US3348021A

US3348021A - Electric heater assembly for a sauna room

Info

Publication number: US3348021A
Application number: US432708A
Authority: US
Inventors: Skogland Thorbjorn; David M Checkley
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1965-02-15
Filing date: 1965-02-15
Publication date: 1967-10-17
Anticipated expiration: 1984-10-17

Description

@Ct 17, 1967 T. SKOGLAND ETAL. 3 9

ELECTRIC HEATER ASSEMBLY FOR A SAUNA ROOM Filed Feb. 113, 1965 5 Sheets-Sheet -l 2 9/ @cit. 17, 1967 T SKQGLAND ET 3,348,132

ELECTRIC HEATER ASSEMBLY FOR A SAUNA ROOM Filed Feb. 15, 1965 5 SheQ'LS-ShEGb 2 fiitownezy ELECTRIC HEATER ASSEMBLY FOR A SAUNA ROOM Filed Feb. 15, 1965 5 SheetsSheet l5 United States Patent 3,348,021 ELECTRIC HEATER ASSEMBLY FOR A SAUNA ROOM Thorbjorn Skogland, Shelbyville, Ind., and David M. Checkley, Seattle, Wasln, assignors to General Electric Company, a corporation of New York Filed Feb. 15, 1965, Ser. No. 432,708 5 Claims. (Cl. 219-370) ABSTRACT OF THE DISCLOSURE A heater assembly for a sauna room and the like including a heated case mounted in a wall by means of a mounting section in order to insulate the case from the wall. The case includes high and low temperature heating chambers, defined by the front wall and front and rear pans, with an insulation layer between the rear pan and rear wall for providing additional insulation with the mounting wall. An electric motor for driving a blower has a portion extending rearwardly beyond the insulation layer into the mounting section to permit the motor to dissipate heat in the mounting section. A sauna simulatingstone tray is mounted on the front wall of the case and heated air will pass over stones carried in the stone tray.

This invention relates to electric heater assemblies and particularly to heater assemblies which are adaptable for use in a sauna room and the like.

In room heating applications, such as for example in a sauna room, it is necessary to provide a heater assembly that will supply a source of relatively dry air heated to relatively high temperatures. The air in a typical sauna room is heated to a temperature of about 175 degrees Fahrenheit and the relative humidity is usually below percent. By way of comparison, in a steam bath room, the temperature of the air generally does not exceed 130 degrees Fahrenheit, and the relative humidity isapproximately 100 percent. I

Traditionally, sauna rooms have utilized heated stoves to bring the air in the room to the desired temperature. These stoves were heated by means of gas, coal or wood fired heaters. Recently, it has been found to be more convenient to heat the air directly by means of electric resistance heaters of suitable capacity and design, to relatively high temperatures. It is also desirable that the heater automatically maintain the room at the desired temperature. In order to achieve more uniform temperature distribution within the room, it is desirable to introduce forced air convection means within the heater. In many applications it is particularly desirable that the heater be capable of being mounted in the wall of the room. Where the heater is wall mounted, it should, of course, comply with Underwriters Laboratories requirement that no point of the heater contacting the wall exceed 190 degrees Fahrenheit.

Accordingly, it is an object of the present invention to provide an improved heater assembly havingthe heat capacity requirements for room heating applications such as sauna rooms and the like. 7

It is another object of the present invention to provide an improved heater assembly capable of heating air to i a temperature as high as 175 degrees Fahrenheit.

In accordance with one form of the invention the improved heater assembly includes a case having a rear wall and a front wall formed with an air outlet through which the heated air discharges when the heater assembly is in operation. To channel the flow of heated air, the heater assembly is provided with a front and a back pan. The

' back pan is supported in spaced relation with. respect to.

ice

the rear wall, and a layer of suitable thermal insulating material, such as fiberglass, is interposed between the back pan and the rear wall of the case.

The back pan is formed with a skewed portion that extends toward the front wall. The front pan is supported by the rear wall and is disposed in spaced apart relation with the back pan to form a low temperature heating chamber. Like the back 'pan,'the front pan also is formed with a skewed portion so that the flow of air is deflected toward the air outlet. A high temperature heating chamber is formed between the front wall of thecase and the front pan.

