AIR FURNACE

APPAREIL DE CHAUFFAGE AVEC ECHANGEUR DE CHALEUR A CIRCULATION D'AIR

English Abstract

ABSTRACT OF THE DISCLOSURE
An air furnace adapted to burn wood, of the type in-
cluding air heating tubes mounted in the combustion chamber,
and characterized by being arranged to optimize the heat
transfer with up and down flow of the hot combustion gases
around the air heating tubes and adjustable flows of am-
bient air in it to control the temperature of the ambient
air. The air furnace includes an inner firebox casing for-
ming a combustion chamber having air tubes in its upper
portion, an outlet for combustion gases and smoke in one of
its walls, a baffle secured to that one wall to form an
upwardly opening pocket cooperatively with the same in
registry with that outlet and outer casing, and dampers
between the walls of the firebox casing and outer casing to
control flows of ambient air between the two casings.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED, ARE DEFINED AS FOLLOWS:
1. An air furnace comprising: a firebox casing enclo-
sing a fire chamber with the latter defining a bottom combus-
tion portion and a top heat exchanging portion; at least one
pass of air heating tubes mounted in the top heat exchanging
portion in contact with combustion gases rising into the latter;
the firebox casing having an outlet for combustion gases pro-
vided in a wall thereof and positioned intermediate said top
and bottom portions; and a baffle positioned inwardly relative
to the outlet for the combustion gases and cooperatively for-
ming with said wall an upwardly opening internal pocket cons-
tructed and arranged for downward passage of the combustion
gases therethrough toward exit through said outlet.
2. An air furnace as defined in claim 1, further com-
prising an outer casing surrounding the firebox casing, having
side walls laterally spaced from corresponding side walls of
the firebox casing, cooperatively forming upward air passages
therewith, and having air inlet means and air outlet means at
the bottom and top respectively constructed and arranged for
upward flow of ambient air into said upward air passages, and
an adjustable damper mounted into each of the upward air passa-
ges and selectively controlling the upward flow therein.
3. An air furnace as defined in claim 2, wherein each
of said corresponding side walls of the firebox casing includes
a lower wall portion in direct contact with the correspon-
ding upward air passage and combustion chamber on the outer and
inner sides thereof respectively and firebricks are laid against
the inner side of each corresponding side wall above said
lower wall portion.

4. An air furance as defined in claim 3, wherein said
casings define a front wall, said upward air passages are
positioned on the opposite lateral sides of the firebox casing,
and an adjustment handle is connected to each of the adjusta-
ble dampers and outwardly from the front wall.
5. An air furance as defined in claim 1, 2, or 4, wherein
the air heating tubes include two passes of tubes mounted in
the top heat exchanging portion, an intermediate air chamber
joining one end of said one pass of tubes, and an external air
inlet and an external air outlet is connected to the other end
of said one and other passes respectively.

