US2964034A - Hermetically sealed heaters - Google Patents

Description

Dec. 13, 1960 L. E. NORDHOLT ET AL 2,964,034

HERMEITICALLY SEALED HEATERS Filed Dec. 51, 1956 6 Sheets-Sheet 1 Fig.4.

Dec. 13, 1960 E. NORDHOLT ETAL 2,964,034

HERMETICALLY SEALED HEATERS 6 Sheets-Sheet 5 Filed Dec. 31. 1956 FIG. 15.

nyvENToRs LOUIS E.-NORDHOLT RICHARD M. SCHERER ATTORNEYS FIG. 14.

Dec. '13, 1960 E. NORDHOLT ET AL 2,964,034

HERMEITICALLY SEALED HEATERS 6 Sheets-Sheet 4 Filed Dec. 31, 1956 LOUIS E. NORDHOLT RICHAR D M. SCHE R ER Wfiflb Mm ATTORNEYS Dec. 13, 1960 L. E. NORDHOLT ET AL 2,964,034

- HERMETICALLY SEALED HEATERS Filed Dec. 31, 1956 6 Sheets-Sheet 5 FIG. 1].

INVENTORS LOUIS E.NORDHOLT RICHARD M. SCHERER ATTORNEYS L. E. NORDHOLT ET AL HERMETICALLY SEALED HEATERS Dec. 13, 1960 6 Sheets-Sheet 6 Filed Dec. 31. 1956 INVENTORS LOUIS E. N ORDHOLT R I CHA RD M. S OH E R E R W ATTORNEYS United States Fatent O The present invention relates to heaters and particularly to gaseous fuel burning space heaters having a combustion system hermetically sealed with respect to the space or room to be heated.

So-called hermetically sealed heaters are characterized by a combustion system communicating with the exterior of the building only and being isolated from .the air in the room to be heated. Su'ch heaters have numerous advantages over other types of heaters, such as: assuring no contamination of the air in the room by combustion products; using only outside air for combus- '.tion purposes; and preventing the escape er any gaseous fuel into the room, should combustion be accidentally 'or inadvertently terminated while the fuel flow continues. Due to the nature of 'the combustion system of these rheaters', it has been found to be highly desirable, if not necessary from 'a practical "standpoint, to mount them "on the inside -of an'eX'ter-nal building wall so that the outside -venting system for the combustion chamber may be iarianged in close proximity'to the combustion chamber itself. In this regard, the proximity of the combustion chamber to the building wallhas in some cases presented serious fire hazards as well as construction or mounting problems.

A further disadvantage of sealed heaters is that slight changes in external wind velocity and conditions are readily transmitted directly to the combustion chamber through either the combustion air inlet or the combus- 'tion products outlet of the venting system, so that unless the combustion air inlet and combustion products outlet are provided with means compensating for such wind changes, an undesirable pressure unbalance may 'be created in the combustion system tending to impair heater operation and in some cases blowing out the flame at the burner.

It is a principal object of the invention to provide a novel wall-mounted, hermetically sealed heater overcoming the foregoing as well as other disadvantages of prior art sealed heaters.

A more specific object resides in the provision of a novel cabinet and wall mounting structure for sealed heaters particularly useful for preventing overheating of the cabinet and the building wall on which the heater is mounted.

Another object is to provide a hermetically sealed heater including a novel arrangement of natural and forced convection air passageways for circulation of room air whereby heated room air will be simultaneously and advantageously discharged from the heater adjacent the door level of the room and also at a level disposed thereabove.

An additional object is to provide a novel wall mounting structure for sealed heaters facilitating the installation of such heaters adjacent an exterior building wall and obviating the necessity of making any preliminary expensive or time-consuming alterations to the wall.

Yet another object is to provide an external venting Patented Dec. 13, 1960 2 means for concentric combustion air inlet and exhaust gas conduits associated with a sealed combustion chamber insuring proper and desired flow through the combustion system.

Further objects and advantages of the invention will be in .part obvious and in part pointed out hereinafter.

