US2857906A - Space heater - Google Patents

Description

Oct. 28, 1958 W. l.. DAVIDSON Erm. y 2,857,906

SPACEA HEATER Filed Sept. l5. 1954 4 Sheets-Sheet 1 JNVENTOR:

Oct. 28, 1958 w. L. DAvlDsoN TAL 2,857,906

SPACE HEATER 4 Sheets-Sheet 2 Filed Sept. 13, 1954 JNVENTo er anni Hyg/2471120 Pla if' n@ en@ n@ Oct. 28, 1958 Fired sepgc. 13. 1954 w. L. DAVIDSON ErAL 2,857,906

SPACE HEATER A4 Sheets-Sheet C5 -.E=== A m l-l Fil-1 l-l lll IN VEN T0 #er L. DandRJja/r,

Oct. 28, 1958 W. L. DAVIDSON ETAL SPACE` HEATER 4 sheets-sheet 4 Filed Sept. 15, 1954 United States Patent O SPACE HEATER Walter L. Davidson, Allison Park, and Abraham P. Loeb and Morgan P. QLaughlin, Pittsburgh, Pa., assignors to Dravo Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Application September 13, 1954, Serial No. 455,592

1 Claim. (Cl. 126-110) The present invention pertains generally to space heaters of the type which discharge heated air through ducts to the area being heated or of the ductless type wherein the heated air is discharged from the heater directly into the space to be heated by means of adjustable hoods associated with the air outlets of the heater.

More specifically the invention relates to a combination of combustion chamber and convector plenums so related to each other and to the heater casing so as to obtain improved heating eciency, minimum obstruction to the ow of air through the casing and maximum ilexibility in the mounting of the heater within the area to be heated.

Space heaters of the duct type are well known in the art. Many different designs of heaters and arrangements of the component parts thereof have been made in order to increase the efciency of such heaters. Space heaters of the ductless type are relatively new in the art and these heaters in addition to the problem of increased efciency also present additional problems of economy in size and adaptability for mounting in various positions within the area to be heated. The ductless heater by reason of being frequently mounted within a restricted space presents the compound problem of maximum eficiency, minimum space, and maximum flexibility in mounting.

The prior art in an endeavor to obtain increased efliciency provides suggestions for a plurality of passes of the combustion gases through the combustion chamber before discharge to the atmosphere through a suitable stack arrangement. In some instances the prior art also suggests passing the combustion gases exteriorly of the combustion chamber through some form of heat exchange unit to extract additional heat from the combustion gases prioi to discharge from the heater. All such arrangements known to the present inventors produces a rather bulky design of heater in which flow of heating air through the heater is usually impeded causing hot spots in the combustion chamber or heat exchange unit with consequential reduced heating efliciency and accelerated deterioration of those portions of the heater in contact with the combustion gases.

In the present heater, by reason of a novel form of combustion chamber, a plurality of passes of the combustion gases through the chamber are obtained and a maximum exposure of the heated surfaces of the chamber is provided whereby the air to be heated flows freely `over these surfaces with a minimum of obstruction, an

additional heat exchange unit, referred to herein as a convector plenum, is disposed above the top wall of the combustion chamber and in parallel spaced relation thereto so as to provide a plurality of passageway/s between the plenum and combustion chamber, between the plenums and through the plenums for the air flowing past the combustion chamber. We have used heat resistant metal to construct the combustion chamber and ordinary steel to construct theplenums so that these members may be heated to a much higher temperature f'ce than is possible with ordinary steels. The specific design of the chamber and plenums permits control of the distribution of air to be heated passing over, beneath and around the chamber and plenum so as to control the extraction of heat from the metal thus preventing hot spots which accelerate the rate of deterioration of the metal.

One object of the invention is to provide a combination of combustion chamber and convector plenum which offers a minimum obstruction to heating air passing thereover and distributes such air so as to prevent formation of hot spots in the combustion chamber or convector plenum.

Another object of the invention is to provide a novel form of combustion chamber and convector plenum permitting improved extraction of heat from the combustion gases before being discharged from the heater.

A further object of the invention is to provide a novel form of mounting for the combustion chamber within the heater casing permitting free expansion and contraction of the chamber, during heating cycles, while the heater may be mounted in a plurality of diierent positions.

