US2602441A - Gas-burning wall heater - Google Patents

Description

July 8, 1952 J. H.-Ho|.'|.|NGswoRTH ErAL 2,602,441

GAS-BURNING WALL. HEATER 2 SHEETS-HEM 1 Filed April 23, 1951 F/GZ ' INVENTORJ.'

./oH/v muwssmrff, BY KARL L. 5505,

/1 TT OR/VEY J. H. HOLLINGSWORTH ETAL July 8, 1952 GAS-BURNING WALL. HEATER 2 SHEETS-SHEET 2 Filed April 23, 1951 l-'LUE HEIGHT ABOVE DRAFT HOOD- FT.

/NNER'WALL I TEMPERATURE TA kE/v HERE IN VEN TORS. JOHN H. HOLLINGSWORTH KARL L BEDELL ATTORNEY are disadvantages.

Patented July 8, 1952 4 UNITED STATES' PATENT OFFICE GAS-BURNING WALL HEATER .lohn H. Hollingsworth, Altadena, and Karl L. Bedell, Pasadena, Calif., assignors .toi Holly Manufacturing Company, Pasadena, Calif., a

y corporation of Californiar Appiication April 23, 1951, serial No. 222,500

in areas Where gaseous fuel is cheap. They offer a number of advantages. They are relatively inexpensive to build and simple to install.` If

properly constructed',` say in accordance with the standards of theAmerican Gas Association, they are safe. They are relatively economical in operation and'heat space quickly-an advantage in climates where the mornings or nights are cool but the days are relatively warm. But there Conventional wall heaters tend to produce high wall temperatures Vabove 'the heater and adjacent the flue, and thisis so even when 4the installation meets the requirements of the Underwriters LaboratoriesA and presents no re hazard. High wall temperatures,

even in the absence'qof nre hazard inthe wall,

vevidence a heat loss in the'flue." Even when this `loss is notY excessive, the customer reaction is lpoor. temperature-by bleeding air into the flue, the

If an= effort is made to lower the wall resulting heat loss, ythough apparently lower, may

.actually be increased.

heated circulates. A tall hollow radiator/is set inthe box and is red inside with rgaseous fuel. Air rising Vthrough the box is heated by the radiator :and'passes out into the room. ,Heat not transferred by the" radiator' remains in the 'gaseous= products of combustionv and/,is wasted up the flue .connectedtothejt'opy o f the radiator'.

A draft hood or diverter maybe 'connected in the fluejabove the radiator. Thisl hasr a relief outlet, usually* into the room through thejbox in which the radiator is disposed, and serves-several purposes'a -If'the flue should becomechoked, the flame in the radiator will not be blownout andthe" gaseous combustion products will escape through the relief outlet. If- 'a down draft 'should develop in theflue, the same results will follow. On the' contrary, if an. excessive up-draft should exist due to an excessively; high ,chimney lorv flue, or should develop temporarily due to a hghWinLd,

vso

'increased lossof heatup the flue.

2 air from the room will be sucked into the flue from the relief outlet and the relief outlet-will thus prevent the excessive draft from interfering with proper combustion in the radiator.

For'safetys sake, a wall heater of the type described is so designed that, even with-onlylthe four foot flue employed in American Gas Association tests, a considerable volume of warm air will pass continuously into the flue through the relief outlet froml the room. WithV the taller flues customarily used veven in one story houses, thisvolume is increased. A two story iiue still further increases the draft and the amount of warmair lost up` the chimney or flue." The warm airsucked intothe ue through the draft diverter thus represents ar constant andsubs'tantial heatv loss, which increases as draft is increased.A

As indicated at the outset,rthe flue-above vthe radiator tends lto heat the wall in which4v it is enclosed. The more the fuel burned, the hotter the-flue' gasV-thehotter the wall and the greater In cold'weather,

ously. hot due tothe large amount of fuelv burned, and this hot wall condition is accompanied.' by If van attempt is made tot reduce the wall temperature by bleedinggin air. from the draft diverter, a. lower wall temperature is obtained'but only at the expense of a still further decrease in heating eiciency.

