Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
787
_CKGROUND OF THE INVENTI ON
The present invention relates to that type of open fire-
place for a living area that embodies a base member, side wall
members, a rear wall member and a flue member, the inner faces of
the base and wall members defining a firebox, said wall members
accommodating an air guiding system therewithin for collecting
and heating fresh air flowing into the living area from a
location external of the living area. The invention more
specifically relates to that type of open fireplace in which the
air guiding system comprises at least one downdraft channel
within the wall members subject to the thermal action within
the firebox enclosure and having its air infeed location at a
higher elevation than its air outfeed location, the air infeed
location being connected to a fresh air location by an ascending
channel.
With most of the previously known fireplaces the
fresh air which is caught externally of the living area is only
conducted through ascending channels; in other words, it
exclusively follows the natural warm air currents.
One advantage of an air guiding system having at least
one downdraft channel over one having only ascending channels
is that the air in the downdraft channel must flow downward
while receiving heat transmitted from the firebox if such air
is to enter the living area. Heated air normally rises, and
such downward motion is only possible if a negative pressure
exists in the living area. With windows and doors closed, as
is normal in adverse weather conditions, there will continuousl~
prevail in the living area owing to the outflowing flue gases
a negative pressure which will draw fresh air from a location
external of the living area into the living area through the
air guiding system. Such inflowing fresh air is heated, during
its inward passage through the air guiding system, unlike
fresh air entering the living area through window and door
cracks. Since the movement of inflowing air through the
downdraft channel must occur from the top towards the bottom,
in other words in a direction opposite to the natural flow
tendency of heated air, a pronounced turbulence prevails in
~9~7~37
--2--
the channel which improves the heat transmission to the air
passing downward therethrough.
Open fireplaces are increasingly less frequently used
as the primary heating system for living areas, and now more
often represent auxiliary heat sources to complement more
extensive heat sources such as central heating systems. Such
fireplaces are often utilized during the spring or fall when
temperature variations do not warrant use of central heat
source. During these transition periods it often times happens
that the living area is not sufficiently sealed to allow the
requisite negative pressure to build up in order to induce
inflow of fresh air through the air guiding system. At such
time, air guiding systems having at least one downdraft channel
are less advantageous than air guiding systems having only
ascending channels in that the latter will induce fresh air
into the living area through the natural flow tendency of
heated air and without requiring negative pressure in the
living area. It would be advantageous if an open fireplace
comprising, in part, an air guiding system having at least
one downdraft channel were developed that could induce fresh
air into a living area without requiring a negative pressure
in the living area.
SUMMARY OF THE INVENTION
Hence, it is a primary object of the present invention
to provide an improved construction of fireplace which does not
have the drawbacks and limitations associated with the pre-v-iously
described fireplaces.
Another and more specific object of the present
invention is a new and improved construction of open fireplace
which would utilize the improved heat transmission capabilities
of air guiding systems having at least one downdraft channel,
and would induce into a living area being heated fresh air
from a location external to the living area, whether or not
a negative pressure existed in that living area.
It has now been surprisingly found that the effective-
ness of the previously-mentioned open fireplace can be considerably
7~37
--3--
increased under both the aforementioned favorable and unfavorable
operating conditions i.e. when a negative pressure is present
in the living area being heated and when such negative pressure
is not present, by connecting the air outfeed of the downdraft
channel to the air infeed of an updraft channel having an
elevated air outfeed into the living area.
Hence, for the purpose of realizing the objectives
of the subject invention, the open fireplace previously discussed,
comprising, in part, an air guiding system having at least one
downdraft channel is improved by the addition, at the air
outfeed location of the at least one downdraft channel, of at
least one updraft channel with an air outfeed into the living
area.
Under the aforementioned favorable operating conditions
i.e. negative pressure in the living area, the updraft channel
is capable of bringing about an acceleration of the air flow in
the living area. Under the unfavorable operating conditions,
i.e. no negative pressure in the living area, the updraft channel
initially receives a relatively small quantity of heated air
at its lower air infeed location, which air ascends, generating
a negative pressure at the lower air outfeed location of the
downdraft channel which in turn creates a sufficient pressure
differential through the downdraft channel to overcome the
natural flow tendency of heated air and result in downward air
flow in the downdraft channel.
According to a particularly preferred construction
of the invention, the updraft channel can be equipped with air
infeed from the living area. Infeed locations may be suitably
arranged, as for instance in the manner of a Venturi nozzle,
to attract air in the living area into the updraft channel at
an elevation below the air outfeed location when a relatively
rapid flow prevails in that channel. If such flow cannot
prevail in the downdraft channel because the heat transfer
thereinto is so great as to overcome the negative pressure
(if any) prevailing in the living area (for instance, if the
windows or door are open there will be no negative pressure),
then at least in the updraft channel an air flow can be created
~L~9~37~7
--4--
to circulate and heat the air in the living area. If the air
infeed location of the downdraft channel is connected with
the fresh air inlet by means of a channel which ascends from
the fresh air inlet, the natural flows of heated air in those
channels tend to counteract one another, creating a certain
stagnation of the flow in the downstream channel which will
prevent air being pumped from the living area into the
surroundings.
