FR2495287A1 - Domestic chimney heat recovery jacket - has protected pipes connected to central heating circuit to heat fluid - Google Patents

Abstract

The jacket recovers heat from the fire in a domestic chimney, to warm central heating fluid. It has an assembly of pipes connected together and to the central heating circuit. The fluid flows inside these. Each pipe (33) is covered, at least partly, by a protecting cover (34) of high heat conduction metal. The pipe connections are left open. The opes are virtually parallel, spaced from each other,and connected to a collector (35,36,37) perpendicular to them. The assembly rests on the floor on adjustable jacks (38).

Description

DEVICE COMPRISING MOLDED SHEATH TUBES FOR THE RECOVERY OF HEAT FROM A FIREPLACE
The present invention relates to a recovery device intended to be placed in the open hearth of a chimney for domestic use, with a view to recovering the heat released by the combustion of solid fuels placed inside the hearth, in particular for heating. other rooms in a living space.

 It is known, in fact, that devices of this kind can be connected to a conventional central heating installation in which the chimney constitutes, beside the main source of heat formed by the boiler, an evening of auxiliary heat making it possible to save , when the chimney is lit, part of the fuel burned in the boiler.

 More specifically, the present invention aims to improve a heat recovery system of known type comprising at least a network or bundle of separate tubes, substantially parallel, within which circulates the heat transfer fluid. All of the tubes of the network can be bent so as to present a substantially horizontal part designed to support the fuel to be burned in the hearth and another substantially vertical part constituting the bottom of the hearth. The set of tubes is conventionally connected at the bottom to a cold water collector and at the top to a hot water collector which are connected to the pipes of the central heating installation.

 The recovery device aimed above, has many drawbacks: the coolant circulation tubes, with thin walls do not benefit from effective protection against thermal shock or against significant corrosion caused by direct attack of the wall of the tubes by the flames of the hearth. In addition, the part of the tubes which constitutes the bottom of the hearth can be subjected to significant mechanical shocks occurring during the filling of the hearth with solid fuel and in particular during the firing of large logs of wood. It follows that the tubes which are called upon to support the solid fuel do not have, due to their thin wall, all the desired mechanical characteristics and in particular good impact resistance. Taking into account the manufacturing tolerances, the tubes have a wall thickness which can vary within wide proportions so that they often have weakened wall zones which obviously have very low corrosion resistance and mechanical strength.

 The present invention aims to remedy the aforementioned in @ onadvantages and for this purpose, it proposes to describe @@ heat recovery device of the type mentioned above, in which the tubes are coated with a protective metal or made of a good heat conductive and fire resistant alloy, this sheath being overmolded around the aforementioned tubes.

The advantage of a protective sheath molded around each of the tubes of the device is threefold: in the first place, the protective sheaths of course make it possible to protect the tubes against corrosion and also to improve their mechanical resistance, in particular in the part tubes which is intended to receive solid fuel. Second link @, @e overmolding of a good conductive metal along the tubes of the device according to the invention has the effect of improving the diffusion of heat over the entire length of the tubes and increasing the thermal inertia d @ device; moreover, as the sheathed tubes have a larger section than the unsheathed rods, this results in an increase in the heating surface and a significant increase in the heat output. Thirdly, since the tubes are protected against corrosion and significant thermal shock and their mechanical strength is increased by the presence of protective sheaths, it is possible to use in the manufacture of the heat recovery device, thinner-walled tubes having wide manufacturing tolerances and, consequently, of lower cost price.

 In terms of manufacturing, the overmolding of the tubes of the device constitutes a simpi operation using a mold with two shells of the conventional type; in addition, this overmolding operation can be put to use for the execution of auxiliary members, in particular fins formed on the front part of the substantially vertical section of the bundle of tubes, or even bosses constituting the housing of the jacks. by which the recovery device rests on the floor of the chimney.

