EP1021687B1 - Gas water heater - Google Patents

Abstract

The invention concerns a gas water heater comprising a reservoir (1) equipped with an cold domestic water supply (2) intake tube and an outlet tube for hot domestic water (3), a heating element (6), penetrating inside the reservoir (1) through an opening (4) thereof, and which contains a combustion chamber (24), wherein is arranged a burner (7), and an exhaust duct for burnt gases emerging through an orifice (11) outside the reservoir (1). The heating element (6) further contains at least a first longitudinal duct (22c) and at least a second longitudinal duct (22h), communicating with each other through a passage (35) formed at the heating element (6) end located inside the reservoir (1) and communicating respectively with a cold water inlet (27) and a hot water outlet, provided at the heating element (6) end located outside the reservoir (1) and capable of being connected to a hot water circuit.

Description

The present invention relates to a gas water heater of the type including a water tank fitted with a cold water inlet tube and a domestic hot water outlet tube, a gas, means for supplying an air / combustible gas mixture to the burner, and a hollow elongated heater, which is engaged inside the tank, through a single opening of this one, and which is provided with a single flange by means of which it is attached to the tank and which seals the opening of the the latter, said heating body containing a combustion chamber, in which the burner is arranged, and a gas evacuation channel burned connecting said combustion chamber to an outlet of the burnt gas provided at one end of the heating body located at outside the tank.

Known gas water heaters of this type are described in documents IT-1 178 296 and IT-1 182 951. In these water heaters known, the heating body is produced in the form of a bent tube in the shape of an inverted U, the two branches of which pass through the disc-shaped mounting flange, the combustion chamber being formed in one of the two branches of the U and the remaining part of the inverted U-shaped tube serving as a gas evacuation channel burned. An advantage of these known water heaters is that the body of heater can be dismantled for inspection or replacement, and that the various water, gas and smoke can be carried out on the same side of the water heater, in this case the underside. These known gas water heaters have further advantage of being able to use a water heater tank standard electric, which is produced in large series, so little expensive, the heater being simply installed in place electrical resistance of the electric water heater. However, these known gas water heaters are intended only to produce domestic hot water and therefore do not allow to produce same time hot water for a heating circuit.

We also know of mixed boilers, which are capable to produce both domestic hot water and hot water for a heating circuit and the heating body of which passes through completely, from top to bottom, the water tank. However, these mixed boilers do not allow disassembly of the body heating and the various air, water, gas and smoke connections do not can be done on the same side of the tank. In addition, they do not cannot use a single opening tank as a inexpensive standard electric water heater tank but require a special tank.

In addition, document EP-A-0635 683 describes a mixed water boiler fitted with a gas burner; this boiler has a burner and a heat exchanger combined into a unit which enters a sanitary water storage container through a single opening of the same. The water heater in this document has a single wall which separates the projecting parts, intended for increasing the heating surface, domestic water.

The present invention therefore aims to provide a water heater gas of the type defined in the preamble, in which the heating body is attached to the tank by a single flange and which is capable of produce not only domestic hot water, but also hot water for a heating circuit.

In particular, the gas water heater according to the invention comprises a tank of water fitted with a sanitary cold inlet tube and a domestic hot water outlet, a gas burner, means for bring an air / combustible gas mixture to the burner, and a body of hollow and elongated heater, which is engaged inside the tank, through a single opening thereof, and which is provided a single flange by means of which it is fixed to the tank and which seals the opening thereof, said body of heater containing a combustion chamber, in which is arranged the burner, and a flue gas evacuation channel connecting said combustion chamber to a burnt gas outlet provided at one end of the heating body located outside the tank, characterized in that said heating body also contains at least a first channel and at least a second channel which extend from said end of the heating element located outside the tank up to a opposite end of the heater located inside the reservoir, said first and second channels communicating with one the other by a passage formed in said opposite end of the body heating, and communicating respectively with an orifice cold water inlet and with a hot water outlet which are provided at the end of the heating body located outside the tank and are connectable to a heating water circuit and in this that the heater has the general shape of a hollow cylinder double wall, having an internal cylindrical wall and a wall cylindrical external, with several longitudinal partitions of partitions that extend radially between the inner walls and external and which define several longitudinal channels distributed circumferentially around the axis of the cylinder of the heating body.

