CA1059397A - Fireplace chimney furnace - Google Patents

Abstract

FIREPLACE CHIMNEY FURNACE

ABSTRACT OF THE DISCLOSURE

A heat exchanging chimney in the form of a tubular heat exchanger which functions as a furnace and which is mounted above a conventional fireplace with a preferably transparent or trans-lucent closure means over the front is described. The fireplace is constructed such that it draws outside air for combustion of the fuel and air from the rooms being heated. The chimney is specifically in the form at least one vertically oriented multiple tube shell type heat exchanger in place of the convention-al fireplace chimney wherein the flue gasses pass inside the tubes and the room air is heated inside the shell. In operation, the fireplace and heat exchanging chimney achieve substantial economies in utilization of fuel, particularly wood, over fireplace with conventional chimneys.

Description

~- loss 15 SUMMARY OF INVENTION ~ ~ ~ ~~~~~~~~ ~-~- ------------------ - - -The present inve~tion generally relates to an lmprovod apparatus for the reocvery of the heat ~rom firep:Lace flue gaseo `
by mean~.of a vertically oriented tubular shell type h~at exchange mounted above the fireplace. In partlcular, the present ~nventlon 20 relateY to a flreplace which utllize~ outside air ~or combustion of thG ~uel rather than air from the rooms being heated. .
PRIOR i~RT
The pr$or art i8 illustrated by U. S. Patent Nos. 172,65 1 916,559~ 1,681,995~ 1,727,228; 2,430,393 2,622,587~ 2,789,554J
25 2,791,213t and 3,834,619. These patents gencrally ~how flreplaces where some heat exchange 1~ achieved ~etweon the glue gases ~rom the fireplace and room heatlnq alr in thc fircplace shell. :~n many of the~e unlt~, the alr for the combu~tlon of the fuel i~
provlded through an open ~ront of the flr~place. ~hl~ constructlo ' .

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produces a ma~or ~ource of heat 1098 from the hulldlng even whe~ .
the fireplace i~ not ln u~e and i~ lneff~clent sincP hested rooc alr passes up the chlmney nfter belng utlllzed at leas~ parti~lly for co~bustion of the fuel. Such a system 18 basically lllu~trated in ~ennett Patent No. 1~2,656 ~1876) and Jones Patent No. 916,559 ~19O9) and ha~ been suggested ~ore recently by Glover in Patent ~o. - :
3,834,619 tl974).
U. S. Patent No. 2,622,587 to Dupler shows ~ complex form of f~replace device wherein out~ide air is brought into th~
fire chamber. In this device, an attempt wa~ made to make th~
heat exchanger as small ~nd compact a~i po~sible within the gener~l con~ines of the fir~place housing, probably to provide a un~t wh~ch can be a ~ubstitute for the conv~ntional fireplace. A~ a result, the flow of thq flue gases i~ restrioted by the sharp bend~ in the tubes forming the heat exchanger.
OBJECTS
It 1~ th~re~ore an ob~ect of the present invention to provide a fireplace chimney furnace which does not use air from ins~de the rooms of the building for combustlon of tho fuel. Furthar it is an ob~ect of the pre~ent invention to provlde such a furnace which achieves maximum heat tran~fer from the flue gases w~thout impeding the ~low of flue gases as they are expelled fro~ the fireplace. Further still, lt ls an object of the pre3en~ in~ention to provide 3uch a furnace which is simplu and economical to construct by Gomparison to a co~-vcntional fireplace chimney made of brick and which is more .
efficlent in terms of fuel economy thsn a conventional flreplace. ~
These and other ob~ects will become apparent to those skilled ln ~-the art by reference to the following aescription and by reference to the drawing~.