 The present invention therefore relates to a device for recovering the heat given off by the hearth of a residential chimney, with a view in particular to heating the heat transfer fluid of a central heating installation, this device comprising at least one network or bundle of separate tubes connected by manifolds to the central heating installation and, inside which the heat transfer fluid can circulate, characterized in that each of the aforementioned tubes is, over at least part of its length coated with a protective sheath made of metal which is a good conductor of heat and resistant to fire, said sheath being overmolded around said tube.

 Among the metals which are good conductors of heat and resistant to fire and which can be used for overmolding protective sheaths, mention may be made of gray cast iron or a light alloy such as an alloy based on aluminum and copper.

 In a preferred embodiment, the protective sheath overmolded around each of the tubes of the network (s) of tube (s) extends over substantially the entire length of said tubes without covering their two zones of connection to the collectors; the tubes of the network (s) of tube (s) are substantially parallel, separated from each other and connected at each end to a collector extending perpendicular to said tubes.

 The external section of the protective sheaths of the overmolded tubes can be arbitrary as long as it does not complicate the demolding operations. It is preferred that the outer section of the protective sheaths takes the form of a square with cut sides.

 The heat recovery device according to the invention comprises, on the one hand, a part designed to support the hearth and on the other hand, a part constituting the bottom of the hearth. In a first embodiment, the recovery device according to the invention comprises a single re seaJ of tubes coated with an overmolded protective sheath, each tube of the network being bent so as to define at least two sections: on the one hand , a first section equipping the part of the device supporting the hearth and, secondly, a second section equipping the part of the device constituting the bottom of the hearth. In this case, the axes of the first and second sections of tubes define at least two intersecting planes the bent tubes are advantageously connected at at least one of their ends to a collector along which a protective angle is attached, one of the wings of which covers the ends of the tubes which are not coated with the protective sheath; the second section of each short tube may include an intermediate section connected at right angles to the first section and an inclined end section connected to the intermediate section; for each bent tube in the network, the inclination of the terminal section relative to the first section is such that the two sections consider converge towards the focus.

 In a second embodiment, the heat recovery device according to the invention comprises two networks of substantially rectilinear tubes coated with an overmolded protective sheath, one of the networks of tubes equipping the part of the device supporting the hearth and the another network of tubes equipping the part of the device constituting the bottom of the hearth. In this case, the two networks of rectilinear tubes are arranged in two intersecting planes whose dihedral angle is less than or equal to a straight line; they are connected to each other by an intermediate collector common to the two networks, the aforementioned collectors being substantially parallel and perpendicular to the axes of the straight tubes of the two networks; on the two end collectors can also be welded a protective angle extending substantially over the entire length of said collectors.

 Advantageously, the recovery device according to the invention rests on the floor of the chimney by means of adjustable cylinders, the threaded housing of which is formed in a boss formed by molding with the protective sheath of the tubes.

 To better understand the object of the present invention, there will be described below, by way of purely illustrative and nonlimiting examples, several embodiments shown in the accompanying drawing.

On this drawing
- Figure 1A is a schematic enselr.ble view of a central heating installation implementing a heat recovery device according to the invention
- Figure 1B is an elevational view of a heat recovery device according to the invention
- Figure 2 is a side view along II-II of Figure lB
- Figure 3 is a section of a sheathed tube along III
III of Figure 2 ;;
- Figure 4 is a section of a sheathed tube in line with one of the adjustable jacks which support the recovery device, this section being made according to IV-IV of Figure 2
- Figure 5 is a side view similar to that of Figure 2 showing n second embodiment of the heat recovery device
- Figure 6 is a side view similar to that of Figure 2 showing a variant of the first embodiment shown in Figures 1B and 2.

 Referring to FIG. 1A of the drawing, it can be seen that a schematic representation has been made of a central heating installation of a living space comprising, on the one hand, a main source of heating, namely a boiler l of the conventional type and, on the other hand, an auxiliary heating source formed by a chimney 2 for domestic use. The boiler 1 supplies hot water to the radiators 3 (only one of which is shown).