To cause the air to flow through the low temperature and high temperature chambers a blower driven by an electric motor is located near the bottom of the low and high temperature chambers. According to one aspect of the invention the electric motor is located so that at least a portion of the motor extends outwardly of the layer of thermal insulating material.

Air circulating through the high temperature heating chamber'is heated by a plurality of heating elements disposed in the path of the air flow. In the low temperature chamber the air circulates at relatively higher velocities than the air in the high temperature heating chamber and is heated by the heat energy transmitted through the front pan. In effect, the air flowing through the low temperature chamber serves as a thermally insulating blanket to prevent overheating of the rear wall of the case.

In a more specific aspect of the invention, in order to prevent the temperature adjacent to the skewed portion of the back wall from exceeding predetermined limits,

thermal cutouts are employed to selectively de-energize the resistance heating elements when the temperature becomes excessive. A temperature sensing element of a control thermostat is provided at the inlet of the blower to sense the temperature of the air drawn into the blower from the room. The control thermostat causes the heating elements to be de-energized when the air inlet temperature reaches a selected level at which it is desired to maintain the-room to be heated; The heating elements are again energized when the temperature falls below the selected level.

Where the heater assembly is used to heat a sauna room, a stone tray may be provided at the front wall of the case adjacent to at least a portion of theair outlet so that the heated air will discharge into the stone tray to heat the stones in the tray. 7 g 1 An important advantage of the improved heater assembly arrangement is that it is possible to heat air at relatively high temperatures, such as for example Fahrenheit, without need for a motor that must withstand these relatively high temperatures. Also, the improved heater assembly can be readily mounted'in a wall since the points at which the case of the heater assembly is brought in contact with the wall can be maintained within predetermined safe limits.

The subject matter we regard as our invention is set forth in ,the appended claims. The invention itself, however, together with further objects and advantages thereof may be understood by referring to the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a front elevational view of the heater assembly incorporating one form of the invention and having the front panels cut away to show the internal arrangement; 7

FIGURE 2 is a sectional view of the heater assembly illustrated in FIGURE 1, the section being taken generally along line 2-2 of FIGURE 1;

FIGURE 3 is a perspective view of the heater assembly mounted in the wall of a sauna room;

FIGURE 4 is a side view of the heater installed in a wall, the wall and guard rail being shown in section; and

FIGURE 5 is a schematic circuitdiagram of the heater circuit.

Having more specific reference to FIGURES 1 through 4 of the drawings, we have illustrated a heater assembly which is identified generally by the reference numeral 10. The heater assembly includes a case 11, a front section 12 and a mounting section 13. The front section 12 includes a front panel 14 and a stone tray 15 in which stones may be placed if desired. It will be appreciated that in the traditional sauna heater, heated stones were used to bring the room to the desired temperature.

The mounting section 13 includes a back support section 16, a junction box 19, an access panel 17 and a lower louvered portion 18. The lower louvered portion 18 allows air to circulate through the mounting section 13. It will be noted that a portion of the blower motor 20 extends into the mounting section 13 so that heat generated by the motor windings can be effectively dissipated to the ambient air in the mounting section 13.

An important advantage of this arrangement is that it makes it possible to use a special motor designed for operation in a high temperature ambient. It will be appreciated that heaters which utilize forced conviction and are supported on the floor of the sauna room must be specially constructed in order to operate in the high ambient temperature of the sauna room, which may exceed 175 Fahrenheit.

In the interest of simplification the electrical leads and their connections have been omitted from the sectional view of FIGURE 2. It will be understood that the leads -for connection to a power supply are brought out from the junction box 19. The specific circuit connections of the various electrical components are shown in FIGURE 5 and will hereinafter be more fully described.

As is best seen in FIGURE 2, case 11 of the assembly 10 includes a rear wall 21, a front wall 22 formed with an air outlet 23, an opening '24, and a wraparound section 25 which provides the side and top walls of the case 11. The air outlet 23 is comprised of upper and a

lower grille

27 and 28, respectively. The lower grille 28 is adjacent to the stone tray 15 and allows air to circulate into the tray 15 to heat up any stones placed therein.

