Electric heating and air circulating unit

Nov. 15, 1955 g. j. Campbell 2,724,044

ELECTRIC HEATING AND AIR CIRCULATING UNIT

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WO 6

Nov. 15, 1955

G. J. CAMPBELL

2,724,044

ELECTRIC HEATING AND AIR CIRCULATING UNIT

Filed May 29, 1953

Sheets-Sheet 2

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2,724,044

Patented Nov. 15, 1955

United States Patent Office

2,724,044

ELECTRIC HEATING AND AIR CIRCULATING

UNIT β

Gregory 3. Campbell, Freeport, BL, assignor to St. Joe Machines, Inc., St. Joseph, Mich.

Application May 29,1953, Serial No. 358,427

Claims. (CI. 219—39) ¹⁰

This invention relates to improvements in electric heating and air circulating unit.

The principal objects of this invention are:

First, to provide an inexpensive electric heating and air circulating unit that can be installed between the studding of a wall and thereafter serviced as necessary through air intake and discharge openings and switch box projecting to the surface of the wall.

Second, to provide a novel air heating and circulating unit in which the electric heating element will not operate unless the circulating fan is also operating.

Third, to provide novel means for removably supporting an electrical heating element and an air circulating fan within a conduit mounted within the wall of a room.

Further, to provide a novel control circuit including a novel fusing arrangement which permits an electric heating element to be mounted within an enclosed duct in a wall and independently energized with respect to an air circulating blower without danger of the heating element becoming overheated due to failure of the blower.

Other objects and advantages of the invention will be apparent from a consideration of the following description and claims. The drawings of which there are two sheets illustrate a highly practical form of the invention.

Fig. 1 is a fragmentary perspective view of a portion of a room and wall with the heating unit installed therein.

Fig. 2 is a fragmentary front elevational view of the heating unit partially broken away in vertical cross section.

Fig. 3 is a fragmentary vertical cross sectional view through the heating unit.

Fig. 4 is a schematic wiring diagram of the connections between the electrical elements of the unit.

Fig. 5 is a perspective view of the heating element incorporated in the unit.

Fig. 6 is an enlarged fragmentary cross sectional view through the heating element and its enclosing column and taken along the plane of the line 6—6 in Fig. 5.

Fig. 7 is a fragmentary perspective view of the lower end of the heating unit with an air directing and heating element supporting baffle partially installed therein.

Fig. 8 is a fragmentary cross sectional view through novel fuses employed in the electrical circuit of the unit.

As is indicated in the objects of the invention, the heating unit is adapted to be built into the wall of a room but may be positioned against the wall and projecting into the room if desired. The unit is adapted as will be described to circulate air in the room either with or without the addition of heat to the circulated air. In the drawings the reference numeral 1 indicates the wall of a room. 2 represents the inner surface of a double wall construction spaced rearwardly or outwardly from the inner surface of the wall 1. The heating unit comprises generally an upright tubular column 3 of rectangular cross section adapted to fit within the hollow wall between the wall surface 1 and 2. The column is closed at its ends by end walls 4. The front wall 5 of the column has a forwardly opening inlet port 6 formed therein near its upper end and a forwardly opening discharge port 7 formed in its lower end. Opening 8 is formed in the front wall of the column

GO intermediate of its ends to receive a junction box 9. A blower unit indicated generally at 10 is mounted within the upper end of the column while a heating element 11 is mounted within the lower end of the column above the discharge port 7. A manually controllable switch 12 and a thermostat 13 are mounted on the junction box 9.

An upper throat 14 of rectangular outline has a rear wall 15 that is secured to the front wall of the column and around the inlet port 6 as by screws 16. The rear wall 15 has a rearwardly turned venturi 17 formed thereon and opening into the column. An upper grill 18 is provided with a peripheral flange 19 adapted to fit around and be secured to the throat 14.

The rear wall 15 of the mounting plate has forwardly projecting pins or screws 20 thereon supporting a spider 21 across the front of the venturi 17. Suitable rubber grommets are provided at 22 to yieldingly support the spider. The spider 21 in turn supports an electric motor 23 that projects into the venturi 17 and the upper end of the column. A rotor 24 is secured to the inner end of the shaft of the motor and partially embraces the motor. A spirally disposed baffle plate 25 is positioned in the upper end of the column to form a downwardly facing discharge throat 26 positioned along one side of the column.

