TECHNICAL FIELD This invention concerns a single or double sauna cabin using hot water from the domestic water system.

BACKGROUND ART It is known that the word"sauna"refers not only to the typical Finnish sauna characterised by high temperatures (about 80° C) and low humidity (about 20%), but to any environment with moderately hot temperatures (about 40° C) and high humidity (up to 100%). In other words here "sauna"means a physical environment similar to thermal baths or Turkish baths. This is an environment offering a comfortable relaxing sensation produced by a moderately hot environment saturated with humidity. This kind of environment is increasingly in demand both in luxurious hotels wanting to offer their customers ever more exclusive and refined facilities and by private users. The financial wellbeing of ever wider bands of society has tended to transform the old bath room into a sophisticated space offering a comfortable and relaxing interlude in which to unwind after a stressful day's work. This has led to the production of cabins offering the consumer the comfort and pleasures of a"sauna"in the intimate and

private atmosphere of his own home. As these sauna cabins are closed spaces, they are most easily built inside existing shower boxes and the original objective was to find a way of using the shower boxes for the introduction of warmth, and in particular warm steam. For this reason, "shower-sauna"cabins are available on the market based on two basic designs, the first of which consists of nozzles spraying very hot water (about 80° C) against areas at the bottom of the cabin. This favours water nebulisation and thus saturates the upper part of the cabin with steam generated by the spontaneous rise of vapour which is known to be lighter than surrounding atmosphere.

However this design has two drawbacks, the first of which is its high energy consumption due to the high temperature of the water used that causes a higher heat exchange with the cabin walls and a drainage of very hot water in the waste system. The second drawback comes from the fact that the high temperature of the water may accidentally scald the user's legs, even though the system is designed to avoid this. The second design used to generate steam inside the shower box consists in bringing steam directly inside it through a special boiler, but again this has an important drawback. Firstly, the generation of steam requires high electric power (up to 5 KW) to ensure that the sauna cabin is ready for use in a reasonably short

time. Secondly, although the steam expansion at nozzle outlet implies a considerable reduction of temperature, there remains the risk of accidental scalding. The best known solution offered to reduce the above risks involves electronic adjustment for a more precise temperature control of flows, but the advantage so offered is offset by the disadvantage of higher costs and, above all, by electric circulation in an environment which, being in contact with water, requires severe and expensive safety measures that in any case may be compromised even with normal use. The scope of this invention is to define a single or double sauna cabin able to adopt very safe criteria for the heating and the inner generation of steam, that protects against both electrocution and accidental scalds. Another scope is to define a cabin, as above, able to grant a high cost saving. A further scope is to define a cabin that can reach the optimal desired temperature and humidity parameters in short time. Another scope is to define a cabin, as above, requiring no steam generators going beyond the intrinsic capacity of the domestic water system.

DISCLOSURE OF INVENTION These and other scopes will be seen to have been achieved by reading the detailed description which follows. This illustrates a single or double sauna cabin

having the peculiarity of adopting a thermostat which regulates the mixing of cold water with hot water from the traditional supply system of sanitary fittings at a pre-set safety temperature of about 55° C. This thermostat serves a two-way cock with sequential selection and manual control in order to spray thermostated hot water, first, to two nozzle sets during a preparatory heating phase of the empty cabin and then to one set aimed at maintaining the temperature degree and steam content at the level previously set. The spraying action of thermostated hot water jets is directed towards the upper surfaces of the cabin to allow water to run over the inner walls of the cabin when running down in a suitable quantity and adequately distributed to transfer its heat until the ambient temperature is reached before water is discharged into the traditional waste pipes.

BRIEF DESCRIPTION OF DRAWINGS As an example, the invention is illustrated by, but is not limited to, the enclose drawings, in which : -Fig. 1 shows, in side-view, the interior of a sauna cabin and the position of water jets heating the cabin ; -Fig. 2 shows, in side view, the interior of the sauna cabin, as above, indicating only the position of water jets designed to maintain the desired high temperature and

degree of humidity, reproducing the profile of a user sitting inside it ; -Fig. 3 shows the plan view of the interior of the sauna cabin, as above, indicating the direction of the water jets designed to maintain the desired high temperature and degree of humidity when the user is sitting inside the cabin ; -Fig. 4 shows a plumping pipe run required for the above.

BEST MODE FOR CARRING OUT THE INVENTION With reference to the above mentioned Figures 1,2,3 the cabin interior, which is usually constructed from thermoformed six-millimetre thick acrylic laminated plastic, has several functional protrusions forming a seat 1, a number of brackets 2, aesthetic trims 3, baffles 4, stiffening ribs or bosses 5 containing the technological equipment on the back. The shapes shown are merely illustrative; they serve to express the presence of the elements in question that can therefore take on the most various functions according to the possible aesthetic- design variations of the cabin. Their common scope however consists in that they avoid the formation of depressions where water may stagnate and allow frontal 6 and back 7 water jets to continuously cover as large a surface as possible with minimum slow down. This allows the hot water running slowly down the surfaces to easily

transfer its heat so that it can pour from the usual drainage pipes at a temperature that is as near as possible to the ambient temperature. Figure 1 shows that water hits the cabin walls in the upper area. This cabin heating phase uses water at a temperature of about 55° C at a pressure of 1.5 bar with a flow rate of about 7 litres per minute. Because of this, and due to the poor thermal conductivity of the laminated plastic surfaces and of the glass making up the cabin, the temperature reaches the desired value of about 45° C in less than two minutes. At this point the user manually opens a cock that closes the spraying nozzles in the back inner parts of the cabin, leaving the three jets toward the frontal zone 8 free to spray. Fig. 3 shows the position of said frontal zone 8 and also the sitting position of a user 9. This figure clearly shows that water H is turned toward zones that are far from the user, even though it is not at a scalding temperature, thus offering the user the maximum safety and allowing him to physically and mentally relax. With reference to the piping diagram in figure 4, the realisation mode of the invention can be seen. Hot water comes in through a pipe 10 at a temperature of about 60°. This hot water can be produced in many usual ways: centralised installation, electric boiler or flame boiler. Said hot water reaches a thermostat 11 adjustable in a range of

temperatures between 37 and 55° C. A pipe 12 is connected to this thermostat and is supplied by the domestic cold water system at a temperature of about 15° C. This thermostat 11 is equipped with an outlet pipe 13 with water at the set temperature, for instance 50° C. This pipe joins a two-way 15 and 16 manual deviator 14. Way 15 flows into a set of about four nozzles 17 creating the water jets 7; way 16 flows into another set of about three nozzles 18 generating the front water jets 6. The two pipes 15 and 16 are connected each other through a one- way no-return valve 19 that allows the jets from nozzles 17 to add to those from nozzle 18, but does not allow jets from nozzles 18 to add to those from nozzles 17, since the two pipes 15 and 16 are selectively used for thermostated water passage through the manual deviator 14 and can therefore be operated separately.