The novel features ofthe invention may best be made clear from the followingdescription and accompanying drawings in which:

Figure l is a top plan view of a-heater of the invention shown attachedto a building wall, the latterbeing in horizontal section;

Figure 2 is a front elevational view of the heater in Figure 1 with the building wall shown fragmenta-rily;

Figure 3 is a side elevational view of the heater of Figure 1 with the building wall shown in vertical section;

Figure-4 is an enlarged elevational view 'of the outside venting means for the heater of Figure 1; I

Figure 5 is an enlarged side elevational view of the heater of Figure 1, with certain parts thereof broken away and other .parts in section;

Figure 6 'is an enlarged fragmentary sectional view taken along line 6-6 of Figure 1;

Figure 7 is an enlarged sectional view taken along line 77 of Figure 1;

Figure 8 is an enlarged, fragmentary, horizontal, sectional view taken generally along line 88 of Figure 2;

Figure 9 is an enlarged sectional 'view of certain parts 'of the heater taken along line 99 of Figure 2;

Figure 10 is-a front elevational view of the parts shown in Figure9, with some of them broken away and others in section;

Figure 11 is 'a front elevational view 'of the parts of Figure 9 on a slightly reduced scale and partially cut away;

Figure 12 is an enlarged fragmentary front elevational view of a preferred embodiment ofthe burner structure of the invention, and showing an exemplary form-0f mounting means for the burner;

Figure 13 is an end elevational view of the burner of Figure 12; I

Figure 14 is an enlarged sectional view taken along line 1414 of Figure 12;

Figure 15 is an enlarged sectional view taken along line 15-15 of Figure 12;

Figure 16 is a vertical sectional view corresponding to Figure 14 but illustrating a modification of this part of the burner;

Figure 17 is a front elevational view of a preferred form of mounting box for the heater;

Figure 18 is a side elevational view 'of the mounting box of Figure 17;

Figure 19 is a top plan view of the mounting box of Figure 17 partially broken away and in section;

Figure 20 is a fragmentary rear elevational view 'of the mounting box of Figure 17, partially broken away; and

Figure 21 is an enlarged, fragmentary, side elevational view of a preferred form of forced air circulating means for the heater.

Referring now to the drawings, a heater'20 embodying the invention (Figures 1, 3, 5) is adapted to be mounted against a building wall 22 above the floor 24 of the room to be heated. The heater 20 preferably includes an internal combustion heating unit 26 (Figure 5) hermetically sealed from the room in which the heater is arranged and including a venting structure extending through a hole 28 in the wall 22 to the exterior of the building for establishing communication between the combustion chamber and the outside atmosphere.

The heater 20 includes a mounting box 'or combination mounting and shielding structure 30 (Figure 5.) adapted 3, to be attached to the inner surface of the building wall 22 to receive the heating unit 26. A cabinet or outer decorative shell 32 encloses the heating unit 26 and is provided with suitable openings for the circulation of room air through the heater.

The mounting box 30, as best seen in Figures 5, 8, and 17 to 20, preferably includes back 34, side 36, bottom 38, and inclined top 40 walls. The back wall 34 is formed with an upper aperture 42 therein for alignment with the building wall hole 28. The side walls 36 preferably extend a greater distance forwardly from the back wall 34 than the bottom 38 and top 40 walls and the upper ends of these side walls are bent in slightly. The top wall 40 preferably inclines upwardly and forwardly from the back wall 34 to the top of the side walls 36. A pair of vertically extending channel-shaped brackets 44 preferably are utilized for attaching the mounting box 30 to the building wall. These brackets 44 are laterally spaced so as to be adjacent each end of the mounting box and may be welded thereto. Brackets 44 may be secured to the building wall 22 by suitable fasteners such as screws 46 extending through holes provided at the upper and lower ends thereof into the wall whereby the back wall 34 will be in spaced, parallel relation to wall 22. A vertical notch or cut-out 48 is provided at the rear upper end of each bracket 44 for a purpose to be set forth hereinbelow.

The heating unit 26 (Figures 5, 8, and 9) preferably includes a hollow combined combustion chamber and heat exchanger 50 and an air box or plenum chamber 52 rearwardly spaced therefrom and generally parallel thereto. A burner 54 is arranged in the lower part of the heat exchanger 50 which defines the combustion chamber. The combustion chamber preferably communicates with the air box through laterally spaced clucts 56 and the air box and heat exchanger communicate with the atmosphere through concentric conduits 58, 60 adapted to extend through aperture 42 in mounting box 34 and be disposed within the hole 28 of the building wall.