It will be seen that a back pan 29 is supported in spaced relation with respect 'to the rear Wall 21 by means of a plurality of spacers 30 and screws 31. As is shown in the cross sectional view of FIGURE 2, an insulating barrier or wall of insulating material 32 is interposed between the rear wall 21 and the back pan 29. A front form a high temperature heating chamber 40'. The low and

high temperature chambers

34 and 40 communicate near the top of the case 11 with the air outlet opening 23. A blower 41 located at the bottom of the

heating chambers

34, 40 causes air to be circulated through the

chambers

34, 40 andto discharge through the outlet opening 23 into theroom in which the heater 10 is operated.

In the illustrated embodiment of the invention, the air flowing through the high temperature chamber 40. is heated by means of electrical

tubular heaters

42, 43 and 44. As shown, the

tubular heaters

42, 43 and 44 are supported in the high temperature chamber 40, and positionedover a deflector 45. The terminals 46, .47, 48, 49, and 51 of the

tubular heaters

42, 43 and 44 are brought out through the back wall 21 into the mounting section 13. The tubular heaters or

elements

42, 43 and 44 are preferably of the enclosed metal sheathed type in which a resistance heating conductor is enclosed within a metal sheath and separated therefrom by an electrically insulating and heat conducting material such as compacted magnesium oxide powder.

Preferably, the heater assembly 10 is supported by mounting brackets 60, 61 (see FIGURE 1) and adapted to engage the

brackets

62, 63 attached to the wall opening 64. The access panel 17, as is best seen in FIGURE 2, is removable to permit access to the wiring box 19. Because of the hot metal surfaces of the heater assembly during operation, a heater screen 65 fabricated of wood, as shown in FIGURES 3 and 4, should be provided around the heater assembly 10 at a location of at least three inches from the heater case 11 as to prevent one from accidentally touching the hot metal'during operation and receiving a burn In order to prevent the front panel 14 of the heater assembly 10 from becoming excessively hot, suitable insulation 53 such as fiber glass, is provided between the stone tray 15 and the front panel 14. An opening 54 is provided at the bottom of the front panel 14. Thus, air enters into the. heater assembly 10 through the opening 54, and is drawn into the inlet 55 of the blower 41.

The blower 41 used in the illustrated exemplification of the invention is of the centrifugal type and is driven by the electric motor 20. The blower 41 discharges air through the deflector 45 into the low and high

temperature heating chambers

34 and 40. As is shown in FIG URE l, a temperature sensing element 56 is located near the blower inlet 55. In the improved heater assembly 10 for use in a sauna room, a thermostat 57 with a control knob 58 is provided to control the temperature of the sauna room by sensing the temperature of the air drawn from the room into the blower inlet 55. Since the heater assembly 10 recirculates the air in the room being heated, the air at the blower inlet 55 of the heater assembly 10 is essentially at the temperature level of the room. When the temperature of the air at the blower inlet 55 reaches a predetermined level, the thermostat 57 actuates a switch 'which turns off the power supplied to the tubular heaters To provide protection against possible overheating, three automatic resetting temperature responsive or thermostatic switches or

cutouts

66, 67 and 68 cut off the

tubular heaters

42, 43 and 44, respectively, from the "power source in response to the temperature of the heated air flowing in the low temperature chamber 34. When the heater air in the low temperature chamber 34 exceeds a predetermined limit, the thermostatic switches will open to, cut out the heaters and will automatically cause the

heaters

42, 43, 44 to be cut back in when temperature becomes normal.

