The present invention relates to improvements in heating apparatus.

In heating appliances, particularly for heating dwellings and the like, a reservoir is usually incorporated for temporary storage of so-called heated tap water, so that the user has hot water immediately available as soon as he/she opens a hot water tap.

Such a combi-appliance with a power of for instance 22-24 kW must be able to provide for instance 6 litres of water per minute at 60°C from such a storage tank.

The appliances are found in practice to be unable to meet this requirement, particularly when the burner of such a heated appliance is not actuated or is actuated to a lesser extent (in modulating operation) for heating fluid in pipes and radiators of the heating appliance in the dwelling, for instance in the summer.

In the non-prepublished international patent application PCT/EP97/06179 is described a storage tank which technically satisfies the above stated requirements but which has been found in practice too expensive to manufacture.

According to a first aspect the present invention provides a device for storing and/or heating fluid, comprising: -an outer jacket; -an inner jacket arranged in the interior of the outer jacket; and -an intermediate jacket arranged between the outer jacket and inner jacket which is formed and arranged between the inner jacket and the outer jacket

such that channels are formed in the intermediate space between inner and outer jacket in which fluid for heating and heating fluid can be fed through such that heat exchange takes place between these two fluids.

Two helical channels are preferably formed through the intermediate jacket so that after arranging of the intermediate jacket between the inner and outer jacket no further actions have to be performed to obtain heat exchange between the two fluids.

In a further preferred embodiment the intermediate jacket is welded and/or soldered fixedly to the inner and outer jacket, which can be realized easily and at little cost.

The present invention further provides a method for manufacturing a device for storing and/or heating fluid, comprising the following steps of: -providing a substantially cylindrical inner jacket and a substantially cylindrical outer jacket; -preforming an intermediate jacket; and -arranging the intermediate jacket between the inner and outer jacket in a manner such that two helical channels in heat-exchanging relation are formed therebetween.

In heating appliances, particularly for heating dwellings and the like, a vent is usually incorporated for venting air bubbles which have formed in the central heating water. If venting is insufficient, problems occur in respect of the efficiency of heating of the central heating water.

In the non-prepublished international patent application PCT/EP97/06179 is described a so-called combi-appliance with compact dimensions and high efficiency. The efficiency of such a combi-appliance can however be unfavourably affected by inadequate venting.

According to a second aspect the present invention provides a device for discharging gaseous medium from a fluid flow, comprising:

-a first channel for fluid possibly provided with gaseous medium; -a secondary channel which extends substantially in the direction opposed to the first channel and which debouches close to a secondary inlet of the first channel.

The gas bubbles can escape in the direction of the vent through the secondary channel. Via the secondary inlet of the first channel and owing to the venturi action, the fluid possibly carried along in the direction of the vent is then entrained once again in the main flow of the fluid.

In a first preferred embodiment the venturi action in the channel is also brought about by a deflecting member whereby the fluid flow is deflected.

In order to influence the flow such that gas bubbles can escape easily, the device according to the present invention is preferably provided in a second preferred embodiment with a fluid forcing means behind which a suction conduit of a pump of standard make is preferably arranged.

Further advantages, features and details of the present invention will be described on the basis of the following description of preferred embodiments thereof with reference to the annexed drawing, in which: fig. 1 shows a front view, partly in cross- section, of a combi-appliance, wherein a device according to the present invention can be applied; fig. 2 shows a view in cross-section of a preferred embodiment of a device according to the present invention; and fig. 3 is a partly broken away view in perspective of another preferred embodiment of a device according to the present invention.

An example of a combi-appliance 10, wherein a device according to the present invention can be applied, comprises a burner construction 12 in which a mixing chamber 12 is placed for mixing air and fuel, in the

present case natural gas. On the top the appliance 10 is provided with a feed and discharge 16 respectively 18 for supplying air and discharging the combustion gases. On the underside the appliance is provided with connections 20,22,24,26 and 28 for supply of gas, feeding and draining of water for the heating system and feeding and draining of water for heated tap water.