The heat exchanger 50 may be constructed of mated front 62 and rear 64 portions suitably connected as by welding of the peripheral flanges 66 thereon and the combustion chamber portion thereof preferably is of generally rectangular box-like configuration. An elongated horizontal opening 68 (Figure 11) is formed in the lower portion of the front section 62 through which the burner 54 may be inserted or removed, and this opening is surrounded by a ridge 70 (Figure 9) cooperating with a complementarily shaped perimetrical groove 72 on a cover plate 74 for closing this opening. This cover plate 74 may be conveniently secured to the heat exchanger 50 by means of spaced, vertical channel strips 76 attached thereto and fastened as by metal screws (not shown) to cooperating-pairs of upper and lower brackets 78 on the heat exchanger. A sealing strip or gasket may be provided in the cover plate groove 72 for sealing engagement with the ridge 70.

The central portion of the mating sections 62, 64 of the heat exchanger preferably converge inwardly and upwardly from the combustion chamber (Figure and are inwardly deformed or grooved throughout a fiat V-shaped outline at 80 adjacent their upper ends for contact with each other to present a battle surface diverging upwardly and laterally (Figures and 11) within the heat ex- -changer below the upper end thereof. The grooves defining this baffle surface terminate laterally inwardly of the side walls of the heat exchanger, and upwardly extending passageways 82 are formed adjacent each side of the heat exchanger. The upper ends of the heat exchanger sections 62, 64 define a chamber communicating with these passageways 82, and the rear section 64 is provided with central aperture 84 above the groove 80 -therein for escape of the combustion products from the .heat exchanger.

The air box52 may be formed of convex mating sections 86, 88 joined together as by welding of peripheral flanges 89. The front section 86 is formed with an upper aperture therein aligned with the aperture 84 in the heat exchanger and the rear section 88 also is formed with an aperture therein, preferably coaxial with the aperture in section 86 but of a larger diameter. A conduit 90 is suitably mounted in the aperture 84 of the heat exchanger and extends through the aligned upper apertures of the air box for engagement to a collar-type fitting 92 connected to the inner concentric conduit 58 (as best seen in Figure 5). The inner end of outer concentric conduit 60 is sealingly engaged to a collar fitting 94 which in turn is attached to the rear section 88 of the air box in surrounding relationship to the upper aperture therein and also being fitting in the upper aperture 42 in the mounting box 30. Suitable structure is provided for attaching the air box 52 to the mounting box. Such structure may include upper and lower pairs of spaced brackets 96 attached to mounting box rear wall 34 (Figures 5 and 17) and to which the upper and lower portion of the air box peripheral flange 89 may be fastened by screws 97 whereby the air box will be in spaced, parallel relation to the rear wall 34 while the vertical portions of the heat exchanger flange 66 are disposed adjacent the outer edges of the mounting box side walls 36 (Figures 8, 9).

A radiation shield 98 preferably is arranged intermediate the air box 52 and heat exchanger 50 as by attachment to the air box flange 89 through spacers 100 (Figures 8 and 9) welded to such flange and also to a similarly positioned flange on the shield 98.

The hole 28 in the building wall preferably is protected by a wall seal arrangement (Figures 5 and 8) including a circular tube 102 disposed therein. The tube 102 preferably has an inturned lateral flange 104 at its inner end to which a plate 106 may be attached, the plate 106 being fastened to the inside of the building wall 22 by suitable fasteners (not shown). Longitudinally extending spacers 108 of L-shaped cross-sectional configuration may be provided at spaced intervals about the circumference of the tube 102 for engagement with the surface defining hole 28. Tube 102 encloses the concentric conduits 58, 60 and is radially spaced from outer conduit 60 while being of an axial length approximately equal to the thickness of the building wall. The space defined between the tube 102 and outer concentric conduit 60 opens at its inner end into the space defined between the inner surface of wall 22 and the back wall 34 of the mounting box.

