Note: Descriptions are shown in the official language in which they were submitted.
2~7888
SPACE HEATER
Technical Field
The present invention relates to furnaces or space heaters. In ~;
particular, it relates to a gas burning space heater having features for promoting
efficient combustion and controlling the temperature of the output whereby the
space heater may be used safely in livestock and poultry barns.
Background of the Invention
U.S. Patent 4,773,848 (to Jalbert and Carver, the latter inventor being the
inventor of the present invention) discloses a furnace for use in the relativelyhostile environment of livestock and/or poultry barns. These environrnents are
hostile in the sense that they contain active animals, animal byproducts, bedding,
feed, chemical disinfectant and treatment agents, and large amounts of suspendedpartiulate matter. The furnace disdosed in the '848 patent has a sealed gas control
valve to shield the valve from the environment.
Breeding and incubation areas or rooms of livestock and poul~y barns are
where heat is particularly needed. Such areas are often small, conflned spaces. This
limited space imposes at least three further constraints on space heaters. First, the
heater unit must be located a substantial distance &om any combustible surfaces or
the output temperature must be lowered from the combustion temperature, about
850 - 1,000 F, to an acceptable level to avoid fire danger. Second, because space
heaters generally are not vented to the exterior of the space in which they are being
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used, high efficiency combus~on is necessary to reduce the level of toxic combustion
byproducts released into the small area. Third, the overall size of the heater should
be minimized to avoid using up vahlable space. It would be advantageous to
achieve a safe, highly e~ficieni agricultural confinement heater that occupies as little
space as possible.
U.S. Patent 3,653,371 (to McManus) is directed to providing a furnace w~th an
L-shaped burner to reduoe the size of the furnace. According to this patent, a burner
mixing tube or duct must haYe a relatively long axial dimension to promote mLxing
the gas and air particles prior to combustion; the longer the tube, the more complete
the mixing and combustion. The burner disclosed in the '371 patent purportedly
enables a smaller furnaoe yet meets the mixing tube length requirement by bending
the tube into two generally perpendicular planes. The disclosed burner also enables
a 180 direction change in the gas flow, purported to provide a stable even flame
across the entire length of the burner and a distribution and diffusion of air and fuel
gas that provides more complete combustion. The heater disclosed in the above~
no~ed '848 patent includes a burner with long tube or neck, generally following the
mL~cing tube length teachings of ~e McManus patent, and therefore is not as
compact as possible.
Other methods of reducing size and ineasing furnace efficiency are lcnown. ;
For example, dampers may be provided in ~he flu or the air-to-fuel ratio may be
precisely controlled. US. Patent 3,280,744 discloses an orifice plate of preselected
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oss section and draft limiting features to control the air-t~fuel ratio and, thus,
promote efficiency.
The space heater of the present invention is small, yet provides high
efficiency combustion. sroadly, this is accomplished by using a eombustion burner
with an inverted (what would normally be thought of as the base of the cone is at
the top of ~e burner), generally flattened frust~conical shape and a gas supply
nozzle having openings or ports designed to direct the gas against the wall of the
burner thereby providing turbulence and thoroughly mixing the gas and
combustion air before igniting it.
U.S. Patents 2,524,047 (to Frese et al.) and 3,850,373 (to Grolitss:h) disclose that
it is known to direct a stream of material against a deflecting surface to accomplish
an objective. However, the Frese et al. patent is directed to an improved fire
extinguishing apparatus wherein a deflecting surface is used to direct a ~e
extinguishing material into a blanket for covering a large area. The Grolitsch patent
is directed to providing a device for atomizing. There is no teaching in either pat~nt
that such devices might be used to mix combustible gas and air to provide more
ef~icient combustion in furnaces.
It would be advantageous if a safe, highly effiaent agricultural confinement
heater that occupies as little spaoe as possible were available.
Summary of the Invention
The present invention provides for a compact yet highly efficient agricultural
confinement spaoe heater. The space heater comprises an exterior shroud, electrical
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and combustion gas control assemblies, a burner, a plenurn or burn chamber and a
blower assembly. Highly efficient combustion is achieved by the bu~ner of the
present invention in combination with the gas orifice. The plenum of the space
heater includes a baffle arrangement, along with air inlets, to insure that the heated
output of the heater is adequately cooled to a predetermined level.