Description

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FI~LD OF THE INVENTION
mi8 invontion rolate~ to an alr furnac- in particu-
lsr of the type in which air 1~ heatod in air pa-~age tubo~
mounted ln the co~b~stion chamber.
DESCRIPTION OF T~E PRIOR ART
Up to th~ pr~sont, various oth r concopt- of furnw-s
of tho ~bovo typo hav~ been propos-d but no~e wa- found ~p--
cifically adapted to burn wood in it ~ith opti~izod hoat
tra~sfor.
SUMMARY OP TB INVENTION
It i~ a gen~ral obj~ct of the present in~ention to pro-
vidc an air furnace of the above typc that i8 adapted for wood
burnlng and arranged to optimize the heat transf~r.
It i~ an obpct of the pre~ent inv~ntion to provide an
air furnace of th~ abovo type that includes an up and do~n
flow of the hot combustion ga30s around the air passag~ tubes
before its exit into tho chi~noy to enhanco the heat transfer
botw~en the hot co~bustion ga~es and the air in the air pa~age
tubes.
It i8 another object of th~ pre~ent invention to provido
an air urnace of the above typo that i~ arranged to heat
flow~ of ambient air through it and to adjust the amount of
a~bi~nt heating done by such ~ln~ of ambicnt air in it.
BRIEF DESCRIPTION OF TB DRAWINGS
The above and oth~r objects and advantage3 of the present
invention will be bettor undorstood ~ith roferenco to the
following d~tailed dowription of a preferred e~bod~Qnt thor~of
which is illu~trated, by way of ox ~pl~, in the accoypanying
drawingg; in which:
Piguro 1 i~ a porapectivo viow of an air furnaco according
to tho pros~nt invention;
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Figure 2 is a top plan view of the same air furnace
with parts broken away to show the arrangements of air tubes
in it;
Figure 3 is cross sectional view of the Aams furnace taken
transversely to it;
Figure 4 is a longitudinal cross section of the same
furnace; and
Figure 5 is a partial view illustrating a damper to control
heating of the ambient air.
DETAILED DESCRIPTION OF A PREFERRED EMOODIMENT
The illustrated air furnace includes a firebox casing 10
defining a fire chamber forming a bottom bombustion portion 11
and a top haat exchanging portion 12. The firebox casing
includes an outlet 13 in its rear wall 14 for the combustion
gases and smoke which escape through smoke duct 44. A baffle
15 is fixed inside the firebox casing 10 inward of the outlet
13 to cooperativsly form with the rear wall 14 an upwardly
opened pocket at 16. The latter has its upper end opening
in the heat exchanging portion of the combustion gases.
The bottom of the firebox casing 10 is formed with an ash
pit 17 covered by a movable grate l~ having handle lOt.
A pan 19 is removably inserted under the grate l~ in the ash
pit 17, as shown by the dotted lines in Figure 4.
In the heat exchanging top portion 12 thare is mountsd
B horizontal baffle 20 and a partition 21 extending between
the baffle 20 and the top wall 22 of the firebox casing 10
to divide that heat exchanging top portion into two laterally
adjoining compartments. Air passags tubes 23 extend hori-
zontally in those two adjoining compartments and project at
one end through the rear wall 14 and at the other end through
a transverse partition 24 extending inward of the front wall
25 and cooperatively forming with it an intermediate air
chamber joining the forward end of the tubes 23 in one compart-
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m~nt to th~ forward end of the tubes 23 in the laterally adjacent
compartment. There are thus formed two passes of air hsating
tubas 23 in the heat exchanging top portion 12 o~ the combus-
tion chambsr. An air inlet maniPold 26 and an air outlet mani-
~fold 27 are connected to the rear end of the tubes 23 of ths
two passes respectiuely. The air inlet mani~old 26 i8 provided
with a tubular air inlet 28 in which iq installed a fan unit 29
for forced air circulation in the air heating tubes 23. The air
may thus be forced to circulate through the sir tubes and thus
ths air furnace can so heat the ambient air or the air in some
other room or space. Domestic hot water may be produced in a
water pipe 30 looped through a pair of air tubes 23. An accsss
plate 31 is removably secured over an access aperture in the
front wall 25 to give access to the air tubes 23.
A door 32 is hinged to the front wall 25 and is tightly
closed by a handle 33 having a latching projsction 33l anga-
ging an appropriate catch 33" upon pivoting of the handle.
Ths front wall 25 is releasably secured by a pair of rsmov-
able nuts 34.
The inner firebox casing 10 includes a pair of opposite
side walls 35 inwardly spaced from a pair o~ outer side walls
36 respectively with the latter forming an outer cssing.
~etween the side walls 35 and 36 on each side of the furnace
thsre is thus formed an upright air paesage opened both at
the bottom and at the top for free circulation of ambient air
through ths bottom air inlst and top air outlet thus formed.
An adjustable damper 37 i9 pivotally adjustable in each of those
upright air passage to adjust the flow of ambient air in the
latter. An adjustment handle 38 is secured on the outwardly
projecting ~nd of each dampsr piuot~ that is, outward of the
front wall 25 to readily adjust sach damper 37. A few cavities
39 are provided in the front wall for selsctive sngagsment in
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ons of thsm of a pin sscured to ths corrssponding handla. Such
pin and cavities allow to positively adjust the angular setting
of ths dampers 37 in one of a predetarmined number of angular
positions~ as best shown in Figurs 5.
Fire bricks 40 are laid against the inside of only the upper
portion of each side wall 35 such that the lower portion of
each side wall is in direct contact with the ambiant air flow
and with ths fire to enhance the heat~transfer to the ambient
air flow.
An adjustable trap 41 is provided in the fira chamber just
inward of door 32.
When starting the ~ire, a better draft is obtained by
opening the damper 42 in by-pass 43 of the smoke duct 44 and
by closing damper 45 of smoks duct 44. Oy-pass 43 communi-
catas with opening 46 in top wall 22 with top portion 12
and therefore smoke can rise directly into the chimnay.
Whan sufficisnt draft has bean produced, dampar 42 is
closed snd dampsr 45 is opened.