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IN THE DR~WINGS `:
~ 33 _=_a Flgure l i~ A front cDoss-~ectlonal vlew of a bullalng~
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. particularly lllustrating in a front cross-sectio~al view the ,_ ~ _ .. ~ . .. ,._ . ~, j , _=. ~, ~, preferred flreplace chimney furnace oP the pre~en~ lnvention .-. . . . . .. . _ .. __ ~ c : ~
wlth a lower primary and an upper secondary shell type exchan~er .
ln positlon. :
Flgure 2 16 a partial slde cro~s-aectlonai v-ew o~ tho fireplace shown ln Figure l.
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. ~igure 3 i8 a plan cross-sectional v~ew alonglinQ 3-3t . = ~
Figure 4 is a plan cross-sectional view along line 4-q: Figure S :
18 a plan cross-~ectional view along llne 5-5 and Flgure 6 18 a . . . - . ~
plan cross-sectlonal view along line 6-6 of Figure 1, particularly illustrating various sections of the primary and secondary ~hell~
type heat exchangers of the fireplace chimney of the present ~n-ventlon.
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Flgure 7 i~ a ~chematic di~gram o~ ths fireplace chimney Purnace of Flgures 1 to 6, particular~y illustra.ting the flow of flue gases as ~7ell as the flow of the co~bustion and heating alr..
~lgure B ls a schematic front cross-sectional view of a building illustratlng a variatlon of the flreplace chimney wh~oh uses a primary heat exchanger and a plenum for the heated air with a conventional blower system. : .
G13NE~ DESCRIPT~ON
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The present invention relates to ~n improvement ln ~
hullding wlth a fireplace having a combustion chamber, ~ front openlng leadlng into a room ~nd means Por closing the opening .
and havlng a flue gas exit from the fireplace, as a replaoement t for a conventional fireplace chimney which comprisess multiple heat ex~hanglng tubes mountea above the flue gas exlt of the fireplace ~uch tha~ the flue ga~es vent up~ard through vertlcally I I -~ I