As avresult"` of our investigations we have de'- velopeda wall heater which t" (a)` eliminates high wall temperature; .l

(b) does so without decreasing heating efficiency and in fact with a substantial increase in heating efficiency;

' .(c) increases air circulation in the room in which-the heater is installed; and

(d) v can be installed with flues which normally would produce excessive draft, without deleterious effectupon heating'efficiency, so'that the `heater is adaptable tofa greater variety of draft conditions than conventional'heaters While keeping heating efliciency high. v n 9' y In accordance with our invention, a Wallheater is Vconstructed in two sections. The lowerA section' comprises a Vgas-firedy hollow; radiator disposed in a box in the wall yof a room immediately abovelfloor level; The vupper section is likewise n af'rfadiatorfjdisposed .in a box in the, wall "and placed above fthe" kfirst radiator but mainly below the: ceiling. Ther two radiators' are connected kin series. Gas` is burned in airin the first radiator and the resultingfflue. gases rise v.through th extending walls of the box. Box'andgenclosed radiatorare thus installed together inthe-wall, .preferably with an insulating space in thezA wall outside the box.

of equal height outside.

V,flue 1 temperature.

3 second radiator and are discharged into a flue connected to its top.

No damper or the like for ccnstricting the flow of the flue gas through the two radiators is provided, and a draft diverter is connected 5' between the two radiators, instead of at the ue, as is customary. This diverten has its yreliei` opening into-the room, preferably through the box in which the lower radiator is placed.

Air to be heated is admitted into the lower portion of the box from the roorn, r ises along the lower radiator and is discharged intothe room at the top of the box. Airi from floonlevel in the room is passed upward through a= separate conduit into the bottom oftheupperfbox in which the second radiator is disposed. Preferably this separate conduit is disposed aroundthe sides or back or both of the lower box. Air introduced by the conduit into the upper box riseslalong the second radiator and is discharged into the room through an outlet-inthe upper boxnear the Ceilingf The secondi radiator preferably is formed .-asy a unit With its .bQX,..a.r1d spacedfrom theupwardiv signed so that anormal draft with avery short flue will barely cause air tc be. drawn intor the Asystem through -the draft-.hood and so thatincrease in chimney eect does not increase dilu- '35 tion through the draft hood ,to va substantial degree.

The 'reasons for the structure just described and the results thereof are as follows:

Draft is Whattends to. make gas :move upward 40 through a flue and is the `result.;of a pressure dierentiaL i. e. the difference in. the density. of

the column of gasin'the flue andi a likecolumn Hence i .theoretically available draft is a function offlueheight and Although ithe; theoretically available .draft is a measure `ofgstatic condition and ispnever fully obtained dueto frictionallosses in.v the fluep the actual draft.l at any flue ytemperatureis still jcloselyrelated to the-.flue height andY any increase inthatiheight; willcausethe flow of gas to increase .until thetotalenergy.loss of the systemedualsithe theoretically.;available draft. :The function o'f the Idraitf.hoodiorrdiverter;in the device of the invention is..,torstabilizeiidraft .conditions existing4 within the lower radiator vregardless of variations in draft :conditions .above it. This is aocomnlished. vicy-nlacingsuitable .bafiiesinthe. .draft hood (soesto. direct.. the.f10w of...gas properly)- and .by the vent which, provides a. Sollre .0f lfelef' .air- The; qlafhhoodfes, :E913 Qontrol ,the draft action .established Within ,the flue but only its effect on .the combustionzone in the lower radiator. j n 'v Draftin a flue may be `controlled satisfat'forly and safely in Vmany instances by. a damper." They have been usedffor' many .years `.inthe Aiiue's of fireplaces. `VAdjustable dempers, however', are. not satisfactory the fluefof fa gas-bliifliidef, because of the'possibility'offaspfhyxatio Re ognized testing agencies and'gOl/.Brlm'eil'b'ds condemn them, and Athey jarej forbidden'jin Vmany places V by building codes andordinances.

tends toward a constant value.

in dilution throughthe draft hood.

tially proportional to the velocity of such flow. But under conditions of turbulent ow resistance to ow is more nearly proportional to the square .of the velocity. Consequently, if the horizontal cross section of the upper radiator is constricted. preferably until turbulent flow conditions obtain, alarge increase in draftfsayduefto a tall chimney or a high wind, Willnhave a minimum effect at the draft hood below the radiator. Hence the suction at the relief opening of the draft diverter If the system is designed so that it barely draws in air through lportioniif-theflue height is increased. Loss of even if the wall heater is installed with a flue system that creates excessive draft, and heating efficiency is thereby improved.