Having more specific reference now to the schematic circuit diagram shown in FIGURE 5, we will now more fully describe the electrical circuit of the improved heater assembly 10; In the schematic circuit diagram, like reference numerals are used to identify the parts that correspond to the heater assembly illustrated in FIGURES 1 and 2. The heater assembly 10 is schematically represented in FIGURE 5 by the dot-dash rectangle and includes tubular heaters42, 43 and 44. A pair of input terminals 70 and 71 are provided for connection to a suitable alternating power source, such as a 240-volt alternating supply (not shown). It will be noted that tubular heater 42 is connected in circuit across the input terminals 70' and 71 by means of

leads

72, 73, the thermostatic switch 67, leads 75, 76 and the temperature actuated switch 77 of the control thermostat 57. The second tubular heater 43 is connected across the input terminals 70 and 71 by

leads

78, 79, and lead 80, the

thermostatic switch 68, lead 76 and temperature actuated switch 77. Similarly, the third tubular heater 44 is connected across terminals 70 and 71 through a circuit which may be traced, starting with terminal 70, through lead 81, thermostatic cutout 66, lead 82, terminal 51, tubular heater 44, terminal 50, a switch 74, lead 83, and thermostat switch 84 to input terminal 71. Switch 84 of the thermostat 57 is open in its off position, and closes as the thermostat 57 is increased in setting. It energizes heater 44 which operates continuously and allows

only heaters

42 and 43 to cycle with room ambient. .After initial heat up, it can be permanently removed from the circuit by operating switch 74. Switch '74 also permits the tubular heater 44 to be disconnected when the heater assembly is adapted for heating smaller rooms.

In order to insure that the motor is not turned off when anyone of the

thermostatic cutouts

66, 67, 68 is actuated, the supply lead 86 of the motor 20 is connected in electrical circuit with the input terminal 70 and the other supply lead 87 is connected to the other input terminal 71 so that the motor 20' is not de-energized whenever one or more of the

switches

66, 67 and 68 are opened. Thus, motor 20 is continuously energized so long as power is supplied to the input terminals 70 and 71.

The heater used in the illustrated embodiment of the invention was adapted. for heating a relatively large sauna ,room having a volume of approximately as high as 840 cubic feet. With the switch open the heater unit was capable of heating smaller sauna rooms up to approximately 560 cubic feet in size. It will be understood that a sauna room is normally heated to a temperature ranging from 175 degrees Fahrenheit to 190 degrees Fahrenheit. v Whenthe input terminals 70 and 71 are energized and the control thermostat 57 is set to the selected temperature to which it is desired to heat the sauna room, the

heater assembly begins to operate. Let us assume, for example, that the selected temperature is 175 degrees Fahrenheit. During the preliminary warm up period the thermostat switches 77 and 84 of the control thermostat 57 are closed, and the three

thermal cutouts

66, 67 and 68 "are also closed. The blower motor 20 is energized, and

air circulates through the low and hightemperature heating chambers 34, 4% (see FIGURE 2); The air circulat- ,ing through the low temperature chamber 34 provides an approximately 300 degrees Fahrenheit and to reclose at a temperature of about 220 degrees Fahrenheit. The

thermal cutouts

66, 67 and 68 come into play only when the temperature of the air circulating through the low temperature chamber 34 is sufficient to actuate the thermal cutouts. Regardless of the number of

tubular heaters

42, 43 and 44 that are de-energized by the

thermal cutouts

66, 67 and 68, the blower motor 20 continues to be energized to circulate air through the chambers 34 and to provide cooling air therethrough. In this manner possible overheating of the heater assembly 40 is prevented.

When the air flowing through the low temperature heating chamber 34 drops sufiiciently to reclose the

thermal cutouts

66, 67 and 68, the

tubular heaters

42, 43 and 44 are again energized. When the temperature of the air at the blower inlet reaches the temperature level at which the control thermostat 57 is set, the switch 77 opens to deenergize the

tubular heaters

42 and 43. When the temperature of the air at the inlet of the blower 41 sensed by the control thermostat falls below 175 degrees Fahrenheit, the switch is again closed to energize the

tubular heaters

42 and 43.

From the foregoing description of the structural features and the mode of operation of the improved heater assembly, it will be apparent that with the improved arrangement it is possible to provide a heater assembly 6 that is capable of supplying a relatively high beat output and that can also be mounted within a wall opening. Although the heater assembly described by way of exemplification of the invention was employed as a sauna heater, it will be apparent that the improved heater assembly may be used in other room heating applications.