15939'7 1 ~¦ oriented openings in the tub~s, where~n the tubes extend su~-sta_t~aIl`v`~ë~een at least a floor and a celling o~ a room of the bulldlng~~~'~housing 3urrounding,~ ~upporti-ng and enclos~ng~'~
the-~ub~ce~t--:for=~the openlngs wlth at l~a~t one conault ~or cold a~r-lnIet lnto the housing and at least one conduit for hot air exlt-~om ~e ~ouQing into at least one room of the building~
a chimney-~:n--Qealed gaseous connection with the opening~ ln the tubes and lead$n7 outside the-building which proviaes aD exit ~or the flue-gases-from the tubes of the heat exchanger; and an air conduit leadin~ from outside of the building to the bottom of tha co~bustion cha~ber. By u~ing the multiple tube heat exchanger in place of a conventional chimney for the fireplace, large amounts of heat-which would be wasted by a conventional chimney can ~e economically-recovered. Because the openings in the tube~
are vertlcally oriented, the venting of the flue gases i8 .
unrestricted. '' The vertically oriented tubes can be either straight, which i8 preferred, or they can have sllght bends which do not significantly impede the flou of the flue gases. The tubes can~~
- 20 have fins on-the-outside and the like for better heat transfer to heat the heating air. Preferably the tubes are made of ~et~i such a9 steël-plpe.'~ - - ~ ~~' ~ '' ' In gene~ral the fireplacé chimney is constructed in a manner which u$'e:s safe construction practice. Thls practice i~
well known to those skilled in the art. It i9 preferred that the air inlet and exchanger except for the fireplace be enclosed in a separate ro~m;~ -'" ' `' ' ~ Particularly~preferred'is the use of a secondary tubular heat~excha~-ger~m-ounted above the first heat exchanger such tha~
the flue gases pass inside the tube~, wherein the second tubes are enclosed~'by a houslng, whereln a second outside air conduit ^ I 1059397 li~ provided $n the secona housing such that air can pas3 aroun~
¦the seaond tube~ and wherein a second conduit 1B provl~ed lead~ng ¦rom the ~econd housing to the bottom o~ tbe combu~tion cbamber.
¦The preferred con~truction Initially allows the heating o~ inlet S ¦fireplace air by the ~econdary exchange~, since a$r flows to tho ¦combust$on chamber. As the 3y~tem approaches a ~table tempera-¦ture, the air flow automatlcally reverses and exce~ air i~ taken ¦from the bottom of the combustion ch~mber to keep the fire ~amped ¦and burning under control. In the most pre~erred ~orm, the direct ¦air inlet to the fireplace is coupled by a plenum to the air inlet Ito the secondary exchanger so that preheated a~r is ~upplied to ¦the combust$on chamber regardles~ d the dlrection of air flow i~
¦the secondary exchangær. - ' -- -ISPECIFIC DESCRIPTION
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¦ Referring to Pigure~ 1 and 2, the preferred embodiment o ¦the present invention 1~ illustrated in the ~ettlng o~ a build~ng ¦lO having a conventional basement ~loor 11 ~upportlng a hearth ll~a) of brlck or the like, a ~ixst floor 12, a ceiling 13 and ¦pitched roof 14. A~ can be seen from Flgure 1, the preferred ¦ fireplace chimney furnace of the present invention extends ~rom ¦ above a conventional fireplace 15 to above the roof 14 in ~
¦ generally vertical or$entation. The f$raplace 15 can be of $he preformed type and made of concrete or can ~e made from hrioks.
I ~he fireplace 15 i8 placed on the ba~ement floor 11 and ¦ has a conventiona~ ~ire chamber 16 with an upwardly extendlng flue g~s exhaust port 17. A conventional front opening 18 i~ .
provided in the fireplace 15 which i9 closed by gla~s covered ~-access door~ 19 or other closure means which ¢an radiate heat-into ~ room in front of the fireplace. The front or face o~ the fireplace 15 can be provided with ~ecorative brick 20 a~ shown ~ -in Pigure 2. ~
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! l)s939~l . -~ hs tubul~r.,,exchanger u~lt ~l of the present lnvention prefera~l~.imo.unt~ ireGtly on the axhaust port 17 o~ the flreplac . ~,~
15. --~hQ uni~ ~1. i8 ~con~tructed BUCh that flue gase~ rlse vertical~ Y
~rom the p~t 17-.into~_a-plenum or chamber 22 formed of sheot metal:haY~nq ~ ~Op 2:3r V~rtlcally orientea tubes 24 havinq . .
openings 2~ ex~end above the plenum 22 through whlch flue gase~ ~:
. can-pa~s.- ~he construGtlon o the plenum 22 can best b~ seen by reference to-the cro~s-sectlon in Flgure 3. Surroundlng the tube~ .
24 19 a houslng 26 wh~ah 1~ preferably made of galvanlzed sheet .
steel. As shown ~n Flgure l, the ~ube~ 24 extend above and below the first floor 12~ however, it w.~ll be appreciated-that the tube~ :
. 24 could extend between any nu~ber of floors. A cross-sectlon ~:
of the heat exchanger-unlt 21 i9 ~hown ln F~gure 4, where~n the hou~ing 26 18 sho~n--as supported by vertlaally positloned angle . :.
lS irons 27 secured to the insiae o the houslng 26 by metal screws 2 .
Conventional ~urnace ~ealing (not shown) such as asbestos or fur^ ., nace cement,can be u~ed between the ~irepl~ce 15 and exchanger 21.
. .... ............At the ~ppermost part of the housing 26 19 provided an e d or clo~ure plate 3~ which supports ends of tubes 24 around the.
20 openings 25, a~.shown-ln Figures 1 and S. Integrally formed with the.plate 30 i9 a,f,langs 31 extending perpendicularly to the' .
central,longitudinal axls of the tubes 24. The flange 31 is provided with bolt holes 32 and i8 constructed such that it flts .
in mating relationshlp wlth a simllarly constructed ~lange 41 a~
~et forth hereina~ter. The housing ?6 and plates 23 and 30 seal the tube~ 24 such that a chamber 33 18 providcd surroun~lng the tubes 24. .., ~ , ;,,..., . , -.-At the floors of rooms 1 and 2 are provided condults. 34 le~dlng into the chamber,33. ~he chamber 33 is also provided with 30 a secona condult 35 leadlng into an upstalr~ ~oo~ 2 above the ~
fireplace 15. The condult 35 directs the heat~d air leaving tbe ,,.
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ou3ing 26 llpward'~and~into'`~lie`''roonis~pref~rabiy u~ ~n angle bet~teen abou~ 30~and 45- from~~he''hori'zontaI~ pIarie. q~he condults 34 as~l5 35 are'~ùppor~ed'~by~'two''waIIs'36 aiid`'3i extending batween the ' _ . . . .. .. .. . . .
floor~''Il and'l2 ana ~he ce~IIrig'I3 ln the room~ 1 ~nd 2.
S -- ~ Through one~~lde=ana~undersIae of'the fireplace 15, l~
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rovidëd~a conduit 3~'whIch'''extenas'through th~ roof 14 to provlde out~ide`air to the bottom~oi the fire `chàmber 16. The condult' 38 ~ prov~ded with a butterfly valve 39 which functlons as an air damp~r.`'' Préferably~'a thermostat 40 r~ulates the valve 39 lO to au~omatically maintain the ae~ired temperature in room 2. ' 'Mated to the flange 3i i~'a second flange 41. ~he flaT~ge 31 and 4I are~~ecured together by bolt~ 42 and conventional seal-ing agents such as asbestos tape and'furnace cement can be use~l' to insûre a seal. Attached to the flange' il' 1~ a box-like rec~-, ,, "
15 tangularly cross-sectloned bous1ng 43'which is also sho~n in Figure 6;- Ad~acènt'~he flange 41'1~ a plenum 44 with a top ` ', late 45 secured to the side~ o~ the hous1ng'43. A palr of clr- ' ,';
ular flangeQ 46 are mounted on the top plate 45 which mount ','' ' ertically~orie*~ed steei 'chimney~'plpes 47' having openin~s 48 ', , or the exit of'thë fIue' gases and have a cro~s-seotloned area ':
qual to''or greater ~han"~thè 8U~il of the areas of the' openingY , ,;
5 of'the multipie t~ibe~ 24. ~rh~pipes 4? are 6upported at the`~r , - -uppermD~t ends by a plate 49 which is fitted to and encloses the ' ousing 43. As shown ln Figure l, the plpes 47 and air inlet ondu~t 3B are surrounded by a decor~tive' chimney 57 with a . , . ~ :
ectangular-cross-~ectiori arid with a louvered opening 51 on the ' iaè~~or'air entry as shown by the arrows. The chimney 5~ should e adequately ~pacèd~from the hou~ing i3 if lt i~ made o~ wood as hown in Figure l. Brick ~not ~hown) can be placed ad~acent the . -?-~ i ¦ . .
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housing 43. A con~rete or 3teei;~over-50 is~mounte~ on the'piato` . ,~, 49 and around the plpes 47 and--èxtends-~à~erally to`ehe~~op of~~
the decorative chl~ney S~. The pipe~ 47 prèferably pro~ect~about 2 inches above the cover 50. --Suitable^roo~ fiashln~~53 i5 pro-vided around the base of the decorat~ve chimn~y~SO as~la' conventlor ~
prac~ice. -~ , ~' At the top of the hous~ng 43 an-a~ad~acent th`e air''i'nlet . opening 51 is provided an opening-52. At the bottom o~ the''' , .:
houslng 43 i8 provided a conduit-53 with~ari~opening 54 leading :, to the bottom of the flre chamber 16. As can be seen from,Figuso 1, housing 43 and pipes 47 form a-ohamber-55 which act~ a8 a heat exchanger 56. . ~~~ ~' '~' ~ '~ ~' Preferably the un~ts 21 and 56 are prea8semb1èd a3d' installed in a home w~th a boom crane which first lowers'tbë, .
unit 21 onto the Pireplace and then the unit 56 on the uni~ 21.
The contraator can ~hen connect conventional heating ducting to the unlt such as that u~ed with a conventlona~~forced-hot~air~~' furnace with which the chimney ~urnace o~ t~e'present inve'n'tion 19 compatible. . . ' ~ ~ ~ -The operation oP the heat exchanger units~21~and~`5~ are best de~cribed by reference to the sch`ematic" diagram o'f'~igur~ ?.
The exchanger units 21 and 56 function separately and the unit'S6 while preferred, i8 not necessary to-the operation o~ the unit 21.
In ~pera~ion of the unit ~iown in Figure3 l to 7, a fire ~9 lit inthe ire ahamber 16 of the ~ireplace 15 by introducing ,,, a solid fuel (coal or preferably wood) or-by'ignit'ing a'gas o~
liquid fuel heater (not shown). Air i8 supplied to t~e chambe~ ~
16 through opening Sl to conduit 38 wlth the valve 39 completeli .~
open. The flue gases pass through the opening~ 25 in the tubes ' :
24 and through the openings 48 ln the tubes 47 and are vente2 outside the buildlng 10. The tubes 24 are in a heat exchange -8- ,:' . .

