US 3588470 A
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United States Patent 1,462,224 7/1923 Bansert Inventor Max R. Husband Kalamazoo, Mich.
Appl. No. 790,402
Filed Jan. 10, 1969 Patented June 28, 1971 Assignee Patrick 11. McCauley Kalamazoo, Mich. fractional part interest ELECTRIC SAUNA BATH HEATER 1 Claim, 2 Drawing Figs.
4/160, 219/275. 219/430, 219/535 Int. Cl F24h 7/00,
Field of Search References Cited UNITED STATES PATENTS 3/1949 Stansbury 219/422 6/1950 Biebee 219/535X 9/1953 Sandberg 219/378 5/1956 Deane 219/429UX 11/1963 Vanne et a1... 219/378X 3/1967 Dow et a1 219/378 3/1968 Williams 219/367 FOREIGN PATENTS 6/1931 Switzerland 219/378 6/1961 Sweden 219/378 9/ 1949 France 219/378 Primary ExaminerVolodymyr Y. Mayewsky Attorney-Woodhams, Blanchard and Flynn ABSTRACT: An improved electrical resistance-type heating source for use in a sauna bath is comprised of an upright, open-top, closed-bottom, hollow container having imperforate walls, which container has electrical resistance heating bands affixed to the exterior surface thereof and which container is substantially filled with solid, nonporous rocks.
ELECTRIC SAUNA BATH HEATER This invention relates to a sauna bath and, more particularly, relates to an improved electrical resistance heating-type heat source for use in a sauna bath.
A wide variety of heat sources have been suggested for use in sauna baths. In recent years, the use of electric heat sources for sauna baths has become widespread, particularly for installations in hotels, motels, health centers and the like, because of their relatively low cost and ease of installation, operation and maintenance. However, such electric heat sources for saunas have not been completely satisfactory for a number of reasons. One problem is that an unpleasant odor becomes present in the sauna room in the course of time. Also, scum or residues collect on various surfaces in the sauna room, particularly on or closelyadjacent the surfaces of the heat source itself. Therefore, in order to minimize these problems, and to comply with sanitation regulations of state and/or municipal authorities, it is necessary toprovide ventilation systems, which can be quite elaborate, and also periodically to clean the sauna room including the heat source thereof. The cleaning procedurecan be quite time consuming and expensive, particularly when same involves cleaning the surfaces of the heat source itself.
A further deficiency of known electric heat sources for saunas is that they do not maintain as good comfort and refreshment conditions in the sauna room as is desired. That is, they do not achieve the same comfort and refreshment conditions inv the sauna room as are achieved by the original wood-fired types of saunas.
Accordingly, it is an object of this invention to provide an improved electric heat source for a sauna bath which minimizes the unpleasant odors that become present in the sauna room. v
It is a further object of this invention to provide an improved electric. heat source, as aforesaid, which also minimizes the amount of scum or residues deposited in the sauna room and causes same to be deposited in the sauna room and causes same to be deposited in areas in which they can easily and conveniently reached for cleaning, whereby the sauna room requires less cleaning and the cleaning can be carried out more easily and quickly.
It is a further object of this invention to provide an electric heat source for a'sauna bath, as aforesaid, which provides a high level of comfort and refreshment conditions in the sauna room.
Other objects and advantages of the invention will become apparent to persons acquainted with apparatus of this type upon reading the following description and inspecting the accompanying drawings, in which:
FIG. I is a sectional view of a sauna room.
FIG. 2 is a sectional view of the electric heat source according to the present invention, the sectional view being taken along the line ll-II of FIG. 1.
According to the invention, there is provided an electric heat source for use in a sauna room which heat source is comprised of an upright, open-top, closed-bottom, hollow container having imperforate walls in order to prevent the upward flow of air through the container. The bottom has substantially the shape of one-half of an oblate spheroid. The container is substantially filled with solid, nonporous rocks which serve as a radiation heat source of the sauna room. A plurality of vertically spaced, generally horizontally arranged electrical resistance heating bands encircle and are attached to the exterior surface of the container and are disposed in continuous touching relationship therewith over substantially the entire circumference of the container in order to radiate heat in a generally radial direction into the interior of the container and thereby heat the rocks contained therein.
DETAILED DESCRIPTION Referring to FIG. 1, there is illustrated a sauna room having four sidewalls, three of which are shown at 11, 12 and 13, a
top wall or ceiling 14 and a bottom wall or floor 16. A door (not shown) is provided in one of the sidewalls to permit the sauna bathers to enter and leave the room. Although normally it is not necessary to provide a ventilation system for a sauna room using the heat source according to the present invention, it may be found desirable to provide a port or aperture in the door or other part of the room inorder to permit air to flow into and out of the sauna room. A series of benches 17, 18 and 19 are provided along one side of the room in a conventional fashion. It will be understood that other bench and seat arrangements can be used, in place of the particular arrangement illustrated in the drawings. The benches l7, l8 and 19 and the interior surface of the walls of the rooms are usually made of or are lined with wood in a conventional fashion.