These and other objects will be made apparent as the disclosure proceeds. In the drawings forming part of this disclosure, Fig. l is an isometric view of the heater showing the combustion chamber, convector plenum, blower fan and casing with portions of the casing removed to better illustrate the arrangement of the parts;

Fig. 2 shows a side elevation of the heater of Fig. 1 with portions of the casing and combustion chamber removed to better show the flow of combustion gases through the chamber and plenum;

Fig. 3 shows the rear end elevation of the heater with a portion of the casing removed to better show the arrangement of the combustion chamber and plenum in relation to the casing of the heater,

Fig. 4 shows a side elevation of the heater showing the arrangement of the casing;

Fig. 5 shows in detail a side elevation of the convector plenum;

Fig. 6 shows a rear elevation of the convector plenum;

Fig. 7 shows a section through the plenum taken along the lines VII-VII of Fig. 5;

Fig. 8 shows a section through the plenum taken along the lines VIII-VIII of Fig. 5;

Fig. 9 shows a side elevation of the combustion chamber;

Fig. l0 shows a front elevation of the com'bustion chamber;

Fig. ll shows a rear elevation of the combustion chamber;

Fig. l2 shows a typical corner detail at lines XIl-XII of Fig. 4; and

Fig. 13 shows an enlarged detail of the casing support at lines XlI-XIII of Fig. 3.

Referring now in detail to the drawings, reference character 1 refers in general to the heater having an enclosing casing 2, combustion chamber 3 and convector plenums d connected by a header plenum S. Beneath the co-mbustion chamber is an air baffle pan 6 having an opening 7 therein registering with the outlet of a blower fan 8 secured beneath the baille pan 6 and driven by a suitable motor 9. Above the combustion chamber, a heating air outlet in the casing has suitable hoods associated therewith for directing the heating air in a plurality of directions.

The combustion chamber 3 comprises a front plate 10, side Wall portions 11, bottom wall portions 12 and 13, top wall portions 14 and 15, ,and a rear wall 16. The combustion chamber is of generally hexagonal shape having its longer axis disposed vertically. The chamber is Patented Oct. 28, 1958 preferably made of stainless steel and of welded construction. For convenience in Welding, the front plate and rear wall 16 of the chamber are made slightly larger than the side, top and bottom walls so that all welds can be of the lillet type and on the exterior of the chamber. Each top wall portion 14 and 15 is provided with a suitable opening 17 for passage of combustion gases from the chamber 3 into the plenums 4. These openings 17 are adjacent the front wall of the chamber and are enclosed by a suitable conduit 18 for attachment to the adjacent plenum. In the front wall of the chamber adjacent the lower portion thereof a suitable opening 19 is provided and enclosed by a burner tube 20. Also on the front face of the combustion chamber adjacent the top thereof is an opening 21 enclosed by a tube 22 forming an observation port. Lifting lugs A and B may be provided on the respective front plate 10 and back wall 16 of the combustion chamber for handling the chamber during assembly of the heater, and may also be used for lifting the entire heater.

The convector plenums 23 and 24 are disposed above the combustion chamber top walls 14 and 15 in parallel spaced relation thereto. The plenum 23 is disposed above the top wall 1.4 and the plenum 24 is disposed above the top wall 15. Preferably, the outer side wall of each plenum is disposed in substantially vertical alignment with the adjacent side wall of the combustion chamber, and the inner side wall of the plenum is disposed in spaced relation to the center line of the combustion chamber as shown in Fig. 7. The plenums 23 and 24 thus comprise hollow box-like structures extending from the inner face of the combustion chamber front plate 10, across the combustion chamber and beyond the rear wall 16 thereof. The ends of the plenums, adjacent the rear wall of the combustion chamber, are connected by a header portion 25. The header 25 is comprised of a continuous rear wall 26 spanning the plenums 23 and 24 with side walls 27 extending outwardly from the periphery of rear wall 26 to conform to the slope of the plenum walls and a front wall 28 lling the space between the adjacent plenum walls and extending downward to the peripheral side Wall 27. Adjacent the front wall of the combustion chamber, each bottom wall 29 of the plenum has an opening therein registering with the opening 17 in the combustion chamber and the registering openings are connected by conduits 18 as shown in Figs. 5 and 8. Extending transversely through each plenum is a hollow box-like structure 30 having its top/and bottom walls disposed in spaced relation to the top and bottom walls of the respective plenum and having its side walls disposed in spaced relation to the side walls of the plenum. The ends of the members 30 protrude slightly beyond the vertical faces of the plenum members 23 and 24 as shown in Fig. 7. The member 30 thus provides a passage for heating air through the member 30 and combustion gases owing through the plenum pass around the member 30. The rear face 26 of the header 25 has an opening 31 therein and a conduit 32 mounted on the rear wall of the header in register with the opening 31 provides for exit of the combustion gases from the plenum header to the atmosphere.