More speciflcally, a preferred embodiment of the burner for the heater of the
present invention is generally frustc~conically shaped having a combustion air
intake opening at its base and an output exhaust slit at its upper end. Oriented
generally vertically in the heater, the burner is flattened, having a height greater
than its width, and does not indude a long gas and air mi~ung tube. A gas delivery
orifice fitting is mounted adjacent the base opening and includes at least two ports,
at least one of which is angularly related relative to the wall of the burner whereby
the combustible gas introduced into the burner from the ports is directed against ~e
wall of the burner rather ~an straight into and linearly up in the direction of the
uppermost discharge slit. This combination produces a turbulent flow of gas and
combustion air rather than a larninar flow thereby creating a homogeneous mixture -
of gas and air and increasing the efficiency of the combustion occurring in the
burner.
Another feature of the present invention is a burn chamber or plenum
having an integral baffle structure whereby the flow pathway of the heated air
through the plenum is lengthened ~o reduce the temperature from approximately
800-1000 F at the burner discharge slit to about 350 F at the heated air outlet of ~e
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heater. Additionally, the plenum includes at least one, but preferably two,
ventila~ng cool ambient air inlets along the pathway to further cool the heated air
before it is discharged into the environment.
An object of the present invention is to provide a space heater for agricultural
confimement areas typically found in livestock or poultry breeding barns, for
temporary heating at construction sites, or for garages.
Another object of the present invention is to provide a compact space heater
having a burner and gas delivery orifice for delivering fuel to the burner, the burner
and orifi~e combination producing highly efficient combustion, and having a
plenum or after-burn chamber for providing a hot air flow path which cools ~e hot
air from the combustion temperature to a predetermined standard level safe for
both livestock and the structure housing the space heater.
Yet another object is to provide a space heater operable on nahlral, butane ar
propane gas at various pressures and flow rates, at various altitudes or atmospheric
pressures and to produce a selected output temperature.
Still another ob~ect of the present invention is to provide a space heater
having a burner, a plenum burn chamber and a blower assembly wherein the
blower assembly induces the flow of combustion air into the heater, enhances the
turbulent mixture of combustion gas and combustion air within the burner, and
rapidly moves the heated air through the plenum.
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Other obj~ts, features and advantages of the present invention will become
more apparent and understood with reference to the following specification and to
the appended drawings and daims.
Brief Description of the Drawings
Fig. 1 is a perspec~ive view of the heater of the present invention; :
Fig. 2 is a fron~ elevational view of the heater with parts cut away to reveal
the heated air flow path through the heater; ~ ~
Fig. 3 is a sec~onal view thereof taken along line ~3 in Fig. 2; ~ ::
Fig. 4 is a right side elevational view of the burner of the heater of the present
invention; :~
Fig. 5 is a front elevational view of the burner;
Fig. 6 is a top plan view of the burner, depicting an alternative exhaust slit in
phantom;
Fig. 7 is a elevational view of the gas orifice fitting of the present invention; -~
Fig. 8 is a top plan view of the orifice;
Fig. 9 is a sectional view taken along line 9-9 in Fig. 8;
Fig. 10 is a top plan view of an alternate embodiment of the orifice having
additional gas emitting ports; and
Fig. 11 is a elevational view of the orifice depicted in Fig. 10.
Detailed Description of the Preferred Embodiment
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ReferIing to the draw~ngs, a direct gas-fired circulating space heater 14 for use
in agricul~ural buildings includes a heater body 15, electrical and fuel control
assemblies 16, and a burner assembly 18.
Referring particularly to Fig. 1, the space heater 14 in accordance with the
present invention indudes an exterior heat-shielding casing shroud 22 with
detachable ent panels 24, 26. The shroud 22 is connected to a heater base plate 30
and supports a hot air discharge assembly 32 and an electrical power supply junction
box 34. A sealed gas valve box 36 is also supported by the base 30 and shroud 22. The
shroud 22 is removable from the base 30 for servicing, and the end panels 24, 26 are
removable from the shroud. The end panels 24, 26 may be provided with plurali~y
of apertures 38 creating a grill effe~, and at least one of the end panels, panel 24, does
not entirely occupy or close the end of the heater 14, thereby leaving an air inlet and
access opening into the heater.