A heat exchanger 30 is further arranged in appliance 10 in addition to a three-way valve 32 for switching between supply of tap water and supply of water for the central heating installation under the control of a central control unit. Arranged round the burner construction in this preferred embodiment is a double- walled, helical tube 34 in which are guided both the central heating water for heating and the tap water for heating.

Instead of being provided with heat exchanger 30 the appliance of fig. 1, concerning which further information can be found in the above mentioned non- prepublished international patent application and which has compact dimensions, can be provided with a preferred embodiment of a reservoir 40 which, because of its compact size, can be placed in appliance 10 to replace heat exchanger 30. Reservoir 40 comprises a substantially cylindrical outer jacket 41, for instance of metal such as stainless steel, having placed therein a substantially cylindrical inner jacket 42, likewise preferably of metal such as stainless steel.

Outer jacket 41 and inner jacket 42 are mutually connected via an intermediate jacket 43 which is formed helically and is welded or soldered fixedly (in substantially watertight manner) to both the inner jacket and the outer jacket.

On the underside the reservoir 40 is provided with a feed stub 44 for supply of tap water for heating, which connecting stub 44 debouches into the interior of inner jacket 42, which is open at the top.

A connecting stub 45 is further provided for draining heated tap water. Close to the underside a connecting stub 46 is further arranged for heated central heating water which is supplied as according to arrow A and which via a helical channel is urged upward between outer jacket 41 and intermediate jacket 43 as far as connecting stub 47 on the top part of reservoir 40. The tap water for heating or keeping hot is first urged upward as according to arrows B and then guided downward in counterflow along a helical channel into connecting stub 45.

A temperature sensor 48 is further arranged in the bottom of reservoir 40 to sense the temperature of the water in the interior of inner jacket 42.

If temperature sensor 48 senses that the water in the reservoir has reached the temperature of a predetermined value, such as 60 or 70°C, the burner of the appliance can be set into operation in a manner not shown, central heating water can be heated and three-way valve 32 of fig. 1 placed in a position such that the heated central heating water is not carried out of appliance 10 but is fed back to the heat exchanger around the burner. After a time the tap water will thus once again have reached the desired temperature.

In the appliance of fig. 1 a flow element 60 (fig. 3) can be applied. Arranged in housing 62 thereof is a discharge conduit 64 for discharge of air and connection to a vent (not shown) in addition to a feed conduit 66 for feeding central heating water supplied as according to arrow A, in which air bubbles may be present. Further connected to housing 62 is a pump 68, for instance of standard make, with a suction conduit 70 and a pressure conduit 72.

The central heating water supplied via connection 66 is deflected downward as according to arrow B by a deflecting plate 73 into a channel 74 which debouches close to a horseshoe-shaped fluid forcing plate 76, behind which is connected suction conduit 70 of pump

68. The supplied central heating water is deflected as according to arrows C by the horseshoe-shaped fluid forcing plate 76 and further guided therebehind into pump 68. Arranged between a rear wall 75 and the outlet 78 of channel 74 is an intermediate space 80 along which the air bubbles in the central heating water, as well as co- displaced water, move upward as according to arrow D as far as an outlet 82 of channel 74, which is situated behind deflecting plate 73 and through which the co- displaced central heating water is once again guided by the underpressure behind deflecting plate 73 downward into channel 74 as according to arrow E, while the air bubbles are discharged to the vent as according to arrow F.

The central heating water with air bubbles removed is thus pressed via arrow G out of pump 78, whereafter it is discharged via arrow H from venting element 60.

During tests of the above described preferred embodiment, wherein said rear wall was give a transparent form, it was found that 98% of the air bubbles with a diameter of < 1 mm introduced artificially into a liquid flow at for instance 1 Bar pressure leave the water flow via the vent. The above described preferred embodiment of a device according to the present invention also exhibits a low start-up resistance, while the pressure generated by a pump is not adversely affected, or hardly so.

Finally, the above described preferred embodiment can be realized in extremely compact and structurally elegant manner with few components.

The present invention is not limited to the above described preferred embodiment; the rights sought are defined by the following claims, within the scope of which many modifications can be envisaged.