A heat source 21 is located inside the room 10, usually adjacent one of the corners thereof. The heat source 21 may be located within a protective fence 20 in order to prevent injury to the users and to prevent damage to the heat source.
The heat source 21 is comprises of an open-top, closed-bottom, cylindrical container 22 having a sidewall 23 and a concave, generally cup-shaped bottom wall 24. The sidewall 23 is of constant diameter throughout its length so that it defines an interior zone therewithin, which zone is circular in cross section. The bottom wall 24 is united to and merges smoothly at its upper end with the lower end of the sidewall 23. The bottom wall 24 is smoothly curved an inward and downward direction in order to close the bottom end of the circular interior zone. The bottom wall 24 desirably has substantially the space of one-half of an oblate spheroid. The sidewall 23 and the bottom wall 24 are of uniform, identical wall thickness throughout their lengths. They are made of heat-conductive metal,. preferably of galvanized steel sheet for purposes of economy and reasonably effective corrosion resistance. It is especially to be noted that the sidewall 23 and the bottom wall 24 are imperforate and closed so that air does not flow therethrough. However, a drain spigot (not shown) is provided at the lowermost point on the bottom wall 24 to permit draining of any water that may accumulate in the container.
A plurality of horizontally arranged, flat, electric heating bands or strips encircle, are secured to and are disposed in contiguous relationship with the external surface of the sidewall 23 at vertically spaced-apart positions thereon. In the illustrated embodiment, two such heating bands or strips 26 and 27 are used. The upper heating band 26 is located close to, but spaced downwardly a few inches from, the upper end of the container. The lower heating band 27 is located close to the bottom edge of the sidewall 23. The heating bands 26 and 27 are constructed and arranged so that they are capable of supplying different amounts of heat to the contents of the container. For example, it is preferred that the upper heating band 26 have a heat supply rating of about 3500-4000 watts and that the lower heating band 27 have a heat supply rating of about 2500-3000 watts.
The bands 26 and 27 are in the form of elongated members of relatively thin cross section. They may contain electrical resistance heating elements, such as coils or wires, which are positioned in closely adjacent relationship with the external surface of the sidewall 23. The electrical resistance heating elements are surrounded on their outer sides by a protective metal shell. Heat insulation may be provided between the electrical resistance heating elements and the shell in order to minimize heat transference to the shell. However, the active electrical resistance heating elements themselves are positioned in closely spaced relation to the sidewall of the container in order to transmit a maximum amount of heat thereto. Electrical power is supplied to the bands 26 and 27 at the regular power line potential through a conductor 30 and a junction box 30A. The supply of electric power to the bands 26 and 27 may be controlled by a thermostat (not shown) in the sauna room in order to maintain proper temperature conditions therein.
The container 22 is supported on and is spaced vertically from the bottom wall 16 of the sauna room by legs 29.
The container 22 is substantially filled with a quantity of stones or rocks 31. .The rocks may be of random sizes and shapes although it is preferred that each rock be at least several inches long in its longest dimension. The rocks should be substantially solid and nonporous. It is preferred to use common field stones for this purpose.
A manually controllable water supply nozzle 32 is suspended above the upper end of the container 22 so that water can be sprayed onto the outer layers of rocks 31, when desired, in order to increase the humidity in the sauna room. It is preferred that the nozzle 32 supply water in the form of a relatively fine spray. Nozzles capable of doing so are readily commercially available.
In using the apparatus described above, the heating bands 26 and 27 are energized in order to maintain proper desired temperature conditions in the sauna room. If it is desired to have low humidity conditions in the sauna room, the water supply nozzle 32 will not be actuated so that no water vapor is added to the room atmosphere. Ordinarily, when low humidity conditions are provided, the room temperature is maintained at a relatively high level and the thermostat can be set as desired in order to provide the desired sauna room temperature.
If it is desired to increase the humidity level in the sauna room, the same can be done by manually actuating the water supply nozzle 32 whereby to spray water on the rocks. This water will be substantially vaporized on contact with the heated rocks and it will then travel through the sauna room as a result of the normal air circulation that occurs therein. When a humid atmosphere is maintained in the sauna room, ordinarily the room temperature will be maintained at a lower level.
The electrical resistance heating bands 26 and 27 will supply heat uniformly around the entire circumference of the container and such heat radiates inwardly in a generally radial direction in order to heat the rocks by conduction and radiation. Because a greater amount of heat is supplied by the upper band 26, the rocks in the upper portion of the container 22 are heated to a somewhat higher temperature than the rocks in the portion of the container. A result of this is that a steamy or misty atmosphere is not present in the zone immediately above the upper end of the container 22, even when the sauna room has a' high humidity level, because the higher temperature of the rocks and the air immediately thereabove prevents any condensation of the vaporized water. When water is sprayed on the rocks so that it is immediately vaporized, a steamy or misty atmosphere does not extend much above a level of about one foot above the upper level of the rocks because of the relatively high air temperature in this zone. When the spraying of the water onto the rocks is stopped, the steamy or misty atmosphere disappears very rapidly.