The heating element comprises a tubular box like carrier 27 having downwardly tapering end walls 28 and downwardly converging front and back walls 29. Secured to the walls 29 as by bolts 39 are insulating supports 31 for the electrical heating coils 321. The lower edges of the walls 29 are turned forwardly and backwardly in locating flanges 32 and the rear locating flange 32 is provided with downwardly extending ears or lugs 33. The carrier 27 is supported within the column by engagement of the lugs 33 in slits 34 formed in the top horizontal flange of a downwardly and forwardly curved baffle plate 35. With particular reference to Fig. 7, it will be noted that the carrier 27 with its heating elements attached may be forced upwardly in the bottom of the column and the baffle plate 35 thereafter installed until the lugs 33 engage in the slits 34 with the lower curved end of the baffle positioned in the discharge throat 7. The lower grill 181 may then be engaged over the forwardly projecting discharge throat 7. The lower end of the baffle 35 is flanged downwardly and rearwardly to engage under a spring clip 36. The switch box 9 is provided with a laterally extending feed conduit 37 and is conected to upwardly extending conduit 38 and downwardly extending conduit 39. The upper edges of the side walls 29 of the carrier are sloped downwardly and outwardly and are notched as at 40 to space the upper end of the carrier from the walls of the column and permit the circulation of air around the outer sides of the carrier and prevent overheating of the column walls. The downwardly converging position of the two electrical heating elements 31 causes the air to move between converging heating elements for efficient heat transfer.

The circuit for connecting the elements of the heating unit is illustrated in Fig. 4. The conductor 42 forms the grounded side of a 110 volt circuit or the neutral line of a 220 volt 3 wire circuit. When the heating unit is connected for 110 volt operation the current is directed through the fuse 43 and conductor 44 to a thermostat 13. From the thermostat 13 the current is directed to the movable pole 46 of the switch 12 and can be connected through the conductor 47 to the motor 23. Conductor 48 returns the circuit directly to conductor 42. Simultaneously the switch 46 closes on conductor 49 that is connected to one end of a heating coil 50A. The coil 50A is connected in parallel with a second coil 50B by connection of jumpers 51 and 52 that are installed for 110 volt operation. Current is returned through the jumper 52 to

2,724,044 the conductor 42. For operation of the motor 23 without the heating elements 50A and 50B the switch 46 is closed on the terminals 53 to connect the thermostat bridging conductor 54 to the motor.

For 220 volt operation, the jumpers 51 and 52 are removed or disconnected and 110 volt current may be supplied to the motor 23 from the conductor 44 as previously. 220 volt current is supplied through the conductor 55 to the heating element 50B and in series through the element 50A to conductor 49 for return through the switch 46 and thermostat 45. As with the 110 volt circuit the fan can be operated without the heating elements.

In order to protect the heating unit as described above against over heating, the fuse 43 is of special construction and location. As is best illustrated in Figs. 2 and 8, the fuse consists of an insulating base plate 56 secured to the motor support plate 15 and provided with a rearward extension 57 projecting into the discharge throat 26 of the blower. An insulating bar 58 is removably secured to the base 56 by nuts 59 and is provided with a rearward extension 60 projecting through the extension 57. The extension 60 is vertically grooved as at 61 and a thin strip of low melting point fuse metal 62 is wrapped along the sides of the projection 60 and over the groove 61 so as to be fully exposed to the air stream in the throat 26. Terminal plates 63 make contact at the ends of strip 62 for connecting it in series with the previously described conductor 44. The heating elements 50A and 50B combine to create a relatively large load which may be in the neighborhood of 11 amperes. The portion of the fuse strip 62 which bridges the groove 61 is cut or trimmed to have an electrical carrying capacity substantially less than the over load of the heating elements. For example, the fuse may be rated at about 6 amperes when the load is rated at 11 amperes. The fuse strip 62 would automatically burn out or melt if operated under these conditions for a short period of time. However, the location of the fuse strip in the air stream from the blower causes the heat created in the fuse strip to be dissipated before the fuse strip can melt. Should the motor stop for any reason, the air stream is, of course, interrupted and the fuse strip rapidly heats and melts to disconnect the heating elements 50A and 50B.