Thanks to such an arrangement, the heating body can be easily installed in a tank with a single opening, and it can produce domestic hot water as well as water hot for a heating circuit.

la figure 1 est une vue en partie en élévation latérale et en partie en coupe montrant un chauffe-eau à gaz selon l'invention;

la figure 2 est une vue en coupe vertical du corps de chauffe du chauffe-eau de la figure 1, la coupe étant faite suivant la ligne II-II de la figure 3;

la figure 3 est une vue en coupe suivant la ligne III-III de la figure 2.

Other characteristics and advantages of the present invention will emerge more clearly during the description which follows of an embodiment of the gas water heater, given by way of example with reference to the appended drawings in which:

Figure 1 is a view partly in side elevation and partly in section showing a gas water heater according to the invention;

Figure 2 is a vertical sectional view of the heater body of the water heater of Figure 1, the section being taken along line II-II of Figure 3;

Figure 3 is a sectional view along line III-III of Figure 2.

The gas water heater shown in Figure 1 includes, in known manner, a reservoir 1, which can be arranged vertically and whose bottom 1a is provided with a first tube 2 (ENTRY E.F.S.) and with a second tube 3 (EXIT E.C.S.). Tube 2 is connected or connectable, from known manner, to a pipe (not shown) itself connected to a network domestic cold water supply (ER.F.S.), while tube 3 is connected or connectable, in a known manner, to another pipe (not shown) itself connected to a domestic hot water distribution network sanitary (E.C.S.).

The bottom 1a of the tank 1 comprises in known manner, a opening 4 which, in service, is hermetically sealed by a flange 5 forming part of a heating body 6. As shown in FIG. 1, the heating element 6 penetrates inside the tank 1, through the opening 4, over a vertical distance corresponding to part of the height of the tank, for example approximately two-thirds of the height of the tank.

Inside the heating body 6, which is hollow, is housed a burner 7 (not shown in Figure 1, but visible in Figures 2 and 3). The burner 7 is supplied with combustible gas by a tube 8 connected to a block conventional gas flow control and / or regulation (not shown) itself connected to a source of combustible gas connected to a source of combustible gas (gas distribution network or fuel gas storage). The burner 7 is also supplied with air by a ventilator 9. The burnt gases and the fumes are evacuated from the body heating 6 by a discharge opening 11, which is located below the flange 5 and which is connected by a pipe 12 to a chimney, a suction cup or similar (not shown) leading the burnt gases and fumes to in the atmosphere outside the building in which the water heater. The air sent to the burner 7 by the fan 9 can be advantageously preheated before reaching the fan 9. For this purpose, the inlet 9a of the fan 9 can be connected by a pipe 13 (shown schematically as a single solid line in Figure 1) to a box 14 surrounding the pipe 12 near the orifice 11 evacuation of burnt gases. The box 14 is itself connected to a pipe 15 which surrounds pipe 12 and which leads to a fresh air intake (not shown). Thus, the fresh air admitted through the pipe 12 heats up gradually in contact with the hot external surface of the pipe 12, which is traversed in reverse by the burnt gases, as it progresses towards the box 14, and the fresh air thus heated is led by the pipe 13 to the fan 9 which discharges it towards the burner 7.

The tank 1 is placed inside a casing 16 and the space between the casing 16 and the reservoir 1 is filled, so known, of a material 17 having good insulating properties thermal, such as plastic foam, glass wool or rock wool.

In service, tank 1 is completely filled with water and the water is in contact with the outer surface of the heating body 6. Thus, when the burner is lit, the heat from the burnt gases is transmitted to the heating element which in turn transmits it to the water contained in the tank 1.

The water heater described so far in broad outline can be considered known. We will now describe its particularities which, according to the invention reside in the body structure of heater 6 which is designed to also produce hot water for a heating circuit.