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0593~7 ~clationship with ~ir ln cha~ber 33 in th~ hou~lnq 26. ~he alr ~in chamber 33 i8 clrcula~od Acro89 the out~lde ~f tbe tubes 2~ by ¦inlet through condu~t~ 34 and outlet through conduit 35 to th~
~oom(s) either by natural convectlon whersln hot a.lr rl~e2 ~aturally and preferably by uslng a blower S9 in ths conduit 3q.
thermostat 60 electr~cally actuates the blower 59 at a pre- .
selected temperature ln the cham~er 33 ln the hous.Lng 26. ~atural . ¦convection w~th hot air rLs~ng continuously circul~tes air through .
: ¦the excha~ger 21~ As can be s~en the exchanger 21 provid¢s an .
¦economic means of capturing substantlal amount~ of heat from the ¦flue gase~ which ~Oula be lo~t by a conventional chlmney. Th~ : ..
¦valve 39 ls rotated by a motor ~not shown) controlled by the ;
¦thermostat 40 ~hioh regulates the amount of alr to the flre ..
I chamber 16 and as the ~ire reaches a stable condition the amount . ;
1 o~ alr needed i8 3maller.. .'.~ . ..
¦ ~ It i3 pr~erred to u~ the second exchanger 56 since it . ::;
¦ provi~en an additlon~l means o~ removing heat ~rom the flue ~ase3 ¦ and secondly provl~es a means o~ regulating a ~olid ~uel fire at .
I various ~tage~ during its development Wh~n the fire i8 beglnning, :
¦ air enters the opening 52 and passes across the outsido of the. :.: ...
l pipes 47 ln chamber 55. ., The air then i9 conveyed to th~ 4ire . . .:
- ¦ chamber 16 by mean3 o~ condult 53, thus aldlng the ignition of : ;
¦ solid ~uel becaus~ o~ the preheated air. A~ the temperature of .
¦ the 1ue gaseq in the ~ire chamber 16, tube~ 24 and pipes 47 . . .
¦ increasos, th~ flow of air in the cxchanger 56 reverses due to natural convoctlon and air from the bottom of the ~irc ch~mber.16. .
pas3es through the conduit 53, chamber S5 and out the opening 520 ' ':~
~n the preferred apparatu~ ~hown in Figure 1 thi~ air i~ not vented .
to outside the buil~ing 10, bu~ rather is recycled a~ preheated .
30 air through co ~ uit 38 because of the ple~um 58 formed by th~ .
do~orative chimney 57........................ . .