The annular space between the concentric conduits 58, 60 will be seen to communicate at its outer end with the atmosphere and its inner end with the air box 52, lower ducts 56, and combustion chamber, while the inner conduit 58 communicates at its outer end with the atmosphere and at its inner end with the upper end of the heat exchanger through the associated fitting 92 and duct 90. The outer conduit 60 preferably terminates at the outer face of wall 22, whereas the inner conduit 58 extends outwardly of wall 22. As will be evident, the combustion supporting air will flow in the annular space between these concentric conduits to the air box and thence into the combustion chamber, while the combustion products or flue gases will flow through the inner concentric conduit 58 from the upper end of heat exchanger 50 to the atmosphere.

Variations in external wind velo-citieshave caused serious difliculties in conventional sealed heaters by impair ing flow in the combustion system, and in some cases even extinguishing the burner flame. The invention contemplates the provision of novel venting structure at the outer ends of the concentric ducts 58, 60 for eifecting desired combustion characteristics at all times during heater operation, irrespective of external wind conditions. A preferred embodiment of this venting structure 110 for the combustion system includes a directional baffle arrangement 112 for the inner conduit. 58 and an apertured tubular sleeve 114 for the outer conduit 60 and defining the inlet for combustion air. The tubular sleeve outer concentric conduits.

ages-ana 114 preferably is in the form of a screen or-other'p'erforated structure and is fitted at its inner end into an annular flange 116 inturned from a mounting plate 118. This plate 118 is adapted to be suitably connected to the outer surface of wall 22 as by screws or nails with its inturned flange 116 secured within the outer end of outer concentric conduit 60. An annular groove 120 may be formed adjacent the outer periphery of plate 118 for the reception of caulking material or a sealing ring engageable with the building wall.

The directional baifle arrangement 112, as best seen in Figures and 6, preferably includes an inner, dishshaped member 122 having a central inturned flange 124 fitted within the outer end of the inner concentric conduit 58 and also includes an outwardly and rearwardly flaring convex surface extending from the flange 124 to a vertical peripheral lip 126. The tubular sleeve 114 is in spaced enclosing relationship to the outer end of inner conduit 58, extending to a point adjacent the dish-shaped member 122 and is fitted in an ou-tturned flange 128 of a circular plate 130 connected to the peripheral lip 126 of the dish-shaped member, as by bolts 127 (see Figure 8).

Afiysuitable sealing and cementing material 132 may be applied in the V-shaped peripheral area defined between the dish-shaped member 122 and the outer end of inner conduit '58. A closure cap 134 is arranged outwardly of the dish-shaped member 122 and including an imperforate flat central portion and an outwardly and a rearwardly flaring surface parallel to the corresponding surface of member 122 and also terminating in a fiat peripheral lip 136. A plurality of baffles 138, 140 are arranged intermediate the cap 134 and member 122. Each of these intermediate baffles includes a central aperture 142 aligned with the outlet of inner conduit 58, and a r'earwa'rdly flaring surface complementary to the corresponding surfaces of the cap 134 and member 122 and also terminating in a similar corresponding peripheral lip 144. The intermediate bafiles and the closure cap may be secured in spaced relationship to dish-shaped member 122 as by means of tubular spacer elements 146 encircling coaxial apertures in the peripheral lips of these members and rivets 148 inserted through these spacers and the peripheral lips as seen in Figure 6. Such a connecting structure may be disposed at any desired number of points along the circumference of the aligned peripheral lips for providing a desired strong connection.

Intermediate baffles 138, 140 define with the closure cap 134 and dish-shaped member 122 as well as with each other, generally radially extending passageways of uniform width for discharge of the products of combustion from the inner concentric conduit 58 to the atmosphere in a generally radial direction. Any gusts of wind flowing in a direction normal to and toward the baflie arrangement 112 would be positively prevented from entering the heat exchanger either through the inner or External air for combustion supporting purposes will pass through the tubular sleeve 114 in a radial direction only inasmuch as the spaced plates 118, 130 define a radially extending inlet passageway therefor, this passageway being of uniform width. The air inlet at the tubular sleeve 114, therefore, as well as the combustion products outlet at the outer end of conduit 58 will be seen to be fully protected from any wind currents flowing axially toward conduits 58, 60. If desired, although not necessary, the lip 126 on member 122 may be extended radially outwardly.