While the present invention has been described by reference to a particular embodiment thereof, it will be understood that many modifications may be made by those skilled in the art without actually departing from the invention. It is therefore intended by the appended claims to cover all such modifications that fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A heater assembly comprising: a case including a rear wall, and a front wall with an air outlet and an air inlet, a back pan supported in spaced relation to said rear wall, said back pan having a skewed portion extending at the top toward said front wall, a front pan supported on said rear wall and in spaced apart relation with said back pan to define a low temperature heating chamber therebetween, said front pan having a skewed portion at the top extending toward the front wall and defining a high temperature heating chamber between said front wall and said front pan, a plurality of electrical resistance heating elements disposed in said high temperature heating chamber, means for energizing said electric resistance heating elements from an alternating source, means for circulating air through said high and low temperature chambers, a stone tray supported at the front wall of said case and adjacent to at least a portion of said outlet opening to allow heated air discharging from at least a portion of the air outlet to pass into the stone tray, and means disposed in said low temperature heating chamber and responsive to the temperature in said low temperature heating chamber for preventing the temperature of the air in said low temperature heating chamber from exceeding predetermined limits by deenergizing said heating elements when said predetermined limits are reached.

2. A heater assembly comprising: a case including a rear wall, an air inlet and a front wall formed with an air outlet, a back pan supported in spaced relation with respect to said rear wall, said back pan having a skewed portion extending toward the front wall, insulating means disposed between said back pan and said rear wall and along the skewed portion of said back pan, a front pan spaced from said back pan and having a skewed portion extending towards the front of said enclosure to define a low temperature heating chamber between the back pan and front pan and a high temperature chamber between the front wall and front pan, said chambers communicating with the outlet formed in the front side of said case, blower means including air inlet means in communication with the air inlet in said case, said blower means being disposed at the bottom of said low temperature and high temperature chambers and communicating therewith to cause air to fiow therethrough, said blower means including an electric motor having a portion thereof extending rearwardly of said insulating means, electrical heating means disposed within said high temperature chamber for heating air flowing therethrough and a stone tray supported at the front wall of said case adjacent to at least a portion of said outlet to thereby cause air to be discharged into said stone tray.

3. A heater assembly comprising: a case including a rear wall, a mounting section attached to said rear wall for mounting the heater assembly in a supporting structure, said case including a front wall formed with an air inlet and an air outlet, a back pan supported in spaced relation with respect to said rear wall, said back pan having a portion extending toward the front wall, insulating means disposed between said back pan and said rear wall, a front pan supported by said back wall and in spaced apart relationship with said back pan to define a 7 low temperature heating chamber therebetween,. said front pan having a portion extending towards said front wall, said front pan defining a high temperature heating chamber between the front'wall and front pan, said low temperature and high temperature chambers communicating with said air outlet, electrical heating means disposed within said high temperature heating chamber for heating the air circulating therethrough, blower means for circulating air through said high and low temperature chambers, said blower means including an air inlet in communication with the air inlet in said front wall, said blower means including an electric motor having a portion thereof extending rearwardly of said insulating means into said mounting section thereby to permit the heat generated by said motor to dissipate within the mounting section, and means mounted in said low temperature heating chamber and being responsive to the temperature in said low temperature heating chamber for preventing the temperature of the air in said low temperature chamber from exceeding predetermined limits by deenergizing said electric heating means when said predetermined limits are reached.

4. A heater assembly comprising: a case including a rear wall, and a front wall formed with an air inlet and an air outlet, a back pan supported in spaced relation with respect to said rear wall, insulating means disposed between said back pan and said rear wall, a front pan spaced from said back pan and defining therebetween a low temperature heating chamber communicating with said air outlet, said front pan and said front wall defining a high temperature heating chamber, said high temperature heating chamber also communicating with said air outlet, electrical blower means for circulating air through said high and low temperature heating chambers, said electric blower means including air inlet means in communication with the inlet in said front wall, said blower means including an electric motor having a portion thereof extending rearwardly of said insulating means out of said case thereby to permit the heat generated by said motor to dissipate out of said case and said portion to remain at a relatively cooler temperature than the temperature within the case, a plurality of electrical resistance heating elements disposed in said high temperature heating chamber for heating air flowing therethrough, first temperature responsive means disposed in said low temperature heating chamber for. preventing the air flowing through said low temperature heating chamber from exceeding a predetermined limit by deenergizing said heating elements when said predetermined limits are'reached, and second temperature responsive means disposed adjacent to the air inlet means of said electric blower means for deenergizing said heating elements when the temperature of the air at the air inlet means of said blower means reaches a predetermined level.