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- ~059397 Excellçnt res~lts are achleved ~n the u8e of th~ - r ~
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apparatus of the pre~e'nt lnven~ion to heat a housé~such as- show~ ~' in Figure l wlth 240~ square feet of floor 6pace inol~ding botX
floors and with a thermal reslstance ~actor ~R~ factor o~ tho S att in3ulatlon ln the outside wall~ of 13 and the celling'`of 3~~
which 18 comparable to a well insulated house. ~be exchangèr units 21 and 56 in a fireplace burning wood were able to malntaln-the temperature 1~ the secona floor rooms between aboue 65F ana 70F over a 7 to 9 hour'period a~ter the flre waR ~anXed in'the vening. The flre was banked by pu~tlng a he6 on top of the wood to slow burnlng. ' The advantage~ of the fireplace chlmney furnace ares "
1. The unlt i9 used ln place of a chimney and utllize~
heat that has already escapea the flreplaae, thereby greatly '~' ~
increaslng heat~ng ef~iciency. ;
2~ By supplying combustion alr from outslde the buildin the fireplace can ~unctlon lndependent o~ the heated air in~idé
the house, thus preventlng heat loss through the chlmney. The''~
outside air conduit lends ltself to s~mpllfled dra~t control'whlch increase3 the length of tlme a fire can be ban~ed and held. By uslng out31de air for combu~tion, the flrëplace wi~l funation properly ln a modern, well insulated, tlghtly cohstructea home; ' lthout need of front'opening in the fireplace for combu6tion alr.
nother proble~ i8 that' in a tightly con3tructed bullding with a con~entlonal ~ireplacë the ~lre uses up a~r and begin~ to dle out unle~s out31ae alr ventllation i8 provlded to supply air to th flre. '; ' '