It will be appreciated that irrespective of the direction of external wind flow, the directional bafiie arrangement 112 will effect an aspiration of the combustion products through the inner concentric conduit 58 for facilitating the desired directional flow through the combustion system. This novel venting structure for the heater has been found to be highly satisfactory in establishing and maintaining desired combustion characterd istics notwithstanding severe changes inextc'rnal wind conditions. r

The burner 54 preferably is constructed with an elongated burner head 150 (Figures 10 and 12) having the usual longitudinally spaced transverse flame slots v152 therein and including an integral, generally horizontal tubular stem portion 154 communicating at one end with the central portion of head 150 through a slotted inner passageway 156 (Figure 15 The tubular stern 154 includes a Venturi section 158 disposed adjacent the outer free end thereof, the latter end being enlarged and including a 'cut out area 160 defining a primary air inlet. A gas manifold pipe fitting 162 is arranged in an aperture in a web 164 at the enlarged end in the tubular stem and is adapted to discharge gaseous fuel thereinto. This fitting 162 may be in the form of an elbow joint having a base 163 attached to the bottom of heat exchanger 50 (Figures 10 and 13) for communication with a gas manifold pipe (not shown) extending through a suitable aperture in the heat exchanger bottom wall. The flow of fuel through the Venturi section 158 will increase the amount of primary air normally induced to flow into the stem 154 through the inlet 160 by reason of the flow of fuel at the inlet. A primary fuel-air mixing will thus take place before the fuel discharges from the burner. In some instances, it is desirable to vary or adjust the fuel-air ratio within the burner 54. To facilitate such adjustment, a generally radially outwardly extending lug 166 is formed adjacent the Venturi section 158 (Figure 14). This lug 166 is provided with a longitudinally extending tapped bore opening into the Venturi throat and into which a screw 168 may be threaded. The outer end of screw 168 has the usual groove or kerf-17t) therein, While the inner end is formed with a conical tip172. Rotation of this screw by an appropriate tool will be effective to variably project the inner end 172 thereof within the throat of the Venturi, thereby offering greater or lesser resistance to flow through the stem 154. Such variable flow resistance operates to vary the amount of primary air induced into the stem 154 in proportionto the amount of gas flowing therein whereby the fuel-air ratio will be correspondingly varied.

A lug 174 preferably is arranged at the left end of the burner head 150 (as viewed in Figures 9 and 10) for engagement toa bracket 176 attached to the innersurface of the left side wall of heat exchanger-50.- This lug and bracket arrangement cooperates with the fitting 162 to support the burner within the heat exchanger (Figures 9, 10, and 12). Lug 174 preferably extends outwardly and then downwardly from the burner head and is integral therewith, while the bracket 176 is hollow and slotted to receive the lug whereby the burner may be conveniently mounted in desired position in the heat exchanger by engaging the lug to the bracket and by engaging the Web 164 of stem 154 to the fitting 162. The coverplate 74 for the heat exchanger opening '68 may be formed with a suitable aperture (not shown) adapted to be aligned with the outer end of burner adjusting screw 168 for insertion of the adjusting tool. This aperture in the cover plate may be hermetically sealed by a removable plug or the like (not shown).

If desired, lug 166 on the burner tubular stern 154 may be formed to extend radially downwardly from the Venturi section rather than upwardly, as lug 178 in Figure 1'6, and a pin 180 may be slidably arranged in this lug. Pin 180 also includes a conical inner end182 and an outer head 184 biased by leaf spring 186 against an adjusting screw 188, the latter screw being threadedly engaged to nut 190 and extending through the bottom of the heat exchanger front section 62 for convenient external adjustment.

The gas manifold pipe connected to fitting 162 communicates with and is connected to the usual gas supply conduits and room thermostatic controls (not shown) for automatic control of fuel flow. A pilot burner Qr other suitable main burner ignition device may be conveniently arranged within the heat exchanger 50 adjacent the burner head 150. As seen in Figure 10, a conventional pilot burner 192 and thermocouple 193 arrangement may be attached to and extend through a horizontal ledge 194 formed by recessing the lower front portion of the heat exchanger at 196.

