The invention relates to a heating system comprising an enclosure in which there is an air circuit, the said heating system allowing the heating of the air external to the enclosure and of a liquid, the said air circuit incorporating:

• a heating body,
• a heat exchanger suited to the exchange of heat between the air of the air circuit and the liquid,
• forced-circulation means allowing a forced circulation of air in the air circuit,

The invention also relates to a method of heating air and a liquid, the said heating method using a heating system according to the invention.

Heating systems such as wood-burning stoves, gas-fired space heaters and charcoal heaters are very widespread. In general, these systems are used to heat the room in which they are located, chiefly by radiation and by convection. Wood-burning stoves additionally capable of producing hot water also exist. In these, it is known practice to have a hot water circuit that is independent of and external to the heating body of the heating system, so as to avoid any corrosion problems.

Document EP0332039 describes such a heating system that allows the heating both of the air surrounding an enclosure containing the heating body of the heating system and of water. In this system, an air/water heat exchanger for heating the water is placed inside the enclosure without being in contact with the heating body. The enclosure of the system described in document EP0332039 comprises two hot air circuits I and II, circuit I being in direct contact with the heating body. In a hot water production mode, a fan is switched on to draw hot air through the air/water heat exchanger. The switching-on of the fan also causes the opening of a shutter that allows the air to circulate in the closed circuit I. In this mode, the transmission of heat from circuit I to circuit II is possible only via a wall that separates these two circuits. The hot air that heats the water therefore circulates in a closed circuit in circuit I in the hot water production mode. In a hot air production mode, the fan is switched off and the abovementioned shutter is closed. By contrast, two other shutters are then opened to allow increased heat transfer between air circuits I and II. Finally, two openings respectively capture the cooler air surrounding the enclosure of the heating system and discharge the hot air out of the enclosure in the hot air production mode.

In the latter mode, the transmission of heat to the outside of the enclosure is afforded by natural convection because the fan is switched off. At the same time, the cool external air entering via the openings into circuit I has to pass through the air/water heat exchanger to come into contact with the heating body, thus cooling the water circuit. Such a system additionally entails the presence of various shutters within the enclosure of the heating system. Such elements that are not accessible from the outside are not easy to replace or to service. Finally, such a system proposes two exclusive modes of operation: air heating or water heating.

It is one of the objects of the present invention to provide a heating system that allows the heating both of the air surrounding the heating system and of a liquid while at the same time reducing the extent to which the liquid is cooled by the air external to the heating system when heating of this external air is desired. To this end, the heating system according to the invention is characterized in that:

• the first opening is situated between the heating body and the heat exchanger along the air circuit,
• the second opening is situated between the heat exchanger and the forced-circulation means along the air circuit.

When heating the air external to the enclosure, the first and second openings are at least partially open. Air external to the enclosure enters the latter via one opening and is heated up upon contact with the heating body. For the most part, the heated air emerges from the enclosure via the other opening. Given the position of the two openings the amount of air passing through the heat exchanger in this embodiment is small and therefore the cooling of the liquid by the air external to the enclosure is likewise reduced.

The heating system according to the invention is preferably characterized in that when the system is in operation, the forced-circulation means are in operation when the first and second openings are at least partially open. The forced-circulation means therefore ensure forced air convection when the openings are at least partially open, making it possible to increase the power for heating the air external to the enclosure by comparison with the existing systems.

The heating system of the invention is preferably characterized in that the heat exchanger is situated underneath the heating body. Thus, the air heated by the heating body and which is directed towards the upper interior part of the enclosure by natural convection will have little heating effect on the liquid passing through the exchanger. This is because cold air naturally positions itself underneath the hot air. Such a preferred embodiment thus allows one to limit any overheating of the liquid in the event of unwanted shutdown of the forced-circulation means and/or unwanted closure of the openings.

The heating system of the invention is preferably characterized in that the first and second openings are not at the same height, and in that the air external to the enclosure enters the inside of the enclosure through the lowermost opening and re-emerges therefrom via the uppermost opening. Such a preferred embodiment encourages, when the air external to the enclosure is being heated, the transfer of cold air rather than of hot air from the outside of the enclosure to the inside. This is because the lower down it is situated, the colder is the air external to the enclosure.

The heating system is preferably characterized in that:

• the enclosure has two opposite lateral faces,
• the first opening is situated on one of the said lateral faces of the enclosure,
• the second opening is situated on the other of the said lateral faces of the enclosure.

Thus, the streams of air entering and leaving the enclosure are advantageously isolated from one another, thereby reducing the mixing between the incoming cold air and the outgoing hot air when heating of the air external to the enclosure is desired.

The heating system is preferably characterized in that:

• the enclosure comprises a front face,
• the first and second openings are situated on the said front face of the enclosure.