Within the casing 2 is a suitable support for the combustion chamber comprising a bottom pan 35 having at the corners thereof members 36 connecting the bottom pan with the baffle pan 6. Adjacent each corner of the bottom pan is a suitable supporting member such as the angle 37 supported on the bottom pan 35 and extending upwardly for connection with the under side of the bafe pan 6 by means of suitable clip members 38. Disposed above the bathe pan 6 are a pair of frame members 39 disposed adjacent the front plate 10 of the combustion chamber and secured thereto. At the rear of the combustion chamber are a pair of members 40 dis- 'posed on opposite sides of the combustion chamber but not attached thereto. The members 39 and 40 on opl with the bottom walls of the combustion chamber so vas to permit the combustion chamber to move relative to the members 42 during expansion and contraction of the chamber'. .Adjacent the upper ends of the members 40 are the -supporting members 43 fastened to one leg of the members 40 and extending upwardly therefrom so as to terminate in a flange 44 disposed beneath the wall 27 of the convector plenum header 25 providing a support for the plenum header upon which the header may move during expansion and contraction of the plenum and header. Adjacent the rear of the combustion chamber is a strap 45 engaging the top of the combustion chamber and extending downwardly along the top walls of the chamber so as to terminate in ange portions 46 overlying and welded to the members 40. This strap member 45 is not connected to the combustion chamber but serves t-o retain the chamber and associated plenum in xed relation to the supports 43 and 42 when the heater is mounted in an inverted position. Each of the members 39 and 40 have secured thereto, in vertically spaced relation, separators 47 having one end secured to the members 39 and 40 as by welding, the opposite end of the members 47 having a plate washer 48 welded to the member 47 to serve as a spacer for the casing members. The separator 47 is provided with internal threads.

The outer casing of the heater may be mounted upon 'y the above described combustion chamber supporting frame in any suitable manner. One method of supporting the casing would be to provide the casing side sheets 50 and 51 with side flanges to which would be secured the rear casing sheet 52 and front casing sheet 53 as ,shown in Fig. 12. Sheet 52 is provided with a suitable opening through which the plenum header conduit 32 extends and the sheet 53 is provided with suitable openings through which the burner tube 20 and observation port tube 22 extend. The side sheets 50 and 51 are provided with suitable lateral supports by means of the anges 54 of the bafe pan 6 and provided with vertical and lateral support by means of stud bolts 55 extending through the casing sheets and threaded into the separators 47 secured to the combustion chamber frame members 39 and 40. The upper ends of the casing sheets 50-51 would conform to the slope of the upper surface of the plenums 23 and 24, being disposed in spaced relation thereto, and joined by a suitable collar 56 extending over and secured thereto. The casing sheets 52--53 would extend vertically upward with their upper ends conforming to the slope of the side sheets 50 and 51 so as to be disposed beneath and connected with the collar 56. Disposed upon the collar 56 is a nozzle pan 57 of suitable design for attachment to the collar and provided with apertures 58 for reception of the air directional nozzles 59. The casing about the combustion chamber when constructed in this manner will have adequate vertical support as well as transverse support supplied by the stud bolts 55 which are anchored in the framing members 39 and 40, and their lower ends secured against lateral displacement by means of the lianges 54 of the baffle pan 6. The portion of the casing about the blower fan is preferably formed of casing members 60 provided with louvers 61 and secured to the bottom pan 35 and bale pan 6. As clearly shown in Figs. 3 and 4 of the drawings the outer casing sheets 50 and 51 are supplied with a suitable bearing by means of the washer plates 48 and may be provided with an additional plate Washer 62 disposed upon the outer face of the casing sheets and beneath the head of the stud bolt 55, as shown in Fig. 13.

Within the casing and adjacent the casing plates 50 51-52-53 are preferably provided heat shields 63. These are preferably of heat resistant metal such as stainless steel and disposed in slight spaced relation to the outer casing sheets, as shown in Fig. 12. These heat shield sheets 63 are preferably provided with side flanges secured to the adjacent casing sheets and at the sides of the casing are provided with suitable openings for passage of the separators 45 which provide vertical support for the casing sheets. As clearly shown in Figs. 3 and 4 of the drawings the upper ends of the heat shields 63 secured to the side sheathing plates 50 and 51 extend upwardly for substantially the full length of the latter sheets and conform to the contour thereof. At the corners of the casing, corner heat shields 63a are provided.

During operation of the heater, it may be mounted upon its base 35 as shown in Fig. 1 of the drawing, or it may be suspended in an inverted position. Where desirable it may be mounted in a horizontal position. When inverted the combustion chamber supporting members 39 and 40 by reason of their connection with the chamber, either directly or through strap 45, retain the chamber in operating position. A suitable burner 64 is mounted in the burner tube 20. Such a burner may be any one of the commercial forms now available and preferably adapted for burning either oil or gas. A fan and limit switch 65 may be provided in the upper portion of the casing and a stack switch 66 may be mounted in the combustion gas outlet conduit 32 for automatic control of the operation of the heater. A suitable control panel 67 may be mounted on the casing and connected with the fan, stack and burner controls. A suitable stack (not shown) would be connected with the conduit 32. The design of the heater makes it suitable for natural draft operation, but forced or induced draft may be used where desired.