The heat exchanger cover plate 74- preferably is formed with a transparent disc 198 of suitable heat-resisting material for external visual observation of the pilot burner flame. This disc 198 may be in the form of a cap removably fitted to cover an opening in the cover plate 7 4 whereby an igniting means may be inserted therethrough for lighting the pilot burner.

The vertical portions of the heat exchanger peripheral flange 66 cooperate with the adjacent outer edges of the mounting box side walls 36 to define a space opened at the upper and lower ends thereof for circulation of room air in heat exchange relationship with the various parts of the heating unit in this space, namely the rear section of the heat exchanger, the radiation shield 98 and the air box 52. A means for effecting a forced downward circulation of air through this space may be provided, whereby heated air will be discharged adjacent the floor 24 of the room to be heated. For this purpose, an angulated fitting 200 (Figures 8, 9, and 17) preferably is arranged in the left corner of mounting box 30 and is attached to the back wall 34 and left side wall 36 thereof, functioning with these latter walls as an upwardly extending duct. The right side wall 202 of the angulated fitting 200 extends downwardly beyond the front wall 204 thereof to the bottom wall 38 of the mounting box and defines a lower opening for the duct, which is also opened at its upper end, the latter preferably being disposed adjacent the horizontal central line of the mounting box.

An apertured plate 206 (Figures 18, 19) is arranged adjacent the lower portion of the side wall 202 and may be suitably connected in vertical position thereto as by welding. This plate 206 extends perpendicularly outwardly from the mounting box back wall 34- to a position forward of the outer edges of the side walls 36 and preferably is reversely bent forwardly at its back edge for receiving the inner or back edge of a similarly apertured plate 208 similarly arranged and suitably connected to a blower housing 210. A conventional horizontal axis, impeller-type blower (not shown) is journaled in the housing 210 and receives power from a suitable source such as prime mover 212. An upper tangential outlet duct 214 extends from the blower housing while the left blower housing side wall (Figures 10 and 11) is formed with an inlet opening aligned with the apertures in the plates 206, 208 constituting the axial inlet for the blower. The lower opening in the fitting 200, as well as the apertures in plates 206, 208 and the blower inlet may be enclosed by a fitting 216. This fitting 216 is suitably connected to the adjacent fitting 200, plate 206, and the mounting box and may be formed with an outer surface flaring horizontally outwardly from the left side wall 36 of the mounting box. Thus, the blower inlet will be in communication with the space in the heater through the opened upper end of fitting 200.

After the mounting box and heating unit have been installed in desired position adjacent the building wall 22, the cabinet 32 is fitted over these parts. The cabinet 32 preferably includes interconnected side 218, top 220, and bottom 224 pieces (Figures 1 to 3, 5 and 8) of sheet metal construction. The rear edges of the side pieces 218 preferably are turned inwardly for desirable engagement.

with the building wall 22 while the front edges thereof may be turned inwardly and rearwardly for facilitating attachment to the side walls 226 of the top piece 220. The top piece 220 extends from the top of the cabinet downwardly to a position intermediate the height thereof and the upper part of this piece is conveniently attached to.

the upper ends of the side pieces 218. Top'piece 2 20 terminates in a downwardly turned lip or flange 228 at its extreme rear upper end. This downturned lip 228 is conveniently disposed in the notches 48 at the upper ends of the channel brackets 44 attached to the mounting box. By reason of this arrangement, attachment and removal of the cabinet 32 is greatly facilitated. However, additional supporting means for retaining the cabinet in position may be provided.