In other --words,;the cross section offthepsecond radiator is chosen sogthatias a ,conduit it v.willfiust Ahandle the maximum products of combustion @to Vbe conducted inA theyirstradiator,Y with scarcely any dilution throughthe draft hood. -Withzsuch y a design, a markedfincreasein draft will produce a minimum increase; in draftx atthe` .base .-.ofethe second radiator, and hence @minimums-increase ByV .drawing the L4cold- .air zup. around the. .sides or the back, or both, ofthe lower box, ,the-,neighkboring-wall surfaces are cooled and morefuel may ibe'burned safely without attaining excessiye /lowerwallitemperatures. HenceL the-heating :ca-

pacity lof the apparatusis increased. Moreover, the air for the upper-'heat exchange..becauseieit is drawn from a low #level has alower temperature. so that the h ea'mtransfer` from ,thejupper radiator. is increased. In this vway.;.the4 amount of heat; imparted tojthe air lpassed .through :the upper lbox (i. e. the conduit Varound the yupper lradiator) is increased, with a Aresulting :improve- -rnent Ain over-all heatingefhciency. Thirdx the use of` cold. or low level.; air -asfeed to the secondary heat exchanger 'makes it; possible safely tov v,en-

case this secondary-heat.exchanger .vin, a;- com .-bustible ywall. Fourth; the structurezof the 4 ,i-nventionfis such thatvv the hotterair isfbroughtout intothe room at an intermediate level whileioooler but. still-warm air. is introduced int0;'jthe1. upp1` part of the room near theceiling, thus reducing stratification Yand. increasing air circulation.. in

vThe over-all-effect Y of they application-ofithe invention-is striking. AAIn actual -tests fit-raised thermalefficiency by -more-than 10% f increased the-volume of warm: air circulated inthe-room by vapproximately 25%V and-reduced Vupperevvall temperature from about 150 'F.'above'room-temperatureto about F. above room temperature. At the sameA time, thecost ofthe secondary heat exchanger employedwas .but little .moreLthanltliat of the I iuesection whichlitreplaced.

The foregoing and other aspects. ofour-invention .will .be understood Imore, thoroughly `nfthe Hennef-.the fouowingffidetaileddeseriptmntaken irriconiunction with. fthe..aceompanyingfdrawing ini-Which! Y y :Fia 151s; a. diagrammatcgsectidnalr.,elevationfof a .presently preferred embodiment;ofi-theifwall heater ofour invention; i..

Vrlligs.l 2; Brand.; 4. iarencross :sectionsitaken reispectivelymalong ,'.theli-nese Sis-3,: and 0f;ifFig,.1';f e r 1 311i;

`Fig. 6 .is a graph of the results of tests con ducted to determine the relative heating efliciency of conventional wall' heaters and that of the invention for various chimney or flue heights, thermal input beingthe same in all cases; and

Fig. 7. is a, plot of wall temperatures against flue-temperatures obtained in testing wall heaters ofthe invention, as compared with similar plots for conventional 'heaters equipped inv one case with an accepted composition flue (Portland cement-asbestos) and in the other with a standard double wall metal flue.

Figs. land show a wall heater set in a wall Il of a room and having two separate chambers I3, |4, one disposedabove and oiset centrally of the other.v y

The lowervcharmber I3 isa tall shallow box or jacket, setuprightfin a recess of the wall. The box is rectangular in section both horizontally and vertically. Y A hollow radiator or heat exchanger I5 preferably made of a black surfaced metal and ofv considerably smaller horizontal cross sectionthan .the jacket, is disposed centrally of Athe jacket in an upright position. rIfhereis an inner annular air space ll between the jacket and radiator, and a second vouter annular air space I8- between the jacket and an encompassing` heat vconductive shell I9.v The shell is box shaped and ofgreater cross sectional dimensions thanl the Vjacket which is disposed centrally within it` The shell has a front side 2l exposed to the `room and an opposite rear side 22 spaced from-the back wall 23 of the recess, leaving an air space Ior conduit 24 behind it.

.Neither the jacket nor radiator extends to the b ottom of the shellas shown in Fig. 1. However, the jacket could extend -to the bottom if itwere provided with a series of ports for circulation of ainy v e Y A gas burner 21 at the bottom of the shell is so placed that it projects Aflaming gases into( y theopen bottom ofthe radiator.