After the burner is placed in operation, the combustion flame is preferably adjusted so as to direct the burning fuel to adjacent the rear wall of the combustion chamber as shown in Fig. 2 of the drawings. Due to the natural draft of the stack the combustion gases will then be deflected upwardly and flow towards the front wall of the combustion chamber where they will pass out of the chamber through the openings 17 and the conduits 18 inthe top wall portions 14-15 of the combustion chamber into the converter plenums 23 and 24. The combustion gases will then flow through the convector plenums and around the members 30 into the header 25 adjacent the rear of the heater where they will be accumlated and pass through the conduit 32 into the stack and to the atmosphere. The heater is provided with suitable automatic controls so that after the combustion chamber and plenum had been raised to a suitable temperature, the blower fan is started to and blows air into the substantially closed combustion chamber casing as shown in Fig. 2 of the drawings. The air from the blower flows upwardly about all surfaces of the combustion chamber and at the sides of the chamber flows through the spaces 70, between the plenums and the top wall of the combustion chamber, into the space 71, between the inner ends of the plenums and outwardly through the nozzles 59. Some of the air passing upwardly along the sides of the combustion chamber will ow through the member 30 into the spaces 71 and other portions of the air flowing upwardly from the sides of the combustion chamber will flow between the top walls of the plenums and the heat shields 63 to the nozzles 59. Likewise at the sides of the combustion chamber the air will flow between the heat shields 63 and the sides of the outer sheathing cooling the sheathing and pass upwardly to the nozzles 59. At the front of the combustion chamber the upwardly flowing air will wipe the front plate of the combustion chamber and flow to the nozzles 59. At the rear of the combustion chamber the upwardly tiowing air passes over the header portion 25 in flowing to the nozzles 59. The spacing between each convector plenum and the top wall of the combustion chamber, as well as the size of all the other air passages hereinbefore recited, can be of such size as to adequately and uniformly cool the adjacent surfaces preventing hot spots. By reason of the use of stainless steel the combustion chamber and plenums can be raised to a high temperature which contributes to the efficiency of the heater. As will be apparent from an examination of the drawings tiere are no abrupt changes of direction of the heating air ilowing over the combustion chamber and convector plenums which would also contribute to hot spots.

The details of construction shown on the drawings are for purposes of illustration and not limitation except as necessitated by the scope of the appended claim.

ln a space heater, a closed combustion chamber having side walls, a top wall connecting said chamber side walls and having opposite faces converging inwardly and upwardly from each side wall, a bottom wall connecting said chamber side walls, and front and rear walls connecting said side, top and bottom walls, said front wall having an extension above said top wall, a substantially rectangular hollow convector plenum disposed above each converging face of the chamber top wall in parallel spaced relation thereto, the opposing adjacent inner side walls of said plenums being spaced from each other to provide an air passageway between them above the connected converging faces of said chamber top wall, a conduit connecting the interior of each plenum with the interior of the combustion chamber through the adjacent chamber top wall and disposed adjacent the charnber front wall, a header connecting the ends of the plenums adjacent the said chamber rear wall, means attaching said chamber front wall extension to the adjacent ends of the plenums, there being openings in opposite side walls of each plenum and a hollow member extending between said openings, said hollow member being secured to the convector plenum side walls forming a passageway through which air passes into said air passageway and about which combustion gases ow in passing from the combustion chamber to the plenum header, a casing enclosing the combustion chamber and the plenums, said casing having side, front and rear walls spaced from corresponding walls of the chamber and plenums directing air to be heated over such latter walls and through the spaces between the plenums and chamber walls and through the passageways of the plenums, a heated air outlet in the casing above said chamber, a combustion gas outlet conduit extending through said casing into the plenum header, means forming a registering inlet opening in the front face of the combustion chamber and casing, a combustion burner nozzle extending through said openings, and means including a fan within the casing disposed below said combustion chamber for forcing air to be heated over said chamber and plenums to said heated air outlet.

References Cited in the le of this patent UNITED STATES PATENTS 1,218,288 McPherson Mar. 6, 1917 1,634,706 Carroll July 5, 1927 1,991,449 Cornelius Feb. 19, 1935 2,109,876 Bard Mar. 1, 1938 2,114,584 Aunger Apr. 19, 1938 2,160,269 Jorolemon May 30, 1939 2,172,667 Nelson Sept. 12, 1939 2,376,140 Henderson et al. May 15, 1945 2,430,393 Elmore Nov. 4, 1947 2,514,011 Ruff July 4, 1950 2,555,842 De Lancey June 5, 1951 `2,612,153 Gibler Sept. 30, 1952

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