3. The preferred eecondary exchanser 56 funct~on~ mainl~
s an automatlc draft control and chimne~ plpe 47 coollng unit.
~ discussed, the a~r draft ls down when the heat product i~ low nd revers2s up~ard~ as heat bulld~ up in the exchangers. \
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4. The primary exehanger 21 functions equAlly ~ell 1~
¦graVitY f1QW or.forced air.Rystemq~or a eombination thereof. .
~ ~igure 8 illus~rates a variation of the pr~ent invent~or ',i ¦ln a schematic eross.,sectional YieW of a building 100. The 1....~ .,,..
¦bullding includes standard footing~ 101, a first floor 102, out-¦side wall~ 103, l~side walls 10~, ceiling 105 and roo~ 106. a8 with the ch~mney furnaee of ~iqure 1, a ~ireplac~ 107 support~ ~
heat exehanger 108 whieh i~ comprised of multiple tubes 109 throug l which pass the flue g'ases from the fireplace 107. The fireplace l ¦ closed by doors 110 or other elosure means. At the top end of the exchanger 108, a pair of steel flue gas pipe6 111 colleet the flue gases from the exchang~r 108 and vent them to the atmosphere' outside the ~uilding 100. The pipes 111 are supported by ~ , rectangularly cross-sectioned sheet metal box 112 with coolin~ :,.. ,.~ .
vents 113 on t~7c opposing side3 of the box 112. A sheet met~l : ':
eover 114 supports the uppermost end~ of the tiles 111 in th~ .
box 112. A eoncrete or the like cap 115 i~ ~itted over thq'~t~l .cap 114 and extends laterally"away from pipe3 111. 9elow the ~lreumference o~ the cap 115 is a conventional wood ~ramlng 116 20 whlch provides a decorative chimneyAt one side of the framlng 116, are provided an air inlet louver 117. The louver 117 pro- .
vides combustion air to eonduit~ 118 and 119 leading to the bot~om . .
of the fireplace 107. As ean be seen, the ~ents 113 expel warmed alr from the tiles 111 which can be utilized for eombustlon by ..
entry through conduit 118. The condult 118 iB provided with a butterfly valve 119 and ther~ostatle control 120. :'.
In the device of Figure 8, an alr blower 121 18 usqd to feed cold air to the exehanger 108 via condult 122. The air i~ , .: ~' warmed by the tubes 109 in the shell space or ehsmber 123 and , ;, then exit~ via conduit 124 to a plenum 125 between eeiling 105 ~.
and the r-ooF 106. The plenum 125 i8 dueted to the roomts) via ~11-,' , . , ' ~ . ' i , , ~`1 1059397 ~ ~ ~