 In the liter of the chimney 2 is disposed a heat recovery device designated by 4 as a whole, the detailed structure of which is illustrated in FIGS. 1B and 2 to 4. A pipe 5 connected to the lower part of the recovery device 4 communicates with a pipe 6 connected between the lower part of the radiator 3 and a multi-way valve 7. On the valve 7, there is also connected a pipe 8 communicating with the upper part of the recovery device 4 as well as the coil 9 of the boiler 1 which is itself connected by a pipe 10 to the upper part of the radiator 3.

 Depending on the position given to the multi-way valve 7, the water circulating inside the central heating installation can be heated either only by the boiler 1, or by means of the recovery device 4, when from solid fuel, such as wood or charcoal is burned inside the chimney 2 either still by these two heat sources at the same time.

 As is better visible in FIGS. 1B and 2, the heat recovery device 4 comprises a network or a single bundle of nine tubes 11a of circular section coated with a protective sheath lib of substantially section constant which is overmolded around each tube 11a. The protective sheath llb is made of a metal or an alloy which is a good conductor of heat and resistant to fire, noxiously made of cast aluminum; the tubes 11a can be made of copper or another metal or alloy which is a good conductor of heat; the protective sheath 11b has, in this example, an outer section in the form of a square with cut sides; it covers each tube 11a over substantially its entire length; willows the two lic ends of the tubes 11a are not coated by the protective sheath 11b.

 The nine tubes 11a of the recovery device 4 are substantially parallel and regularly spaced from each other by a short distance less than the dimension of their protective sheath 11b measured between two cut sides.

They are bent in two ends so that their axes deflate between them three intersecting planes: a horizontal plane, an incermediate vertical plane and an inclined end plane whose inclination with respect to the horizontal plane is about 45. Thus, the set of tubes 11a coated with their protective sheath 11b have three sections: a horizontal section 14a, an intermediate vertical section 14b and an inclined end section 14c. The elbows of the tubes 11a are curved and not straight, so less loss of charter inside the tubes corresponding to the change in direction
The protective tubes ilo of the set of tubes 11a have two of their four cut sides which are aligned while their two other cut sides are arranged parallel to each other.

 The horizontal section 14e of the network of tubes lla is connected by its unsheathed ends lic to a cold water collector 15 while, similarly, the inclined end section 14c of the tubes is connected by its unsheathed ends lic to a hot water collector 16. The two collectors 15, 16 are substantially parallel and perpendicular to the sheathed tubes lla of the network. Conventional connections (not shown) connect the two collectors 15 and 16 to the pipes 5 and 8 of the central heating installation. The two collectors 15 and 16 consist of sections of tube not coated with a protective sheath, including the diameter of the die; lr is greater than that of the tubes lla; on the collector ter 15 is sodged a protective angle bracket 17 which extends over the entire part of said collector which is connected to the network of sheathed tubes lla. The substantially ho rizontale wing of the protective angle 17 covers not only the manifold 15 but also the ends lic of the tubes lla which are not coated by the protective sheath llb; the wing considered comes substantially in the extension of the plane defined by the upper cut sides of the ducts of horizontal section 14a; the substantially vertical wing of the angle iron 17 has a width which is slightly greater than the outside diameter of the collector 15. In the same way, a protective angle 18 is welded to the hot water collector 16; it comprises> on the one hand, a substantially horizontal wing which covers the upper part of the manifold 16 and, on the other hand, an inclined wing making an angle of approximately 45 relative to the above-mentioned horizontal wing. The wing.

inclined protective angle 18 covers not only the front part of the manifold 16 but also the unsheathed ends lic of the network of tubes lla; it comes substantially in line with the plane formed by the aligned cut sides of the sheaths of the inclined section 14c (FIG. 2).

 S @ r the protective angle 17 are added by welding curved metal elements 19 projecting from the horizontal section 14a of the sheathed tubes lla.