.The front of the shellis provided with two spaced sets of louvers 29, 30, V1r't'elatively 'cold air is drawn into the chamber through the lower louvers, near the 'floonand discharged asrheated air to the room through the upper set of louvers, adjacent the top of the shell and about midway up the wall. The air may rise through either the annular space Il dei-med by the heat exchanger and jacket or between the jacket and the shell in the space IB or between'the shell and the wall in the space 2li, with the combustion gases ascending through the interior of the hollow heat exchanger. The lower jacket `or chamber does not extend to the top ofthe shell and `hence hot air rising-inthe jacket may escape into the Vshell, and thence to the room through7 the upper set of louvers. The outer vannular air-'space-Zl-serves primarily as an'i'nsulating chamber, protecting the rear wall of the recess and the sides of the shell from excessive heat. The gas burner is provided with a Ythe middleklouver; K

Cold air, say at about 70 F., passes up from constructed of a dark surfaced heat radiating metal. VSave forthe lower .end which extends f intov the recess. the second heat exchanger is completely enclosed in the upper wall in an up.- right position.

. The second box or jacket Ill is completely en closed in the upper wall yand is centrally-disposed around the second radiator to which. it is attached. The second jacket extends from the top of the recess to the ceiling of the room, forming two annular air spaces, a rst air spaceY dl (see Figs. 1 and 2) between the jacketv and the radiator and a second air space 42 between the jacket and the interior surfaces of the Wall'. The air space 24 defined by the outer wallof the shell andthe inner surface of the back Wall of the recess opens into the air space 4I .between the upper jacket and second radiator.

Air heated by the upper radiator and rising through the air space dl is discharged .into the.'

room through a. lateral duct 44 connecting-the jacket to the louvers `cfa register d5 set flush in the wall near the ceiling of the room;` The outer air space d2 between the jacket `and the interior surfaces ofthe wall aids in. preventing excessive heating ofthe wall. f

As shown plainly in Fig. 2, 4the* chamber and the radiator .of the secondary heat exchanger are of flattened cross section, both being considerably'shorter transverse to the Wall than parallel to the wall., Conveniently, both radiator and shell yor jacket rare made of opposed sheet steel halves welded together along lapped flanges. The flattened section of the exchanger is useful in that it permits large heatexchange capacity to be installed in a relatively thin` wall. The radiator is substantially smaller in cross section .than the lower or primary radiator.

The operation of the. apparatus described in conjunctionwith the drawings is as follows:

Gas is burned in the lower radiator. This gas may attain a temperature adjacent the burner.

as high as 2000" F. The hot gases of combuse tion rise through fthe radiator and the draft hood into the second radiator and thence are exhausted to atmosphere. Thejhot'gases in rise ing through the lower radiator decrease in tem`n peratureto about 650 F. This temperature is.

reduced slightly in the drafthood.. The'. temperature of the gases vleavingthe upper end of the sec. ond radiator is. about 450 F. Air enters the space' in the lower heatexchanger around the radiator at oor level and'at a temperature of aboutsayl l 70? F. `In passing up through the jackets in. the lower exchanger the temperature of this air is increased to about' 375 F., at which tem-v perature it is discharged into the room through the iloor level to the box surrounding lthe second radiator through the wall and in passing to the upperlouver (of "the second 'heat exchanger) adjacent the ceiling attains a temperature of F., at which temperature it is discharged.

Extensive tests have been made to determine quantitatively the effect of the heater of the invention on heating efliciencyand wall temperature. These results are summarized in Figs. 6 and '7 and there compared with heating efciency and wall temperatures observed with f conventional wall heaters of high quality under like conditions.

Fig. 6 illustrates the effect of draft (chimney action) upon heating eliciency with conventional Wall heaters and those `of the invention. The

iueheight:forv heater-zA, flwhich.'y represents thai average.; values obtained .in actual. tests :with: La#

number of. makesof heaters disposedL inaA wall,...

with a suitable draft hood at thettor'v.A of :the 1.

heaterrand". about half-.way up the wall: in .each

casefatwhich point. it .was connected -to a stands...- lard flue. section; .the :height aof.A which.' iwasii'- i .'-L'i creasedas shownzin order-tofincrease thedraftz: stepwise, The linermarked: HeatenB isv a. plot-l ofa'ctuall eiiicencies .obtainedfwith the heater;

illustrated; inl; Figs.. 1. toY .5, as fwith. .the .convenz-p tionaluflue section.` immediately. .alcove the: draftv i hood offiheater. A replaced .bya secondaryheatV exchanger.. The radiatorl of this secondgtexff. changer was' of uniform''.lout"small.horizontalA cross' section so'V thatwiththe. shortestflue height,.

the draft hooctmbarely..drewv air. '.LBotlnheaters.

A..S.and B'. burned iuel'r. equivalenti to';255,000 B...'t.. u./.hr..