5. A heater assembly comprising: a case including a rear wall, a mounting section attached to said rear wall for mounting the heater assembly in a supporting structure, said case including a front wall formed with an air outlet near the top thereof and an air inlet near the bottom thereof, a back pan spaced from said rear wall and h-aving a skewed portion extending toward the front wall, insulating means disposed between said back pan and said rear wall, a front pan supported in spaced relation with said back pan todefine a low temperature heating chamber, thermostatic means disposed in the skewed portion of said back pan for preventing the temperature in low temperature heating chamber from exceeding predetermined limits, said front pan and at least a portion of said front wall defining a high temperature heating chamber therebetween, said low and high temperature heating chambers communicating with said air outlet to discharge air therethrough, electrical blower means located near the bottom of said low and high temperature heating chambers for circulating air through said high and low temperature chambers, said blower means having an air inlet disposed for communication with the air inlet in said front wall, an electrical heating means disposed within said high temperature heating chamber for heating the air circulating therethrough, and temperature responsive means located adjacent to the air inlet of said blower means for de-energizing said electrical heating means when the temperature at the inlet of said blower means reaches a predetermined level below the predetermined limits, said thermostatic means de-energizing said electrical heating means when said p-redetermined limits are reached.

References Cited UNITED STATES PATENTS 1,945,815 2/1934 Landerman 219-362 X 1,982,139 11/1934 Kercher 219-367 2,007,102 7/1935 Wallace -126 2,815,431 12/1957 Paley 219365 X 2,988,626 6/1961 Buttner 219-367 FOREIGN PATENTS 911,153 11/1962 Great Britain.

ANTHONY BARTIS, Primary Examiner.

Claims

1. A HEATER ASSEMBLY COMPRISING: A CASING INCLUDING A REAR WALL, AND A FRONT WALL AN AIR OUTLET AND AN AIR INLET, A BACK PAN SUPPORTED IN SPACED RELATION TO SAID REAR WALL, SAID BACK PAN HAVING A SKEWED PORTION EXTENDING AT THE TOP TOWARD SAID FRONT WALL, A FRONT PAN SUPPORTED ON SAID REAR WALL AND IN SPACED APART RELATION WITH SAID BACK PAN TO DEFINE A LOW TEMPERATURE HEATING CHAMBER THEREBETWEEN, SAID FRONT PAN HAVING A SKEWED PORTION AT THE TOP EXTENDING TOWARD THE FRONT WALL AND DEFINING A HIGH TEMPERATURE HEATING CHAMBER BETWEEN SAID FRONT WALL AND SAID FRONT PAN, A PLURALITY OF ELECTRICAL RESISTANCE HEATING ELELENTS DISPOSED IN SAID HIGH TEMPERATURE HEATING CHAMBER, MEANS FOR ENERGIZING SAID ELECTRIC RESISTANCE HEATING ELEMENTS FROM AN ALTERNATING SOURCE, MEANS FOR CIRCULATING AIR THROUGH SAID HIGH AND LOW TEMPERATURE CHAMBERS, A STONE TRAY SUPPORTED AT THE FRONT WALL OF SAID CASE AND ADJACENT TO AT LEAST A PORTION OF SAID OUTLET OPENING TO ALLOW HEATED AIR DISCHARGING FROM AT LEAST A PORTION OF THE AIR OUTLET TO PASS INTO THE STONE TRAY, AND MEANS DISPOSED IN SAID LOW TEMPERATURE HEATING CHAMBER AND RESPONSIVE TO THE TEMPERATURE IN SAID LOW TEMPERATURE HEATING CHAMBER FOR PREVENTING THE TEMPERATURE OF THE AIR IN SAID LOW TEMPERATURE HEATING CHAMBER FROM EXCEEDING PREDETERMINED LIMITS BY DEENERGIZING SAID HEATING ELEMENTS WHEN SAID PREDETERMINED LIMITS ARE REACHED.