 The heat recovery device 4 rests on the floor of the chimney by four adjustment cylinders 20 making it possible to adjust its level. The two end tubes 11a of the network of tubes each carry a pair of adjustment cylinders 20. Each cylinder is made up, (FIG. 4) of a boss 21 advantageously molded with the protective sheath 11b of the tubes. A screw 22 whose head rests on the floor of the chimney engages inside a threaded bore made in the boss 21. The operation of the screw 22 of the adjusting cylinder can be carried out directly, without tools , or using a pin (not shown).

 In this example, the horizontal section 14a of the sheathed tubes 11a constitutes a combustion grate on which are placed solid fuels such as wood or coal; the vertical section 14b and the inclined end section 14c of the sheathed tubes lla constitute the bottom of the hearth b the inclined end section 14c allows the heat released by combustion to be returned to the vertical part 14 ′ cu the horizontal part 14a of the sheathed tubes 11a, so as to improve the recovery of calories escaping through the chimney flue disposed above the hearth.

 The sheaths llb of good conductive and fire-resistant metal which are overmolded around the tubes 11a have the function of protecting them against corrosion and of improving their mechanical resistance in particular their resistance to. shocks. In addition, the overmolded sheaths llb protect the tubes 11a against thermal shock, ensure a more regular distribution of heat over their entire length and simultaneously give the recovery device the desired thermal inertia. Compared to a recovery device provided with non-sheathed tubes, that which has just been described has the advantage of benefiting from a larger heating surface, since the outer section of the sheathed tubes is greater than the section tubes which are not. In addition, in order to increase the heating surface and thus improve heat recovery, longitudinal fins, not shown, which have come from molding with the protective sheaths, may be provided. ilb, these fins extending over the vertical section 14b of the tubes 11a and on the side of said tabs which is opposite the hearth. At surpl @ s, the bosses 21 of the adjustment cylinders 20 have advantageously come from molding with the protective sheath llb of the tubes 11a.

 The production of the recovery device with sheathed tubes does not raise any difficulties: the previously bent tubes 11a with their collector 15, 16 are assembled by welding; then this assembly is placed in a mold with two shells of conventional type so as to overmold the protective sheaths llb around the tubes 11a, the protective sheaths 11b of the two end tubes 11a having come from molding with the bosses 21 adjustment cylinders; once the molding topography is accomplished, the threaded bores are cleaned inside the bosses 20, the protective angles 17, 18 are welded to the two collectors 15, 16 and the screw 22 of the adjustment cylinders.

In the second embodiment shown in FIG. 5, the heat recovery device which has been designated by 30 as a whole is composed not of a single network or bundle of sheathed tubes but of two networks 31, 32 arranged in two intersecting planes forming between them a dihedral angle of about 45
The gain tubes of the two networks 31, 32 have the same structure: they comprise a section of rectilinear tube 33 around which is overmolded a protective sheath 34 made of metal which is a good conductor of heat and resistant to fire, for example of cast iron. aluminum. Inside each of the networks, the tubes 33 coated with their protective sheath 34 are substantially parallel and regularly spaced from one another. The outer section of the protective sheaths 34 has the configuration of a square with cut sides, the tubes 33 of the network 32 are connected by their ends which are not coated with the protective sheath 34, on the one hand, to a cold water collector 35 and, on the other hand, to an intermediate collector 36 common to the two networks. The two collectors 35 and 36 are substantially parallel and perpendicular to the tubes of the network 32; the overmolded tubes of the network 31 are connected at the bottom to the intermediate collector 36 and at the top to a hot water collector 37.

 The two end tubes of the network 32 each carry a pair of adjustment jacks 38 similar to the jacks 20 of FIG. 4. The network of tubes 32 acts as a combustion grate on which the solid fuels (wood or coal) while the network of tubes 31 constitutes the inclined bottom of the hearth. The advantages provided by the alternative embodiment of FIG. 5 are substantially identical to those of the embodiment of FIGS. 1b 3 and 4.