conduit 126 ln the ceillng 105. ~he plenum ii~' c'oul~ ~ lo-ca~e&--ln any convenlent out of the ~ay ~pace. ~be ~ ~mts~ ar~-pr'ovlded with cold alr return ducts 127 whlch lead to't~e~-~nle~ e ~P-'-: ,, the blower 121. The blower 121 is operated by-a--motos 12~ and S belt 129. ~he operation of the blower motor I28~i~~controlled by thermostaS 130. ~' -- -In operation, the fireplace chimn'ey of ~igure~'~similar to that of Figure 1 except that the plenum 125'store~ --heated air unt~l it is clrculated to the room(s) by the blow~r'~--121. The blower 121 is activated in a conventional manner by th~
thermostat 130 which is attached to the upper part of the exchange 108 and senses the temperature in the chamber 123. The blower :~
turns on when the temperature in the chamber 123~reaches a pr~-selected temperature. ' '~ ~ ------ ~ i ~9 can be seen from the ~oregoin~ descrlption, the,~lre-place chlmney fusnace of the present invention i8 uni~ue in that ~t can be used to replace a conventional fireplaoe chimney an~'"
can be used wlth any type of flreplace. The chimney fur~ace i~
best installed at same time as fireplace but`can be added afte'r-wards by removing and replacing a conventlonal chimney. -'-~'~
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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heat exchanger for installation in a building with a fireplace having a combustion chamber, a front opening leading into a room and having a flue gas exit from the fireplace, as a replacement for a conventional fireplace chimney which comprises:
a) multiple heat exchanging tubes mounted above the flue gas exit of the fireplace such that the flue gases vent upward through vertically oriented openings in the tubes wherein the tubes will extend substantially between at least the exit of the fireplace and a ceiling of a room of the building when installed;
b) a housing surrounding, supporting and enclosing the tubes with at least one opening adapted for attachment to a cold air inlet conduit which leads into the housing from a room of the building and at least one opening adapted for attachment to a hot air exit conduit which leads from the housing into at least one room of the building wherein the tubes and housing are in the form of a heat exchanger unit; and c) cold and hot air conduits adapted to lead from at least one room of the buildings and to be attached to the inlet and exit openings in the housing.

2. The exchanger of claim 1 wherein the cold air inlet is adapted to fit an air blower.

3. In a building with a fireplace having a combustion chamber, a front opening leading into a room and means for closing the opening and having a flue gas exit from the fireplace, the improvement as a replacement for a conventional fireplace chimney with comprises:
a) multiple heat exchanging tubes mounted above the flue gas exit of the fireplace such that the flue gases vent upward through vertically oriented openings in the tubes, wherein the tubes extend substantially between at least the exit of the fireplace and a ceiling of a room of the building;
b) a housing surrounding, supporting and enclosing the tubes except for the openings with at least one conduit from a room of the building for cold air inlet into the housing and at least one conduit for hot air exit from the housing into at least one room of the building wherein the tubes and housing are in the form of a heat exchanger unit;
c) a chimney sealed in gaseous connection with the openings in the tubes and leading outside the building which provides an exit for the flue gases from the tubes of the heat exchanger; and d) an air conduit leading from outside of the building to the bottom of the combustion chamber including a thermostatically controlled valve in the conduit which regulates the amount of air to the chamber.

4. The building of claim 3 wherein the vertically oriented tubes extend above and below at least one floor into two rooms of the building.

5. The building of claim 3 wherein the outside air conduit and heat exchanger housing are enclosed by a separate enclosure from the rooms in the building.

6. The building of claim 3 wherein a second tubular heat exchanger is mounted above the first heat ex-changer such that the flue gases can pass inside the second tubes from the first exchanger, wherein the second tubes are enclosed by a second housing, wherein the air conduit is provided in the second housing such that air can pass around the second tubes and wherein a conduit is provided leading from the second housing to the bottom of the combustion chamber.

7. The second heat exchanger of claim 6 wherein the second tubes are part of the chimney from the multiple heat exchanger tubes.

8. The building of claim 6 wherein the air inlet conduit is surrounded by a plenum formed in a roof top chimney housing.

9. The building of claim 3 wherein the air is circulated across the exchanger tubes and into the room by means of a blower in the cold air inlet conduit adjacent the exchanger housing.

10. The building of claim 9 wherein a plenum is provided in the hot air exit conduit for storage of the heated air prior to operation of the blower.

11. The building of claim 3 wherein the cold air conduit inlet is positioned near the floor and wherein the hot air conduit exit is near the ceiling of the room such that the cold air is circulated across the tubes in the housing, out the hot air conduits and into the rooms continuously by natural convection.

12. The building of claim 11 wherein the hot air conduit directs the heated air leaving the housing upward and into the rooms at an angle of between about 30° to 45° from the horizontal.