It will be observed that because the container 22 is closed, except at its upper end, there is little or no air circulation through the interior of the container. There may be some air circulation across the top of the container so that there may be some relatively minor amount of air movement through the upper layer of rocks. However, the predominant air circulation in the sauna room extends through a path beginning at the upper end of the container, thence around the entirety of the room and return to the zone around the lower end of the container and thence along the outside of the container to the point of beginning. Inasmuch as there is little or no air circulation through the interior of the container 22, the heating effect caused by the electric resistance heating bands 26 and 27 is predominantly the result of heat radiation from the rocks and there is relatively little heat transfer caused by convection currents caused by air rising through the spaces between the rocks. This is in .contrast to other known electrical heat sources for saunas, with which lam familiar, in which the air is purposely caused to flow through the container upwardly between and around the rocks. The prior electrical heat sources for saunas provide openings in the sidewall and/or the bottom wall of the heat source, together with various types of louvers or baffle arrangements in order to control and channel such airflow.
Because of the fact that, according to the present invention, the heating effect is predominantly caused by heat radiation from the rocks, rather than by convection currents, there results a significantly different operation which has the following effects:
l. The rocks are maintained ata higher temperature. This minimizes any buildup of scum or residues thereon which improves the sanitary conditions inside the container. Further, this is believed to contribute to the other advantageous effects referred to below.
2. The air circulation in the sauna room is different than the air circulation which results when other known electrically heated sauna installations are used. According to the present invention, air passes around the outside and perhaps, to some extent, over the container, rather than through the container. It has been found that the scum or residues are condensates that fonn in a sauna room as a result of evaporation of perspiration and the like. When the electric heating unit accordingto the present invention is used, these are deposited on the floor in zones around, but spaced from, the heat source and they do not form on the surfaces of the heating source itself. These condensates thus accumulate'at locations where they can be quickly and easily cleaned. in contrast to this, the use of electrical heat sources for saunas in which the air is caused to flow through and around the rocks results in the accumulation of condensates on various surfaces, including the rock surfaces, where they are very difficult to reach. Consequently, it is required that the sauna room be closed down for substantial periods of time in order to effect the required cleaning thereof.
3. A further important result of the use of the electrical heat source according to the present invention for a sauna room is that it has the effect of creating ozone in the air circulating inside the sauna room, particularly when water is sprayed onto the rocks. The exact mechanism by which this ozone formation occurs is not understood, but it appears to be due to certain instantaneous reactions or effects which take place because of the higher rock temperatures and the heat radiating efi'ect thereof. It has been observed that there is a detectable ozone odor in the circulating air inside of a sauna room equipped an electric heat source according to the present invention. A further reason to believe that ozone odor in the circulating air inside of a sauna room equipped an electric heat source according to the present invention. A further reason to believe that ozone becomes present in the sauna room is that the unpleasant odor in the sauna room is reduced and also there is a reduced accumulation or production of scum or other residues. Since ozone is known to be an effective disinfectant and deodorizer, it is believed that the desirable results referred to above are achieved because ozone is produced by use of the heat source according to the present invention.
Thus, the present invention provides an improved electric heat source for a sauna room which is relatively simple in construction and which is inexpensive to manufacture and maintain in operating condition. It has significant operating advantages as compared with other prior art electrical heat sources, particularly because of the fact that the heat is sup plied to the sauna room primarily by radiation, rather than by convection.
l. A heat source for a sauna room, comprising:
an upright, open-top, closed-bottom, hollow container of heat conductive metallic material and having imperforate walls to prevent the upward flow of air through the container, the container being substantially filled with solid, nonporous rocks for radiating heat into the sauna room through the top of the container,
said container comprising a cylindrical imperforate sidewall which is of constant diameter throughout its length to define an interior zone which is of circular cross section,
said container also having a concave imperforate bottom wall which extends downwardly from the lower end of the sidewall and closes the bottom end of the container, the sidewall and the bottom wall being of integral construction and being made of corrosion-resistant sheet metal,
a pair of vertically spaced external heating devices attached nectable to a source of electrical energy for radiating heat in a generally radial direction into the interior of the container and thereby heating the rocks contained therein, the heating band means being electrically insulated from the container the uppermost heating device having a higher wattage rating than the lower heating device in order that the rocks at the upper end of the container receive a greater amount of heat and are heated to a higher temperature than. the rocks in the bottom of the container to thereby maintain a relatively high temperature zone above the upper end of the container whereby to minimize the presence of mist thereat, said container having supports extending downwardly therefrom for supporting the container at a position spaced vertically from the bottom wall of the sauna room.