacking, since the first distribution segment 22 is directly connected with distribution manifold 60. Moreover, distribution manifold 60 has a plurality of distribution fittings 62, each of them being equipped with a suitable stop member, for instance a corresponding stop valve 64, possibly a ball valve.

Preferably, the first distribution manifold 60 is oriented so that its longitudinal extension is substantially parallel to the plane on which the second side face 26b of inner housing 26 lies and, more preferably, substantially perpendicular to the plane on which the first side face 26a lies.

In a further preferred manner, distributing unit 110 also includes a second distribution manifold 66 hydraulically connected downstream the second distribution segment 24. Preferably, in this embodiment, the further stop valve 25 is lacking, since the second distribution segment 24 is directly connected with distribution manifold 66. Moreover, the second distribution manifold 66 has a plurality of distribution fittings 68, each of them being equipped with a suitable stop member, for instance a corresponding stop valve 70, possibly a ball valve.

Preferably, the second distribution manifold 66 is oriented so that its longitudinal extension is substantially parallel to the plane on which the second side face 26b lies and, more preferably, substantially perpendicular to the plane on which the first side face 26a lies. In further preferred manner, the second distribution manifold 66 is substantially parallel to the first distribution manifold 60. In the illustrated embodiment, the first and the second distribution manifolds 60, 66 are mutually spaced apart in a direction substantially parallel to side faces 26a, 26b, 26c, 26d of the housing and, for instance, they face each other and are arranged one above the other in correspondence of at least a longitudinal portion thereof,

An optional difference between the embodiment shown in Fig. 1 and the embodiment shown in Fig. 2 is that the first distribution segment 22 of fluid distributing unit 110 is arranged in a region located between the first face 26a and the portion of inflow segment 20 located upstream the first distribution segment, according to a direction substantially perpendicular to the first face 26a. For instance, the first distribution segment 22 passes over the meter or litre counter 38.

Referring to Fig. 3, reference numeral 120 denotes a further embodiment of a unit for distributing fluids according to the present invention.

One of the differences between the embodiment shown in Figs. 1 and 2 and the embodiment shown in Fig. 3 is that distributing unit 120 comprises an inflow segment 50 for the sanitary hot water, hydraulically connected with a sanitary hot water supply pipe, which can come from a condominial riser and replaces heat exchanger 18.

Preferably, this embodiment includes a third stop valve 51, located in correspondence of inflow segment 50 of sanitary hot water, and a second meter or second litre counter 38a also located in inflow segment 50. The second litre counter 38a measures the amount of heated sanitary water entering unit 120.

The technical features distinguishing the different variants and embodiments described and shown from one another can be freely mutually exchanged, provided they are compatible. For instance, as the skilled in the art can appreciate in view of the present description, in further variant embodiments, in unit 10 for distributing fluids according to the first embodiment of the invention the first distribution segment 22 can be located in a position similar to that shown in unit 110 for distributing fluids according to the second embodiment, and vice versa

Of course, while keeping the inventive principle unchanged, the embodiments and the construction details can be widely changed with respect to what has been described and shown by way of non limiting example only, without thereby departing from the scope of the invention as defined in the following claims. REFERENCE NUMERALS

10 Unit for distributing fluids (first embodiment)

12 Main housing

14 Supply pipe

16 Heating circuit

18 Heat exchange apparatus

20 Inflow segment

21 Stop member

22 First distribution segment

23 Further stop valve

24 Second distribution segment

25 Further stop valve

26 Inner housing

26a First side face of the inner housing

26b Second side face of the inner housing

26a Third side face of the inner housing

28 Delivery segment of the heating circuit

29 Valve assembly

30 Return segment of the heating circuit

31 Additional stop valve

32 Mixer

34 First mixing branch

36 Second mixing branch

38 Litre counter

38a Second litre counter

40 Flow switch

41 First partition segment

42 Outlet branch segment

43 Outlet fitting

44 Partition valve

45 Second partition segment

46 Control unit

48 Inlet branch segment

49 Inlet fitting Sanitary hot water inflow segment

Third stop valve

Heat metering device

Unit for distributing fluids (second embodiment)

Unit for distributing fluids (third embodiment)

First distribution manifold

Distribution fittings

Stop valves

Second distribution manifold

Distribution fittings

Stop valves

Claims

Patent claims

1. Unit for distributing fluids (10), comprising a main housing (12) which encloses therein:

- a supply pipe (14) comprising an inflow segment (20) arranged to be connected, at the inlet thereof, with a pressurised domestic water source, a first distribution segment (22) intended to provide cold domestic water, and a second distribution segment (24) intended to provide hot domestic water;

- a heating circuit (16) arranged for being connected with a pressurised heat carrier fluid source; and

- heat exchange means (18) connected to said supply pipe (14) and said heating circuit (16) so as to allow a heat transfer from said heating circuit (16) to said supply pipe

(14);

characterised in that said unit (10) further comprises an inner housing (26) made of thermally insulating material and enclosed within said main housing (12); said inner housing (26) enclosing said heating circuit (16), said heat exchange means (18) and said second distribution segment (24), while leaving outside said first distribution segment (22) and at least the portion of said inflow segment (20) which is located upstream of said first distribution segment (22).