 In the variant of FIG. 6, the heat recovery device, designated by 40 as a whole, comprises a unique network of bent tubes 41 of circular section coated with a protective sheath 42 for example made of cast aluminum which is overmolded around each bent tube 41. The outer cross section of the protective sheaths 42 also has the configuration of a square with compacted sides. The tubes 41 are connected at the bottom @@ to a cold water collector 43 and at the top to a hot water collector 44; the two collectors 43, 44 are parallel and perpendicular to the tubes 41. The bent tubes 41 coated with their protective sheath 42 are substantially parallel and regularly spaced from one another; the axes of the bent tubes 4 @ define two substantially perpendicular planes. The network of bent tubes 41 thus has a horizontal section 43a constituting the grate or the floor of the hearth and a vertical section 43b constituting the bottom of the hearth. The recovery device before resting on the floor of the chimney by two pairs of adjustable jacks @ 4 at neck points similar to those of FIG. 4.

 The variant of FIG. 6 provides the same advantages, in a sense, as the embodiment of FIG. 5 or that of FIGS. 1b and 2.

 It is understood that the above embodiments described this sunt no limitation and po @@ ront give rise to any desirable changes without departing from the scope of the invention.

Claims (10)

 1 - Device for recovering the heat released by the hearth of a residential chimney, with a view in particular to reheating the heat transfer fluid of a central heating installation, this device comprising at least one network or bundle of separate tubes connected by manifolds at the central heating installation and inside which the heat transfer fluid can circulate, characterized in that each tube (ila, 33, 41) of the device is, at least over part of its length, coated with 'a protective sheath (11b, 34, 42) of metal which is a good conductor of heat and resistant to fire, said sheath being overmolded around said tube.  2 - Device according to claim 1, characterized in that the protective sheath (llb, 34, 42) molded around each of the tubes (lla, 33> 41) extends over substantially the entire length of said tubes, without covering their two connection zones (lic) to the collectors.  3 - Device according to one of claims 1 or 2, characterized by the fact that the tubes (11a, 33> 41) (or one or more) network (s) of tubes are substantially parallel, separated from one another and connected, at each end, to a manifold (15, 16, 35, 36, 37, 43, 44) extending perpendicular to said tubes.  4 - Device according to one of claims 1 & 3, characterized in that it comprises> on the one hand, a part (14a, 32, 43) designed to support the hearth and> on the other hand, a part (14b, 14c, 31, 43b) constituting the bottom of the hearth.  5 - Device according to claim 4, characterized in that it comprises a single network of tubes (11a, 41) coated with an overmolded protective sheath (11b, 42), each tube of the network being bent so to define at least two sections: on the one hand, a first section (14a, 43a) equipping the part of the device supporting the hearth and, on the other hand, a second section (14b-14c, 43b) equipping the part of the device constituting the bottom of the hearth.  6 - Device according to claim 5, characterized in that the axes of the first and second sections of bent tubes (14a, 14b-14c and 43a, 43b) define at least two intersecting planes.  7 - Device according to claim 6, characterized in that the bent tubes (lia) of the network are connected at at least one of their ends to a collector (15, 16) along which is fitted a protective angle (17, 18), one of the wings of which covers the ends (11c) of the tubes, which are not coated with the protective sheath (11b).  8 - Device according to claim 4, characterized in that it comprises two networks (31, 32) of substantially rectilinear tubes (33) coated with an overmolded protective sheath (34), one of the networks of tubes ( 31) equipping the part of the device supporting the hearth and the other network of tubes (32) equipping the part of the device constituting the bottom of the hearth.  9 - Device according to claim 8, characterized in that the -two networks (31, 32) of rectilinear tubes are arranged in two intersecting planes and are connected together by an intermediate collector (36) common to the two networks.  10 - Device according to one of claims 1 to 9, characterized in that it rests on the floor of the chimney by means of adjustable jacks (20, 38, 44), whose threaded housing is formed in a boss ( 21) molded with the protective sheath (11b, 34, 42) of the tubes.