According to a preferred embodiment of the heating body 6, this has the general shape of a double-walled hollow cylinder like shown in Figure 2. It has an internal cylindrical wall 18 and a external cylindrical wall 19, with several longotudinal partitions of separation 21 which extend radially between the inner and outer walls and which define several longitudinal channels, for example eight channels longitudinal 22a to 22h (Figure 3), which are distributed circumferentially around the axis of the cylinder of the heating body 6 and which, in service, are traversed by water to be heated in a manner which will be described in detail plus law.

Several fins or longitudinal ribs 23 radially projection on the inner surface of the inner wall 18 of the heating body 6 and extend longitudinally over at least part of the length axial of said heating body, preferably over the entire length of its wall internal 18. The fins 23 have a first constant radial dimension in the lower part of the heating body 6 and a second dimension constant radial, smaller than the first radial dimension, in the remaining upper part of the heating body, as shown in the figure 2. In the upper part of the heating body, where the fins 23 have their lowest radial dimension, it is thus formed a combustion 24 in which the burner 7 is located.

As shown, the burner 7, of cylindrical shape, can be by example constituted by a radiant burner of known type with low rate of Nox. However, instead of the radiant burner, one could also use other types of burners, such as a blue flame burner.

In the lower part of the heating body 6, the dimension radial of the fins 23 may for example be approximately equal to the sixth the diameter of the inner cylindrical surface of the inner wall 18 of the heating body.

Preferably, the walls 18 and 19, the longitudinal partitions 21 and the fins 23 of the heating body 6 are made in one piece, constituted for example by a profile spun from a light metal such as aluminum or an aluminum alloy. In this case, the radial dimension reduced fins 23 in the region of the combustion chamber 24 can be obtained by clipping the fins 23 for example by milling, on a length corresponding to the length of the combustion chamber 24. In in addition, the heating body 6 can be covered with a coating or anti-corrosion jacket, for example in enamel, "Teflon" or "Stainless steel" (registered names) allowing good heat exchange. The flange 5 can be constituted by an annular flange, for example aluminum or made of an aluminum alloy, which is tightly sealed, for example by welding, to the external wall 19 of the heating body 6, in the region of its lower end located outside the tank 1.

As shown in Figure 2, in the end region bottom of the heating body 6, the internal wall 18 thereof can be longer than the outer wall 19, so that a lower part of the internal wall 18 axially protrudes downwards beyond the lower end of the outer wall 19. In the case where the body double wall hollow cylindrical forming the heating body 6 is constituted by a extruded profile, this can be obtained by removing by machining, by example by milling, a lower part of the external wall 19.

A hollow annular element 25 surrounds the lower part protruding from the internal wall 18 of the heating body 6 and is fixed so waterproof, for example by welding, at the lower end of the wall internal 18 and at the lower end of external wall 19 as shown in Figure 2. The hollow annular member 25 forms both a distributor cold water and a hot water collector. For this purpose, the annular element hollow has a distributor chamber 26 which is provided with an orifice of cold water intake 27 (HEATING RETURN), and a room manifold 28, which is provided with a hot water outlet orifice 29 (HEATING START) shown only in figure 3. The orifices 27 and 29 are intended to be conventionally connected to a network not shown.

As shown in Figure 3, the distributor chamber 26 extends angularly over part of the circumference of the element hollow annular 25 and communicates with a first group of channels longitudinal contiguous 22a to 22f, at their lower ends, among the eight longitudinal channels located between the inner wall 18 and the outer wall 19 of the heating body 6. The collecting chamber 28, which is separated from the distributor chamber 26 by internal radial partitions 31 and 32 of the hollow annular element 25, extends angularly over the remaining part of the circumference of said hollow annular element and communicates with a second group of contiguous longitudinal channels, i.e. the two remaining channels 22g and 22h, at their lower ends. even though first and second groups of longitudinal channels could include the same number of channels, the first group preferably has a more channels than the second group for reasons that will be explained later.

As shown in Figure 2, at the top of the heating body 6, its internal wall 18 may be shorter than its wall outer 19, and two covers 33 and 34 are tightly fixed, by example by welding, respectively at the upper end of the wall internal 18 and at the upper end of the external wall 19. It is thus defined between the two covers 33 and 34 a passage 35 which puts the first group of longitudinal channels 22a to 22f in communication with the second group of longitudinal channels 22g and 22h.

