HEATING DEVICE FOR A SAUNA

Abstract: Sauna with heating device comprising a container (5) with stones (6), a heating element (4) for heating said stones and a tube (7) for evaporating liquid which tube (7) has outlet openings (9) for vapour in its top surface and is connected to a liquid circulating conduit system (11) from which liquid portions can be allowed to enter the tube and evaporate.

Description: The invention relates to a heating device for a sauna, comprising a sauna stove which can be set up in free-standing fashion in the sauna room and is provided with a container having ceramic, heat-accumulating material, such as stones, and with a heating system, which heats this material and with an evaporation device. A device of this type is known from DE-A-3404 892. This known heating device has a heating system below the container for ceramic material and a further heating system inside a liquid container below the first mentioned heating system. In said lower heating system, the liquid can be evaporated which liquid then evaporates so that the steam generated by said evaporation flows upwardly through the ceramic material and passes the first mentioned dry heating system. In the use of sauna it often is desirable to make use of fresh evaporation of liquid. This is done by throwing water on the hot stones. If this is done with the above-mentioned known device, non-evaporated water comes in contact with the heating system immediately below the stones and this reduces the life time of the heating system. Moreover, the stones which suddenly are brought into contact with cool liquid are subjected to erosion as well and have to be replaced of the some time of use. Since these stones have to be of a special quality, this replacement incurs high costs, particularly in greatly used saunas. Moreover, the electric heating elements which are underneath the stones are also greatly exposed to sudden cooling if unevaporated water leaking through the stones reaches them. Frequent replacement is in that case necessary. The object of the invention is to obtain a heating device for a sauna in which the stones and the heating elements are not exposed to great erosion in case fresh evaporation is required. This object is achieved according to the invention in that the evaporation device is a horizontal pipe which is inside the heating system of the sauna stove, said heating system being in or underneath the container with ceramic material which pipe is heated by the heating system of the stove and comprises holes in the upper surface thereof for steam to be expelled and said pipe is connected via a connection line to a liquid supply circuit. The liquid now evaporates to steam in the heated evaporation pipe. Such an evaporation pipe, which is, for example, of metal, can withstand better than the stones the cooling which always occurs through the introduction of liquid. Moreover, it can be much cheaper than the stones and is simple to replace, should it ever fail. The steam emerging from the evaporation pipe is at a much higher temperature than the liquid introduced. The steam then comes into contact with the hot stones and is thereby heated further to produce the desired effect of a steam surge in the sauna. Of course, the erosion of the stones, if present at all, is much less than if the liquid were to be sprinkled directly onto the stones. A pipe for evaporation of a liquid is known per se from NL-C-162302. This known tube is used in heating elements located in a special, separate heating room of the sauna, in which there are no stones. The disadvantage of this design is that the combination of pipe and heating element produces only a slight heat-accumulating effect, so that the temperature cannot be held entirely constant on evaporation of the liquid. The steam output is also thereby adversely affected. This known device is therefore not suitable either for keeping the temperature in the sauna constant on evaporation of the liquid or for producing a suitable steam output, such as is possible with the heating device according to the invention. The circuit for the infeed of the liquid can be designed in various ways. A very simple design is a circuit comprising a line connected to the evaporation pipe having at its free end a suitable opening for pouring in the liquid. It can, however, happen here that introducing too much mixture into the pipe causes the latter to cool down too much, with the result that in the end liquid mixture, rather than steam, emerges from the discharge holes. In order to avoid this, in a preferred embodiment the heating device according to the invention is designed in such a way that the liquid circuit is a closed circuit having a supply or mixture tank and a lone loop with pump which ensures continuous circulation, said line loop being provided with a branch line to the evaporation pipe, and with a valve whose throughflow time and/or quantity is adjustable. The continuous circulation of the liquid has the effect that said liquid is directly available for infeed to the evaporation pipe once the valve opens. Furthermore, this circulation ensures constant mixing of the liquid with the aromatic substances to be added thereto in the tank. The valve here can, for example, be set in such a way that the liquid is fed in continuously in such low quantities that the evaporation pipe does not cool down too much and does not overflow. The valve can also be designed in such a way that it always remains open only for a short time, so that it has to be operated again to obtain a new quantity of liquid. In this latter case the heating device is preferably designed in such a way that the valve is provided with a regulating element which can be operated for opening of the valve and has a setting facility for the period of time that the valve is open, and the regulating element also has a setting facility for the period of time, following the period that the value is open, that the operating mechanism of the regulating element is switched off. The users of the sauna can now operate the valve as desired by, for example, pressing an operating button provided in the sauna. By making a suitable selection of the time duration and that during which the valve on operation remains open or subsequently must remain closed, it is possible to avoid too much liquid being introduced or too much steam being formed. Finally, the liquid can also be introduced fully automatically at certain intervals. In that case, just as in the case of continuous infeed, the heating device need not be operated to obtain steam. It is, however, possible with infeed at intervals to give steam surges, something which is not the case with continuous infeed. The above-mentioned automatic regulations for liquid infeed are in particular attractive for public saunas. In such saunas an individual setting of the steam development is not so desirable, while personnel are not always available for the operation. It is also important here that there can be a considerable saving on the quantities of liquid used, while the correct quantities of steam are still produced. The latter is also important for health reasons, since too great a steam development could make the humidity too high and the oxygen content could fall too much. In connection with saving space, the liquid circuit can be placed outside the sauna cubicle, the branch pipe being conveyed through the wall of the sauna cubicle to the sauna stove. Through the continuous circulation, any volatile oil, such as eucalyptus oil, added to the water remains mixed with the water, so that the infeed of the correct mixture is ensured at all times. If this mixture were to lie in such a circuit, considerable concentration differences would in fact occur through separation. Consequently, mainly water or mainly eucalyptus oil would be fed to the evaporation pipe. Another advantage is that the eucalyptus oil can be mixed directly with the water without the differences in viscosity giving rise to problems. With infeed systems known hitherto for a mixture of water and eucalyptus oil, working according to the venturi effect, it was necessary to use a mixture of alcohol and eucalyptus oil in order to permit suction of this mixture along with the transporting liquid. However, in order to obtain the venturi effect, a quantity of liquid which is found to be too great for reasonable steam development must be transported, which entails the above-mentioned disadvantages of excessive cooling of the stones, excessive consumption, a health risk and the like. Another favourable effect of the circuit used according to the invention is that the eucalyptus oil does not evaporate quickly from it, on account of both the forced mixing with water during circulation and the fact that the circuit is completely closed. The invention will now be explained with reference to the drawing. Fig. 1 shows a partially cutaway sauna with the heating device partially in longitudinal section. Fig. 2 shows the heating device in cross section. The sauna cubicle 2, which is accessible through door 1, contains a sauna stove 3, provided with heating elements 4 and a container 5 having stones 6. The evaporation pipe 7, which has a feed line 8 for the liquid to be evaporated and also steam discharge holes 9, is also provided underneath the container 5 for the stones 6, and is surrounded by the heating elements 4. The liquid is fed in through a regulating valve 10 from the liquid circuit 11, which is connected at both ends to the liquid supply tank 12. The liquid is continuously circulated by means of a pump 13, so that the correct mixture of, for example, water and eucalyptus oil is always present at the valve 10. The valve 10 can feed in the correct quantity of liquid fully automatically to the evaporation pipe 7, or can be operated from the sauna cubicle 2 by operating means which are not shown. The pipe 7 can also be provided between the stones.