The bottom cabinet piece 224 may be formed with an tip-turned lip 230 at its rear end for engagement with the building wall and is conveniently attached to the bottom of the side pieces 218. The cabinet further includes lower front piece 232 attached to the bottom piece and engaging the top and side pieces to completely enclose the space within the heater. The top 220 and lower 232 pieces preferably extend in generally converging directions from the upper and lower ends of the cabinet respectively to define a forward disposed space or passageway in the heater for the passage of room air to be heated. These pieces 220, 232 are provided with suitable grilles constituting room air inlets and outlets for the heater. These grille openings are indicated by numeral 234 for the lower front piece 232, while the top piece 220 preferably'is formed with a relatively large central opening therein in which a curved perforated member or grille 236 may be disposed. The upper end of top piece 220 may be provided with additional openings 238 communicating with the space defined between the mounting box back wall 34' and the building wall, or the member 236 may be constructed and arranged to extend to this part of the top piece and communicate with said space.

The lower front piece 232 may be suitably hinged at its bottom to the front edge of the bottom piece 224 and retained in closed position by engagement of a spring latch detent 240 with the bottom of top piece 220. Manually operable controls (not shown) may be arranged within the lower part of the heater, and access will be afforded to them through the hinged front piece 232. An outer hand grip portion 242 (Figures 2 and 5) may be provided at the upper end of front piece 232, protected by a heat shield 244.

To furnish additional support for the cabinet 32, inwardly extending horizontal brackets 246 may be attached to the side pieces 218 (Figure 8) for convenient connection as by screws (not shown) to the heat exchanger peripheral flange 66. Also, the upper end of the cabinet top piece 220 may be constructed and arranged so that it rests on the top of the mounting box 30 when the former is fitted over the heating unit.

It should be noted that the cabinet side pieces 218 are spaced outwardly from the parallel side walls 36 of the mounting box, whereby an air jacket for the side and rear of the heating unit is provided. This jacket communicates with the lower portion of the heater since the mounting box side and rear walls terminate above the bottom cabinet piece, the latter preferably being disposed above the room floor 24.

Operation of the heater will now be described. Fuel will flow to the main burner, for ignition by the pilot burner, in response to a demand for heat in theroom or zone to be heated sensed by the thermostatic control means positioned therein. Combustion of the fuel in the heat exchanger 50 will produce an upward flow of combustion products through the heat exchanger and inner conduit 58 to be discharged to atmosphere through the baffie arrangement 112. This how of combustion gases will induce an inward flow of external combustionsupporting air into the combustion chamber through the inlet sleeve 114, the annular space between concentric conduits 58, 60, air box 52, and lower ducts 56. As the hot combustion gases rise in the heat exchanger, the walls thereof are heated, increasing the temperature of the surrounding air and thereby inducing a natural upward convection flow of room air into the bottom of the heater and out the top thereof through the cabinet 32.

The convergence of the intermediate wall sections of the heat exchanger 50 compensates for the reduction in volume of the hot combustion gases occasioned by the transfer of heat to the vertically rising room air in the heater, and the V-shaped baffle surface defined by the cooperating grooves 80 in the heat exchanger produces desirable flow of the hot gases for assuring efficient heat transfer before such gases discharge from the heater. The radiation shield 98 will be efiective to prevent undesirable heating of the air box and mounting box rear wall by radiation from the heat exchanger.

It will be noted that during the natural convection flow of room air through the heater, some air will enter the bottom of the air jacket surrounding the mounting box 30 and rise upwardly therein for discharge through the top cabinet piece 220. The air jacket will thereby prevent overheating of the building wall as well as the cabinet, and moreover, some of this air will flow in the annular space between outer conduit 60 and tube 102 to minimize the heat transferred to the building wall in this region. If desired, insulation may be placed in this annular space and also in the space surrounding tube 102 for the same purpose.

An important advantage of the heater of the invention is the heating eifect realized by operation of the blower in housing 210. Operation of this blower may be controlled by temperature responsive means positioned within the heater itself so that in the event the temperature within the heater becomes sufficiently high, the blower will be auomatically turned on and pull downwardly some of the air rising in the rear space formed between mounting box and the heat exchanger. This downwardly drawn air flows through the fittings 200, 216 and into the blower housing 210 to be discharged by the blower through tangential outlet duct 214 for subsequent generally horizontal flow through the grille in the front cabinet piece 232 at a level adjacent the floor. Thus, heated air will be discharged from the heater simultaneously from the top and bottom thereof for eflicient heating. As will be understood, the displacement of the blower may be varied in accordance with the desired operating characteristics so that more or less air will be pulled downwardly through the heater. Additionally, other blowers may be similarly arranged at other positions in the mounting box, such as in the lower right corner thereof, for increasing the downwardly forced air circulation in the heater.