Thus, in service, cold or lukewarm water entering the room distributor 26 through the inlet 27 is distributed in the channels 22a to 22f, flows from bottom to top in these, then in passage 35 between the two covers 33 and 34, then flows from top to bottom in the channels 22g and 22h to be collected in the collecting chamber 28 from where it leaves through the orifice 29. While the water circulates in the channels 22a to 22h, it is heated by the heat produced by the burner 7, including the gases burned are in contact with the fins 23 of the inner wall 18 of the body heating 6.

It will be noted that the fins 23 and the parts of the internal wall 18 which are located in correspondence with each of channels 22a at 22h form the first thermal bridges for direct heat exchange between the burnt gases and the water contained in said channels. Likewise, fins 23 and the parts of the internal wall 18 which are located in correspondence with the partition walls 21 between the channels 22a to 22h, as well as the partitions 21 themselves and the parts of the wall external 19 which are located in correspondence with said partitions 21 form second thermal bridges for direct heat exchange between the burnt gases and the water which is contained in the tank 1 and which is in contact with the outer surface of the outer wall 19 of the body heats 6. The parts of the external wall 19 which are located in correspondence with each of the channels 22a to 22h form thirds thermal bridges for direct heat exchange between the water contained in said channels 22a at 22h and the water contained in the tank 1. Thus, it is possible to heat both the water in the heating circuit, which circulates in channels 22a to 22h, and the sanitary water contained in tank 1 with good thermal efficiency.

Note that the passage 35 at the upper end of the body 6 is a high point in the circuit followed by the water at inside said heating body. As a result, it may happen that, during filling of the circuit with water during commissioning from the water heater or while it is in use, air bubbles gather in passage 35 and tend to stay there. It is precisely to avoid this that channels 22g and 22h form, by their number lower than that of channels 22a to 22f, a reduced flow section in order to obtain, for a given flow rate, a speed sufficient for the air bubbles possibly present in passage 35 are trapped by water in channels 22g and 22h and evacuated from the heating body 6.

As shown in Figure 2, an annular gas manifold burnt 36 is tightly fixed, for example by welding, to the lower end of the internal wall 18 of the heating body 6, at below the hollow annular element 25. The collector 36 comprises, in its periphery, the orifice 11, already mentioned above, which is connected to the pipe 12 for the evacuation of the burnt gases. The collector 36 comprises at in addition, in its lower part, an axial opening 37 which is closed with gas-tight by a removable closure plate 38, fixed to the manifold 36 by screws indicated schematically at 39 in the figure 2.

Although the hollow annular element 25 and the manifold 36 could be made up of separate pieces, they are preferably consisting of a single piece, for example a casting part or molded from a light metal such as aluminum or an aluminum alloy, which is welded to the heating body 6, as shown in Figures 1 and 2. Instead of being constituted by an annular collar fixed separately to the external wall 19 of the heating body 6, the flange 5 could be produced, if desired, in one piece with the hollow annular element 25 and the collector 36. Under these conditions, the heating body 6 forms with the flange 5, the hollow annular element 25 and the manifold 36 a first sub-assembly which can be removably attached to the tank 1, in the region of its opening 4, by means of several screws 41 represented by schematically in Figure 2.

The opening 37 of the collector 36 is intended to allow the setting in place of the burner 7 inside the heating body 6.

The closure plate 38 has a hole in its center. through which passes a tube 42, which is tightly fixed, by example by welding, in the central hole of the closing plate 38. A alternatively, the plate 38 and the tube 42 can be formed in one foundry piece. The tube 42 extends upwards inside the body of heats 6, coaxially with the internal cylindrical wall 18, as far as the lower region of the combustion chamber 24. The burner 7 is connected to the upper end of the tube 42. The lower part of the tube 42, which is located below the closure plate 38, is closed at its lower end by a plug 43 and it has, on its wall lateral cylindrical, an air intake pipe 44 which is connected detachable to the discharge port 9b of the fan 9 (see the figure 1).