Claims: Heating device for a sauna, comprising a sauna stove (3) which can be set up in free-standing fashion in the sauna room and is provided with a container (5) having ceramic, heat-accumulating material, such as stones (6), and with a heating system (4), which heats this material (6) and with an evaporation device characterized in that , the evaporation device is a horizontal pipe (7) which is inside the heating system (4) of the sauna stove (3), said heating system (4) being in or underneath the container (5) with ceramic material (6), which pipe (7) is heated by the heating system (4) of the stove (3) and comprises holes (9) in the upper surface thereof for steam to be expelled and said pipe (7) is connected via a connection line (8) to a liquid supply circuit (11). Heating device according to claim 1, characterized in that the liquid circuit (11) is a close circuit having a supply or mixture tank (12) and a line loop (11) with pump (13) which ensures continuous circulation, said line loop (11) being provided with a branch line (8) to the evaporation pipe (7) and with a valve (10) whose throughflow time and/or quantity is adjustable. Heating device according to claim 2, characterized in that the valve (10) is provided with a regulating element which can be operated for opening of the valve (10) and has a setting facility for the duration of time that the valve (10) is open, and the regulating element also has a setting facility for the duration of time, following the period that the valve is open, that the operating mechanism of the regulating element is switched off.

Inventors: BEEN, DIRK
Applicants: BEEN, DIRK
Application year: 1987
Main classification: A61H33
IPC codes: A61H33