The outer shroud 22 of the heater body 15 provides an outer heat shield skin
and may be formed of appropriate gauge stainless steel, galvanized or aluminized
steel, or other appropriate materials. Referring to Figs. 2 and 3, ~e shroud 22
provides an interior cavity for containing a combustion burn chamber or plenum
40. The plenum 40 preferably is forrned from 20 gauge stainless steel, although
other appropriate gauges and material may be used as well. The plenum 40 may be
fabricated as a stand alone, walled unit and mounted to the bottom base 30 in an
appropriate fashion, or it may be formed integrally with the base 30, as an extension
thereof. The plenum 40 is spaced inwardly from the outer shroud 22 to provide an
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air space 42 for insulation purposes and air flow and heat exchange purposes. Atone end the plenum 40 includes ambient combustion air inlet opening 44, and at
the other end has a heated air output opening 46. The plenum 40 also includes anauxiliary ventilating or cooling opening 48 in the rear wall and a second such -
opening 50 in the bottom wall. A first integral baffle defle tor plate 52 is fixed in the
plenum 40 generally perpendicular to the air flow from the inlet 44 toward the ~ ~
output opening 46 (the flow is depicted by a plurality of arrows in Figs. 2 and 3). A ~ ;
second larger baffle deflector plate 54 is also in the plenum 40 and is generally
perpendicular to ~e first baffle plate 52.
A blower assembly 56 is mounted on ~e base 30 at the end of the plenum 40
opposite the intake 44. The blower assembly 56 is generally contiguous with the end
wall of the plenum 40 carrying the outlet opening 46. The assembly 56 includes a -
blower motor 58, a blower housing 60 and a "squirrel cage" impeller or blower 62mounted in the housing 60 and operatively connected to the motor 58. The blower
assembly 56 generates a negative pressure inside the plenum 40 and creates the
heated combustion air flow depicted by the arrows in Figs. 2 and 3. It should beappreciated that the deflector baffle plates 52, 54 contribute to the cooling of the
heated combustion gases by providing a labyrinth or convoluted flow path.
Additional cooling of the hot combustion gases is provided by the ventilating air
drops or openings 48, 50 in the walls of the plenum 40.
Referring back to Flg. 1, the burner assembly 18 of the heater 14 of the presentinvention includes gas lines 64 connected between a comrnercially available gas
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control valve 66 (depicted in phantom) and a single hexagonal burner orifioe fitting
68 mounted adjacent the base 30.
Referring to Figs. 7-11, the burner orifice 68 includes a body 70 having a
generally central bore or cavity 72. One end 74 of the orifice body 70 is threaded to
accept a gas line 64, as usual. Adjacent the opposite dosed end 76, the orifice body 70
is provided with individual drilled gas ports 78. The ports 78 are drilled at a specific
angle relative to the orîfice longitudinal axis (i.e., 70, as shown at angle B in Fig. 7~.
Figs. 10 and 11 depict another embodiment of the burner orifice fitting 68'.
The second embodiment 68' is substantially similar to the embodiment 68 depicted
in Fig. 78, but includes more gas ports 78', four are depicted. In this fitting
embodiment 68', two ports 78' are dril~ed at angle C, pre~erably 70, and the two ports
78' closest to the threaded inlet end 74 are drilled at 90. The use of ei~er the two
port orifice fltting 68 or the four port orifice fitting 68' relates to the type and
pressure or input rate of the gas fuel being used. The orifice ffttings 68, 68' are
preferably formed of brass but other suitable material may be used as well.
Referring to Figs. 4 6 the burner assembly 18 includes a burner 80. The
burner's position relative to the heater 14 is represented in at least Fig. 2. The
burner 80 includes mounting structures 82, 82' for connecting it to the end wall of
the plenum 40 with customary fasteners. The bumer 80 has an inlet end 84 and an
output or combustion exhaust end 86. The inlet portion 84 is immediately adjacent
to the orifice 68 and is substantially open to receive ambient air, drawn inwardly
into ~e plenum 40 by th~ blower assembly 56. The flow of arnbient air is depicted at
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arrows F in Fig. 2. At its upper outlet end 86, the burner 80 indudes a hot
combustion air discharge slit 88, ~est seen in Fig. 6. A second embodiment of the ~ :
burner 80, wherein the sli~ 88' is narrower than the slit 88, is depicted in phantom. ~ v
Between the inlet end 8~ and the exhaust end 86, the body 90 of the burner 80
defines the actual burning chamber. The burner is generally frusto-conically shaped,
yet flattened near its upper end 86. The burner wall forming the body 90 comprise~
basically a single continllous surface tapering upwardly and outwardly away fromthe inlet end 84 in one orientation (see Fig. 5~, and tapering inwardly and upwardly
in the orientation depicted in Fig. 4. Referring to Fig. 5, mounting apertures 92 may ::
be provided on the flat sides of the burner 80 for connecting appropriate monitoring
or aw~ciliary equipment to the burner 80.