It is another object of the invention to provide a method that allows the obtention of hybrid operating modes other than the two exclusive modes of operation that are heating the air external to the enclosure and heating the water. To achieve this, another aspect of the invention relates to a heating method using a heating system as described in the preceding paragraphs, the said method comprising one of the following two steps:

• actuating the shut-off means in the direction of increasing the size of the openings when the ratio between the power used to heat the air external to the enclosure and the power used to heat the liquid is to be increased,
• actuating the shut-off means in the direction of reducing the size of the openings when the ratio between the power used to heat the air external to the enclosure and the power used to heat the liquid is to be reduced.

These aspects of the invention together with others will be clarified in the detailed description of some specific embodiments of the invention, reference being made to the figures in which:

Figure 1

schematically shows the principle of the heating system of the invention when the openings are closed;

Figure 2

schematically shows the principle of the heating system of the invention when the openings are open;

Figure 3

shows a perspective view of one embodiment of the heating system according to the invention;

Figure 4

is a view in section parallel to the front face of the heating system of Figure 3;

Figure 5

is a view in section parallel to the lateral faces of the heating system of Figure 3;

Figure 6

shows three positions of the shut-off means with respect to the openings of the enclosure of the heating system.

The general principle of the heating system 10 according to the invention is illustrated in Figures 1 and 2. With reference to these figures, the heating system 10 comprises an enclosure 15. The enclosure 15 is designed to form within it an air circuit. In this air circuit there are a heating body 20, forced-circulation means 70 and a heat exchanger 30.

The heating body 20 represents the heat source of the heating system 10. The heating body 20 is typically in the form of a cavity into which a fuel (wood being one example of this) can be introduced and from which the flue gases emerge via a pipe that has not been depicted in Figures 1 and 2.

The heating system 10 is typically located in a room 110 that is to be heated by heating the air external and adjacent to the enclosure 15. The heating system 10 is also capable of heating a liquid such as water. The heat exchanger 30 is used to heat the liquid and is typically provided with a cold water inlet 90 and with a hot water outlet 100. This inlet and outlet can be connected to a central heating circuit or to a primary circuit for heating a reserve of water contained for example in a boiler. A pump may be used to ensure that the liquid circulates correctly through the heat exchanger 30.

The enclosure 15 comprises at least a first and a second opening 40. Each of the openings 40 is equipped with shut-off means 80 allowing it to be completely or partially closed off. As illustrated in Figure 2, one example of shut-off means 80 is a shutter capable of completely covering an opening 40.

Forced-circulation means 70 are able to ensure forced circulation of air inside the enclosure 15. One example of forced-circulation means is a turbine fan.

When rapid heating of the liquid is required, the openings 40 are preferably completely shut off by the shut-off means 80 and the forced-air-circulation means 70 are preferably in operation: the air heated up by the heating body 20 then circulates in a closed circuit through the enclosure 15. This situation is illustrated in Figure 1 where the arrows indicate one possible direction of circulation of air through the enclosure 15 in a closed circuit. The forced-circulation means 70 can be mounted in a direction such that they cause the air to flow in the opposite direction to the one illustrated in Figure 1.

Figure 2 shows the heating system 10 of the invention when heating of the air external to the enclosure 15 is required. In this case, the two openings 40 allowing communication between the air external to the enclosure 15 and the air circuit are at least partially open. The position of the openings 40 makes it possible to obtain an air circuit adjacent to the heating body 20 while at the same time reducing the flow of air passing through the heat exchanger 30. This property is illustrated in Figure 2 using the difference in thickness of the arrows representing the different air flows. More specifically, a first opening 40 needs to be situated between the heating body 20 and the heat exchanger 30 along the air circuit and a second opening 40 needs to be situated between the heat exchanger 30 and the forced-circulation means 70 along the air circuit. The pressure drops at the heat exchanger 30 have preferably to be greater than those at the openings 40 when these openings are at least partially open in order therefore to allow the air flow through the openings 40 to be greater than the air flow through the heat exchanger 30. For preference, the forced-circulation means 70 are also in operation when the openings are at least partially open.

One particular embodiment of the invention is illustrated in Figure 3. In this case, the enclosure 15 of the heating system 10 is typically that of a wood-burning stove or of a charcoal heater located in a room 110 that is to be heated.

In this embodiment, it is generally possible to access the heating body 20 from the front face 150 of the enclosure 15 via a glazed door. The front face 150 of the enclosure 15 is the face represented furthest forward in Figure 3. The enclosure 15 of the heating system 10 of Figure 3 also comprises two opposite lateral faces 151 and 152 which are perpendicular to the front face 150. The front face 150 and the two lateral faces 151 and 152 are indicated in Figures 4 and 5 which are, respectively, a section parallel to the front face 150 and a section parallel to the lateral faces 151 and 152 of the heating system of Figure 3. The flue gases are typically removed from the heating body 20 via a pipe connected to a chimney. This pipe has not been depicted in Figures 3 to 5 for reasons of clarity and is generally situated at the rear (the face opposite the front face 150 of the enclosure 15) or on top of the enclosure 15.