Additionally, the subject invention optionally provides
for a lower channel passing under the firebox, having an air
infeed location connecting to a channel extending upwardly to
the fresh air inlet, and having an air outfeed location in the
lower sides of the firebox. Such lower channel allows for
preheating of combustion air.
Accordingly in keeping with the foregoing there is
provided in accordance with the present invention an open
fireplace for a living area, comprising a base member, side
wall members, a rear wall member and a flue member, the inner
faces of the base and wall members defining a firebox. The
wall members accommodate an air guiding system therewithin for
collecting and heating fresh air, such system comprising, a
fresh air inlet, located externally of the living area, a
downdraft channel, subject to heat transfer from said firebox
and having an air infeed, situated higher than an air outfeed,
an ascending channel, connecting said fresh air inlet with
said air infeed of said downdraft channel, and an updraft
channel, subject to heat transfer from said firebox
and having an air infeed communicating with said air
outfeed of said downdraft channel and an air outfeed
communicating with said living area. A further form of the
invention comprises an additional air infeed into the updraft
channel from the living area. A yet further form of the
invention comprises control means for regulating the air feeding
into the updraft channel from the downdraft channel and from
the living area air infeed. A still further form of the
invention comprises, in addition to the basic invention, an
air guiding means connecting the fresh air inlet and the firebox
~13lY7~7
--5--
enclosure. A yet still further form of the invention comprises
control means for apportioning the air entering the fresh air
inlet between the air guiding means connected to the firebox
enclosure and the ascending channel. In still further forms
of the invention, the control means previously mentioned
comprises at least one flap member.
It is contemplated for the practical realization of
the invention that the actual components of the fireplace are
suitably formed of pre-fabricated self-supporting shaped bricks
which collectively provide a load-carrying construction, and
which without any additional expedients, also can form supports
for the smoke channel or flue.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood, and objects
other than those set forth above will become apparent, when
consideration is given to the following detailed description
thereof. Such description makes reference to the annexed
drawings wherein:
Figure 1 is a front view of a first embodiment of a
fireplace designed according to the teachings of the present
invention;
Figure 2 is a side view of the fireplace depicted
in Figure l;
Figure 3 is a front sectional view of the fireplace
depicted in Figure 2, taken substantially along the line III-III
thereof;
Figure 4 is a side sectional view of the fireplace
depicted in Figure 1, taken substantially along the line IV-IV
thereof;
Figure 5 is a perspective view of the different
structural components, partially in section, partly shown
exploded, partly shown assembled, of the fireplace depicted
in Figure l;
Figure 6 is a side view, similar to the showing of
Figure 2, of a second embodiment of the fireplace; and
Figure 7 is a front sectional view of the fireplace
~(~9~787
--6--
depicted in Figure 6, taken substantially along the line
VII-VII thereof.
_ETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 1-5 depict a preferred embodiment of the open
fireplace for a living area which is the subject of this
invention. Figures 1-5 show a base or mounting plate 1, a floor
plate 2, two side portions 3 and 4, a closure plate 5, and a
smoke collecting elementor flue 6 arranged thereabove. These
six elements or components deine the fireplace and form a
supporting frame for the non-illustrated smoke withdrawal
channel or chimney. The fireplace furthermore possesses
two fire bridges or blocks 8 and 9, a partition wall 7 composed
of two plates, a firebox rear wall 10 formed of heat conducting
or transmitting material, a cover 11 for the ash chute and three
regulating flaps or flap valves 12, 13 and 14.
Upon mounting the floor plate 2 on the base plate 1,
there are formed two symmetrically-arranged air guide channels
15 and 16 by means of which the fresh air entrapped or collected
at the rear location 17 is guided directly beneath the fire,
to flow out inwardly directly beneath the fire from below both
sides of refractory blocks 8 and 9, as best seen by referring to
Figures 3 and 5. Since the fire bridges 8 and 9 are markedly
heated by the burning material reposed thereon, the infed air
is heated before it reaches the firebox 10A, and in this regard
attention is directed to the broken lines of Figure 5. The
quantity of such combustion air which is referred to as primary
air can be selectively adjusted or completely closed off by
means of the regulating flap valve 12.