2. Unit according to claim 1, wherein said inner housing (26) is made of a polymer material having thermal insulation properties, such as polyurethane foam.

3. Unit according to claim 1 or 2, wherein said inner housing (26) is box- shaped.

4. Unit according to claim 3, wherein said first distribution segment (22) and at least the portion of said inflow segment (20) which is located upstream of said first distribution segment (22) are located near a first face (26a) of said inner housing (26) which is different and separate from the region (26b) of said inner housing (26) through which said heating circuit (16) opens to the outside.

5. Unit according to claim 4, wherein said first distribution segment (22) and at least the portion of said inflow segment (20) located upstream of said first distribution segment (22) are arranged substantially in front of said first face (26a).

6. Unit according to claim 5, wherein said at least one portion of the inflow segment (20) is located between said first face (26a) and said first distribution segment (22).

7. Unit according to any of claims 4 to 6, wherein said first face (26a) belongs to the lateral surface of said inner housing (26).

8. Unit according to any of claims 4 to 7, wherein said heating circuit (16) includes:

- a delivery segment (28) arranged for being hydraulically connected, at the inlet thereof, to said heat carrier fluid source;

- a return segment (30) arranged for being hydraulically connected, at the outlet thereof, to said heat carrier fluid source;

said delivery segment (28) and said return segment (30) opening to the outside through a lateral face (26b) of said inner housing (26) which is substantially perpendicularly directed relative to said first face (26a).

9. Unit according to any of claims 4 to 8, wherein said heating circuit (16) comprises:

- an outlet branch segment (42) located downstream of said delivery segment (28) and arranged for being connected upstream of one or more radiator devices of an outer heating system;

- an inlet branch segment (48) located upstream of said return segment (30) and arranged for being hydraulically connected downstream of said one or more radiator devices of said outer heating system.

10. Unit according to claim 9, wherein said outlet branch segment (42) and said inlet branch segment (48) open to the outside through a lateral portion (26c, 26d) of said inner housing (26) which is in an opposite position relative to said first face (26a).

11. Unit according to claim 9 or 10, wherein said heating circuit (16) includes:

- a partition segment (41) located hydraulically downstream of said delivery segment (28), and passing though said heat exchange means (18), and

- a partitioning valve means (44) arranged for partitioning in a controlled manner the flow rate of primary hot water entering into said delivery segment (28) between said partition segment (41) and said outlet branch segment (42).

12. Unit according to any of the preceding claims, further comprising a mixer (32) enclosed in said inner housing (26) and hydraulically connected upstream of said second delivery segment (24); said supply pipe (14) comprising a first mixing branch (34) located at least partially in the inner housing (26) and hydraulically connected downstream of said inflow segment (20) and upstream of the mixer (32), and a second mixing branch (36) located in said inner housing (26), hydraulically connected downstream of said inflow segment (20), passing through said heat exchange means (18), and hydraulically connected upstream of said mixer (32).

13. Unit according to any of the preceding claims, wherein said heating circuit (16) includes a heat metering device (52) intended to meter the heat used by the heat carrier fluid in order to generate hot domestic water and/or in order to operate the heating system.

14. Unit according to claim 13, wherein said heat metering device (52) is associated with said return segment (30).

15. Unit according to any of the preceding claims, further comprising at least one among the elements comprised in the list consisting of:

- a stop valve (25) located at the outlet of said second distribution segment (24) and passing through said inner housing (26);

- a valve assembly (29) located at the inlet of said delivery segment (28) and passing through said inner housing (26);

- a stop valve (31) located at the outlet of the return segment (30) and passing through said inner housing (26);

- an outlet fitting (43) located downstream of said outlet branch segment (42) and lying on the exterior of said inner housing (26); and

- an inlet fitting (49) located upstream of said inlet branch segment (48) and lying on the exterior of said inner housing (26).

16. Unit according to any of the preceding claims, wherein said heat exchange means (18) include a sanitary hot water inflow segment (50) hydraulically connected to a domestic hot water supply pipe.