Figz shows invention.. is superior to. the. conventional i gas= fired wall-'heaters irrespective.` of iiueheightzandr. that asfue height anddraft are vincreased'.the'- superiority of. ourv heater becomesnmorexmarked'. Stated in another way, the. heater: of .the invent-v tion.. has: a high. thermal leiciency which decreases on'ly slightly' asY draft: increases; whereas theconventionaliheater has a; lower .eiciency tof.`

comes sharply Worsesas. flue height is increased.,` Fig.' 7 illustrates the decrease'in wa'l'lltempera; x

start'wth. and" this initial .lower efficiency. he.;

ture; -in the: neighborhood. ofiA a "wall .heater brought about. by the invention; In .the figure,v nue temperature isplotted againstupper'vwalli. temperature'. for- (1). a conventionaliwallheater` extending about'halfway up'the wal'lricf; a room;

with a drafthoodn at th'etop.. and aA standard:

composition flue of cement and asbestos. in the wall above'it; (2) the; same conventional heater' withv the" same :draft'hood: but.. employing. ia standardidou-ble .wallfmetalueL in' the; Wall; and. (3).l the heaterof the. invention; similar tothe;

other .two .heaters 'except that .ther-flue sections'.

were replaced'by a secondaryheat .exchanger `in thewallifedwith. air fromioor level and. dis-:

charging at ceilingrleveL. asV illustrated. in

Figs

1i toff5.

Irrespectiveof flue temperature,- wall tempera tures with the. apparatus of: theinvention are.'

consistently. lower than .those obtaining when conventional heaterswith-either of the usual: nue i typesare'used. This. means thatfin 'times' of verycold i .weatherywh'enn the demand is high, VtheV heaterofztheuinvention maybev called upon to" burn'. a great fuel *load* safely; something. that cannot Lbe said of theotherfheaterss- Itfalsof. means that under normal conditions, no annoy.;v

ingf-ffhot wall'. conditions are'obtained.

Wesclaimi` 1. In a. wall. heater -forI burning gas; thecomf bination which'. comprises aV first box@ adaptedfto plainly.. that. the.. heater. .of the.

belmountedn.aiwallofl'a; roomfto extendl'upward therein from a level near the floor of the .roomv to: va= level -part way-to fthe ceiling; a first l'hollow radiator mounted in. the-'box and: spaced -fromtne-L- walls-thereof, meanslfo'r burning .fuel in thesrstis radiator; .means .connected-to 'the/lower' portion.l of the firstfbox `for'.introducing air thereintof near the -iloorv4 of the room, means?. connected.' to

thefupper portion Iof fthe rst box. for.' discharge ing-.air intothe'roomfrom the `box-near itstopgz asecond' box'. adapted tombe-'mountedrrin the wall.. above the:y rst' box` to: extend ffroma level-"justfv above4 the 'first hoxfto a level' near'fthe'xceilling...a.

second hollow radiator disposed-fin the 's'econdib'oxr` and spaced'from vthe-walls thereof, the horizontal cross section c'ffthe second-radiator? being sub*-` stantially' "smaller-'thanthat' of the .rstlrradiator,` 'l means connected with the upper portion-f otr-the.-Z

secondA box' forA discharging tairV from the' vsecond radiator'.

2. Apparatusaccording Ato claim l providedwithv a. baiiie`-"disposedv intheA first' box"kzfehindfthe*- rst radiator and spacedfrom"thefradiator and'.

alsor Vfrom the rearA wall* offthe' box. Y

3. Apparatus'accordingrv to clai'mfl providedwitha baiiie'disposed'in the-"rst'lbox" behindthev rst radiator and spacedl from 'the radiator and?r also" from the 'rear' wall' ofithefbox to provide fa conduit between :the rear wall" of thel box 'andthe hailie,v said conduit being openeat VtheloottomL andv also at" the topandin communication-'atlthectopiJ with` the'interior 'of lthe rst box". f

. 4. Apparatus according to claim 1 in whichfthey secondn radiator is composed y of a Ashallow-2front member and va shallow-"rear member.VA

5. Apparatus according toclaim l" in which-the? secondv box is composed offa shallow frontv member anda shallow rear'member.=-

Joint 'rrPHQmNGsM/fonmrf KARLLBEDELB. Y

REFERENCES; CIT ED 'Iheffollowingf` references are of .record inthe.. `ilefof this .ipa-tent:`

UNITED;` STATES.' PATENTS' Number: Name Date.:

1,361,389r i McLeod. .Dec. .7, 1920: 1,698,775 Traut'.- *Jan. l5-,-.1929.

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