The external combustion-supporting air flowing through outer duct 60 and air box 52 will not be undesirably preheated inasmuch as the distance it travels in contact with the hot inner conduit 58 is not very great, and the temperature of the air box will be kept relatively low by the shield 98. However, a tubular insulating collar (not shown) may be fitted around the inner conduit 58 for this purpose.

As previously noted, the burner 54 may be conveniently attached to and removed from the heat exchanger, and access for adjustment of the fuel-air ratio will be offered simply by opening the cabinet front piece 232.

It will thus be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiment has been shown and described only for the purpose of illustrating the principles of the invention and is subject to extensive change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the appended claims.

We claim:

1. In a wall mounted space heater; a heating unit adapted to be mounted adjacent a wall, a cabinet adapted to cooperate with the wall for enclosing said heating unit, a mounting box adapted to be disposed intermediate said heating unit and the wall and define an air jacket directly with the wall and said cabinet, said cabinet having upper and lower openings for upward convection flow of room air in heat exchange relationship with said heating unit, a separate wall member attached to laterally spaced regions of said mounting box and on the same side of said mounting box as said heating unit, said wall member being spaced from the portion of said mounting box between said regions so as to form therewith a duct means having an upper inlet and a lower outlet, and a blower operatively secured to the lower end of said duct means for inducing a downward flow through said duct means of some of the air rising in said heater and discharging such air adjacent the floor of the room.

2. The structure defined in claim 1 wherein the mounting box includes back and side walls, said back wall adapted to be disposed parallel to the room wall, brackets on said back wall adapted to attach it to the room wall; and wherein the cabinet includes means cooperating with said brackets for releasably retaining said cabinet in enclosing relation with respect to said heating unit.

3. The structure defined in claim 2 wherein the means included by the cabinet includes a top wall having a depending flange, and said brackets having notches therein for engagement by said flange.

4. A combined combustion air inlet and exhaust gas outlet structure adapted to be attached to a wall mounted, hermetically sealed heater having concentric conduits connected to a heat exchanger and extending through the wall on which the heater is mounted: said structure including: a mounting plate adapted to be attached to the outside of the building wall and having a central aperture therein defined by an inturned flange engageably secured to the outer concentric conduit; a dish-shaped member arranged outwardly of said mounting plate and having a convex central portion provided with an aperture at its apex, said aperture being defined by an inturned flange engageably secured to said inner conduit; means attached to the periphery of said dish-shaped member and disposed parallel to said mounting plate to provide a peripheral inlet of substantially constant width for said outer con centric conduit; an apertured sleeve connecting said mounting plate to said last-named means, one end of said sleeve being secured to the inturned flange of said mounting plate; a generally dish-shaped cap for said inner concentric conduit spaced axially outwardly of said dish shaped member and connected thereto; and at least one batfie disposed intermediate said cap and said member and defining therewith generally radial passageways of substantially uniform width communicating with said inner conduit.

5. The structure defined in claim 4 wherein the means attached to the periphery of the dish-shaped member has an outturned flange defining a central aperture concentric with and substantially equal in diameter to the aperture in the mounting plate, and wherein the other end of the apertured sleeve is secured to said outturned flange.

References Cited in the file of this patent UNITED STATES PATENTS 100,268 DeLandsee Mar. 1, 1870 687,668 Taylor Nov. 26, 1901 1,674,643 Hartwig June 26, 1928 2,160,883 Lundstrum June 6, 1939 2,192,920 Linch Mar. 12, 1940 2,241,025 Wedderspoon May 6, 1941 2,243,916 Mueller June 3, 1941 2,632,435 Lundstrum Mar. 24, 1953 2,671,500 Jones Mar. 9, 1954 2,692,186 Reznor Mar. 9, 1954 2,755,794 Wendell July 24, 1956 2,764,972 Ryder Oct. 2, 1956 2,818,059 Cayot Dec. 31, 1957 FOREIGN PATENTS 736,326 Great Britain Sept. 7, 1955

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