Tube 8, already mentioned above, for feeding the gas burner 7, passes tightly through a central hole in the cap 43 and its upper end is provided with a nozzle or is shaped so as to form a nozzle 45 having at least one orifice outlet for injecting gas into tube 42. The part of tube 42 located between the nozzle 45 of the tube 8 and the burner 7 serves as a mixing chamber for air and gas. A static mixer of known type (not shown) can be arranged, if desired, in this part of the tube 42 in order to further improve the mixture of air and gas before their admission to the burner 7.

A sleeve 47 made of a refractory material, for example in ceramic, surrounds the tube 42 in its part located inside the body heating 6. A small radial clearance (not shown) is provided between the tube 42 and the sleeve 47 and between the latter and the crest of the fins 23 in order to hold account for different coefficients of expansion of these elements. The surface cylindrical outer surface of the sleeve 47, close to the crest of the fins 23, forces the burnt gases produced by the burner 7 to pass through the channels evacuation formed between the fins 23 and thus come into contact with the lateral surfaces of the fins 23 to transmit their heat to them. Although the lower end of the refractory sleeve 47 is shown in Figure 2 at about the same level as the end bottom of the internal wall 18 of the heating body 6, the sleeve refractory 47 could extend down to the cover plate 38.

In Figure 2, reference numbers 48 and 49 denote electrodes for igniting the burner 7. These electrodes 48 and 49 can be conventional spark type ignition electrodes or of the incandescent type. In known manner, the burner 7 can be also associated with a flame control electrode (not shown). The above-mentioned electrodes are electrically connected to a unit conventional control and monitoring of the water heater by conductors electrical such as conductor 51 shown in figure 2. The conductor 51 passes through an insulating sheath 52, for example in soapstone, passing through sealingly the closure plate 38 and passing through a channel longitudinal formed in the refractory sleeve 47.

It will be noted that the plate 38, the tube 42, the sleeve 47, the burner 7 and the electrodes associated with the burner form a second sub-assembly which, by unscrewing the screws 39, can be separated from the first sub-assembly formed by elements 5, 6, 25 and 36, thus allowing a inspection and cleaning of the interior of the heating body 6, of the burner 7 and associated electrodes, as well as, if necessary, a replacement of the burner and / or the electrodes.

The water heater can be installed from so that, in service, the opening 4 of the reservoir 1 is not at the bottom of the tank, but at the top or on one side of it. Furthermore, in the region of passage 35, the walls 18 and 19 may have the same length; the covers 33 and 34 may have a form and a mode of different fixing than those shown in figure 2, provided that a passage is provided between them to put the channels 22a to 22f in communication with channels 22g and 22h.

On the other hand, the shape and position of the gas injection tube 8 may be different from those shown in Figure 2; through example, the tube 8 can be arranged so as to inject the gas transversely in the tube 42 or in the fitting 44. In addition, instead inject gas downstream of fan 9, it can also be injected from known way upstream of the fan 9. As is also the case known, the fan 9 can be connected not upstream of the burner 7, but downstream of it, for example between the orifice 11 and the tube 12 or at the outlet of the latter, so as to function as a smoke extractor.

In in the latter case, line 13 is to be connected to tube 42.

Claims (10)