As illustrated in Figures 3 to 5, the heat exchanger 30 is preferably situated underneath the heating body 20. Likewise, a first opening 40 is situated above the heat exchanger 30, whereas a second opening 40 is situated underneath the heat exchanger 30. When heating of the air external to the enclosure 15 is required, the air external to the enclosure 15 typically enters via the opening 40 situated underneath the heat exchanger 30 and re-emerges via the opening situated above the heat exchanger 30, thanks to the action of the forced-circulation means 70 which may be a fan. The fact that the second opening 40 is situated underneath the first opening 40 means that colder air can be drawn into the enclosure 15. A flow of air in the other direction is possible if the fan 70 forces air to flow in the other direction.

In one embodiment as shown in Figures 3 to 5, the enclosure 15 comprises two opposite lateral faces 151 and 152. In order to reduce the mixing between the cold air entering the enclosure 15 and the hot air leaving the enclosure 15, it is preferable for each of the two openings 40 to be positioned one on each of the two opposite lateral faces, as has been illustrated in Figure 3.

For ease of access to the openings 40, particularly when the enclosure 15 is built into a wall, it is preferable for the first and second openings 40 to be positioned on the front face 150 of the enclosure 15. The front face 150 of the enclosure 15 is the face depicted furthest forwards in Figure 3.

When rapid heating of the liquid is required, it is preferable for the openings 40 to be completely shut off using the shut-off means 80. When rapid heating of the air external to the enclosure 15 is required, it is preferable for the openings 40 to be completely opened and for the forced-circulation means 70 to be actuated. The air conveyed by the forced-circulation means 70 can then enter via one of the openings 40 and re-emerge via the other, the flow of air passing through the heat exchanger 30 being reduced.

In some instances it may be advantageous to heat both the air external to the enclosure 15 and the liquid passing through the heat exchanger 30. Typically, the openings 40 are then only partially shut off by the shut-off means 80. The ratio between the power used for heating the air external to the enclosure 15 and the power used for heating the liquid can be modified by changing the percentage used closure of the openings 40 by the shut-off means 80. If it is desirable for the liquid to be heated more rapidly, then the openings 40 are shut off further. If it is desirable to heat the air external to the enclosure 15 more rapidly, then the openings 40 are opened wider. The size of the two openings 40 is preferably modified by the shut-off means in the same manner.

Figure 6 shows three possible configurations of the shut-off means 80 when the latter are in the form of a square plate and the openings 40 are in the form of a circle. In scenario (a) of Figure 6, the shut-off plate 80 does not cover the opening 40 at all and this opening is therefore wide open (maximum heating of external air). In scenario (b), the shut-off plate 80 partially covers the opening 40 (mixed heating of the air external to the enclosure and of the liquid), whereas scenario (c) corresponds to the configuration in which the opening 40 is completely shut off (maximum heating of the liquid). The shut-off plate 80 can be moved manually or by an electric motor for example.

The enclosure 15 may comprise more than two openings 40. However, at least one first opening 40 needs to be situated between the heating body 20 and the heat exchanger 30 along the air circuit while at least one second opening 40 needs to be situated between the heat exchanger 30 and the forced-air-circulation means 70 along the air circuit. Likewise, it may be preferable to use several fans 70 rather than just one, for space and/or noise reasons. The enclosure 15 may comprise more than one heating body 20 to increase the heating power of the heating system 10 and more than one heat exchanger 30 to allow more than one liquid to be heated.

The present invention has been described in conjunction with some specific embodiments which are purely illustrative and must not be considered to be limiting. In general, the present invention is not restricted to the examples illustrated and/or described hereinabove. The use of the verbs "comprise", "include" and so on or any other variant or conjugation thereof does not in any way exclude the presence of elements other than those mentioned. The use of the indefinite article "one", "a", "an" or of the definite article "the" when introducing an element does not exclude there being a plurality of such elements.

To sum up, the invention can also be described as follows. Heating system 10 comprising an enclosure 15, the said heating system 10 allowing the heating of the air external to the enclosure 15 and at least one liquid. The enclosure 15 incorporates at least one heating body 20, at least one heat exchanger 30 and forced-circulation means 70. There is an air circuit within the enclosure 15. The enclosure 15 comprises at least two openings 40 of which the positions with respect to the other elements make it possible, when heating the air external to the enclosure 15, to reduce the flow of air passing through the heat exchanger 30 while keeping the forced-circulation means 70 in operation.