Between the rear wall 10 of the firebox 10a and the
partition wall 7 there is arranged the downdraft or downflow
channel 7', which is connected with.the fresh air inlet 17
by means of the ascending channel 17', located behind the partition
wall 7. By means of the connection channels, 70 and 70', the
downdraft channel 7' is also connected with the updraft or
riser channels, 3' and 4', accommodated in the side walls 3
and 4. The channels, 3' and 4', open via the upper lateral
openings, 3" and 4'' respectively, into the living area.
7t~7
A portion of the fresh air which flows in from the
outside is therefore conducted through this system of channels.
By heat transfer from the firebox this air is heated and therefore
conducted in a heated condition through the openings 3'', 4''
into the living area.
For air to enter the living area through the air
guiding system, the flow through the downdraft or downflow channel
7' must occur from the top towards the bottom, i.e. from the
higher situated air infeed location 7a to the air outfeed
location 7b. The natural upward flow of the warm air current
in downdraft channel 7' opposes this downward movement of the air,
whereas a negative pressure in the room (owing to the operation
of the fireplace in a closed living area) assists this flow.
Also this flow can be regulated by the flap 14. If no or an
insufficient negative pressure exists in the living area this
downward flow will cease, unless there exists a flow through
the updraft channels, 3' and 4', owing to the natural flow of
warm air currents therein.
Since the movement of the air in the downdraft channel
7' occurs from the top towards the bottom, in other words takes
place in a direction which opposes the natural flow tendency of
heated air, there prevails therein a pronounced turbulence and
thus a very intensive heating up of all of the air particles.
Additionally, as the air which is heated in the
updraft channels, 3' and 4', is withdrawn through the upper
lateral openings, 3'' and 4'', air moves downward through the
downdraft channel 7' although there does not exist any or
sufficient negative pressure in the room or the like to create
this effect. Therefore good heating efficiency is practically
always assured.
Since the movement of the air through the channels
with this arrangement is no longer dependent upon a negative
pressure in the living area, inward movement of air through the
channels exists even if all of the windows and doors of the livinq
area are not closed. This constitutes a decisive advantage.
If the fireplace were to exist without the ascending
or updraft channels, 3' and 4', as such was the case with
-8- ~G9~7~
prior art systems and if for instance a window were opened, then
the negative pressure in the room would be immediately cancelled
by the direct inflow of air and the circulation of air in the
channels would either stop or flow in reverse. The infeed of
heated air to the room, which under such circumstances would
be particularly useful, would be suppressed. In fact, it may
happen that air is pumped out of the living area through the
channels, depleting the heat already stored in the material of
the fireplace. As previously explained, with the fireplace of
this invention such behavior is not normally to be feared.
However, situations can arise in which the direct
entrapment of fresh air externally of the living area can not
be carried out, for instance because of wind conditions. In
such instances, there can be employed the second embodiment of
the open fireplace of the subject invention, as shown in
Figures 6 and 7, which operates in the same manner as that of
the first embodiment to bring about a circulation of heated air
in a living area.
It is to be understood that those components of the
embodiment depicted in Figures 6 and 7 correspond with those
components of the fireplace construction discussed above in
conjunction with Figures 1-5 except for the lateral or side
infeed openings into the channels 3' and 4'. Channels 3' and 4'
have been conveniently designated with the same reference
characters.
Hence, also in this embodiment, there is provided the
base plate 1, the floor plate 2, the side walls 3 and 4, the
closure plate 5 and the smoke collector or flue 6.
Furthermore, also with this embodiment, the remaining
construction of the fireplace as depicted in Figures 1-5 has
been found to be useful. However, this embodiment only varies
from the previous embodiment in that it pertains to the interaction
between the fresh heated air, possibly arriving from the non-
visible downdraft channel 7' through channels 70 and 70', and
air from the living area circulating through the channels 3'
and 4'. In order to simplify the illustration and discussion,
g ~L~9~378~
not all of the components of the first embodiment have been shown
in the illustration of this embodiment.
The channel 3' has an inclined opening 30 slanting
downward into the living area, whereas a corresponding opening
40 is provided in the channel 4'.
These openings, if desired, can be closed by the
flaps or flap valves, 31 and 41, respectively, which also can
be advantageously used for closing off the fresh air infeed.
By appropriately setting the flaps, it is possible to control
the ratio of fresh air and circulating air.
For instance, the flaps can be set to shut-off the
entire infeed of fresh air at the start of the heating operation,
so that there exist only ascending or updraft currents in the
channels 3' and 4' brought about by the natural flow tendency
lS of heated air. The flaps can also be adjusted to allow entry
of a desired rate of fresh air infeed. In the case of cold
external conditions, entry of fresh air while the walls of
the fireplace are still cold can be prevented, but it is possible
to utilize the gradually ascending temperature of the fireplace
material for heating the circulating air that enters the updraft
channels, 3' and 4', from the living area.