1. A gas water heater, comprising a water tank (1) fitted with an inlet tube (2) for cold water to be used for sanitary purposes and an outlet tube (3) for hot water to be used for sanitary purposes, a gas burner (7), means (8, 9, 42) of delivering a combustible air/gas mixture to the burner (7), and a heating body (6) which is hollow and elongated in form and engages with the interior of the tank (1) via a single opening in the said tank and which is fitted with a single flange (5) by means of which it is fixed to the tank (1) and which obturates, in a watertight manner, the opening (4) of the said tank, the said heating body (6) containing a combustion chamber (24) in which the burner (7) is placed and a drainage conduit for the burnt gases linking the said combustion chamber (24) to an outlet (11) for the burnt gases envisaged at one end of the heating body (6) situated outside the tank (1), characterised by the fact that the said heating body (6) also contains at least a first conduit (22c) and at least a second conduit (22h) which extend from the said end of the heating body (6) situated outside the tank (1) to an opposite end of the heating body situated inside the tank, the said first and second conduits being connected via a passage (35) formed within the said opposite end of the heating body (6), and connected respectively with a cold water inlet orifice (27) and a hot water outlet orifice (29), which are envisaged at the end of the heating body (6) situated outside the tank (1) and can be attached to a heating water circuit and by the fact that the heating body (6) has the general form of a hollow cylinder with double walls, comprising an internal cylindrical wall (18) and an external cylindrical wall (19), with several longitudinal partitions (21) which extend radially between the internal and external walls and which define several longitudinal conduits (22a to 22h) laid out around the circumference in relation to the axis of the cylinder of the heating body (6).
2. A gas water heater according to claim 1, characterised by the fact that a hollow annular element (25) forming a distributor for the cold water and hot water collector is fixed, in a watertight manner, to the said internal and external walls (18, 19) at on end of the heating body (6) situated outside the tank (1), the said hollow annular element (25), comprising a distributing chamber (26) which extends, in an angular way, over a part of the circumference of the said annular element, is fitted with the said cold water inlet orifice (27) and connects with a first group of contiguous longitudinal conduits (22a to 22f) from among the said longitudinal conduits, at their lower ends, and a collecting chamber (28), which extends in an angular way over the remaining part of the circumference of the hollow annular element (25), remaining completely separated from the distributing chamber (26), is fitted with the said hot water outlet orifice (29) and is connected with a second group of contiguous longitudinal conduits (22g, 22h) among the said longitudinal conduits, at their lower ends.
3. A gas water heater according to claim 2, characterised by the fact that, at the end of the heating body (6) situated inside the tank (1), a first and second cover (33 and 34) are fixed, in a watertight manner, respectively, to the internal wall (18) and the external wall (19) of the heating body and define, between them, the said passage (35) which connects the longitudinal conduits (22a to 22f) in the first group with the longitudinal conduits (22g to 22h) in the second group.
4. A gas water heater according to any of claims 1 to 3, characterised by the fact that several blades or longitudinal ribs (23) are raised up along the internal surface of the internal wall (18) of the heating body (6) and extend longitudinally along at least a part of the axial length of the said heating body (6).
5. A gas water heater according to claim 4, characterised by the fact that the blades or ribs (23) extend along the whole length of the internal wall (18) of the heating body (6) and have a first constant radial dimension in a first part of the heating body (6) which is adjacent to its end situated outside the tank (1), and a second constant radial dimension, which is smaller than the first radial dimension, in a second part of the heating body which is adjacent to its end situated inside the tank (1), the said combustion chamber (24) being situated in the second part of the heating body (6), where the blades or ribs (23) have the second said radial dimension.
6. A gas water heater according to any of claims 2 to 5, characterised by the fact that a collector for the burnt gases (36) is fixed, in a watertight manner, to the internal wall (18) of the heating body (6), at the end of the said heating body, situated outside the tank (1), and comprising, in its peripheral part, the said outlet (11) for the burnt gases and, in its lower part, an axial opening (37) which is obstructed, in a watertight manner, to the gases by means of a moveable closure plate (38).
7. A gas water heater according to claim 6, characterised by the fact that means (8 9, 42) which deliver the combustible air/gas mixture to the burner (7) comprise a tube (42) which passes through the said closure plate (38) and extends coaxially to the interior of the heating body (6) to the combustion chamber (24), where the tube (42) is connected to the burner (7).
8. A gas water heater according to claim 7, characterised by the fact that the part of the tube (42) which is situated between the closure plate (38) and the burner (7) is surrounded, along at least one part of its length, by a mantle (47) made of a refractory material whose external cylindrical surface is near the top of the blades or ribs (23).
9. A gas water heater according to claims 2 to 6, characterised by the fact that the heating body (6) is constituted of a profile section bar made of a lightweight metal such as aluminium or an aluminium alloy, and that the said hollow annular element (25) and the said burnt gases collector (36) are constituted of a single smelted piece, either cast or moulded, made of a lightweight metal such as aluminium or an aluminium alloy, which is fixed by soldering onto the heating body (6).
10. A gas water heater according to claim 2, wherein the number of longitudinal conduits (22a to 22f) in the first group is greater than the number of longitudinal conduits (22g to 22h) in the second group.

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