Additional components and controls such as meters, control switches and
sensors, specific electrical components, specific gas conduit components and bumer
components are commercially available and installed or used in their customary :
fashion, as disclosed in U.S. Patent 4,773~848, the disclosure of whi~h is incorporated
herein by reference. An example of such an additional component is a second hightemperature limit switc~ similar to the type used with the furnace disclosed in the
'848 patent.
In use, gas flows in response to thermostat control, and from the orifice 68
through the ports 78 as depicted in Figs. 4 and 5. The blower assembly 56 acts to pull
ambient air for combustion purposes into the inlet end 84 of the burner 80 and into
the plenum 40 in the direction of arrows P depicted in Fig. 2.
2a~r~s~s
One of the objectives of the present invention is advantageously achieved by
the orifice fitting 68 and the angled Forts 78. This advantage is depicted in Fig. 4
wherein gas being adrnitted into the burner 80 from the port 78, along with ambient
air, is directed against the wall of the burner 80. As suggested by a~Tows D in Fig. 4,
the impact of the gas on the wall redirects the gas and produces a turbulent flow
toward upper end of the burner 80. The turbulence is increased as ambient air isdrawn inwardly by the blower assembly 56, thereby producing inside the burner 8û a
thorough mix of ambient air and gas. The result is very efficient combustion
producing exhaust gases with a carbon monoxide level of 6-12 parts per million
(ppm)-
With regard to the second embodiment of the orifice fitting 68' depicted inFigs. 10 and 11, the number of ports 78' in the orifice fitting 68' depends on the type
of fuel being used (natural gas, propane gas, or butane gas), ~e desired heat output
(in BTU's) and the atmospheric pressure.
The width or size of the exhaust slit or opening 88 (or 88') at the top of the
burner 80 as depicted in Fig. 6 is a variable feature and contributes to ~e efficieng of
the heater 14. The size is selected relative to the desired output, the fuel, and to
insure that there is no backdown burn inside the burner 80.
The objective of producing a space heater for use in confined areas is
accomplished in the present invention in large part due to the design and features
of the plenum 40. Specifically, with reference to Figs. 2 and 3, initiating the blower
assembly 56 produces a negative pressure in the plenum 40, drawing ambient air
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and the heated combustion a,r into the plenwn 40. The flow of heated combustion
air is along a convoluted air flow path. The blower assembly 56 also draws
additional ventilating or cooling air through the air inlets or air drops 48, 50. These
features enable the heated combustion air, at approximately 80~1,000 F at the top of
the burner 80, to be cooled to a temperature less than 350 plus ambient temperature
at the discharge duct 32. An additional feature that contributes to the safe use of the
hea~er 14 in small areas is that the outer heat shield shroud 22, and particularly the
way the plenum 40 is set inside the shroud 22, eliminates "hot spots" on the heater
14.
The heater 14 of the present invention includes several models based on
desired heat output (in l~rU's). For all models of the present invention,
commercially available components, some of which (e.g., the burner) may be
specifically designed, include:
Burner Single piece cast iron
Combination Control Robertshaw model 7200ERR3 or
Honeywell model VR8300
Air Proving Switch Micro-Switch (Honeywell)
rnodel V3L-3287-D8
Transformer Basler Electric, Class lI, 12~24V
High Lirnit Switch Therm~disc model L3SOP
Ean Motors General Electric model 5KCP39EGL418S
General Electric model 5KSP29FG-7321S
Pilot Assembly Robertshaw model HS780
Electronic Ignitors Carbo model 0206FC007
Norton model 271
Electrical & Gas Control Enclosures Freeman Chemical Corp.,
polyurethane plastic with foam seals
Data and specifica~ons of one selected model of the heater 14 are as follows
Model 60 Natural Gas PropaneGas
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Max. Input Rating (Btu/hr) 60,000 60,000Min. Input Rating (Btu/hr) 28,000 32,000Manifold Pres. - High (in.wc/kPa) 5.6/1.39 11.0/2.74
Manifold Pres. - Low (in.wc/kPa) 1.5/.37 3.3/.82
Port Size (DMS) (4) #50 (2) #56 (2) #57
Max. Inlet Pres. (in.wc./kPa) 7.5/1.87 14.5/3.61
Min. Inlet Pres. (in.wc/kPa) 5.5/1.37 11.8/2.93
It should be appreciated that the heater 14 may be adapted to be used with
various fuels, atmospheric pressures and fuel flow pressures (e.g., by changing the
number and size of the ports, by changing the horsepower of the blower motor, etc.).
The preceding table is intended to be exemplary.
The space heater 14 of the present invention might take different forms
within the scope of the invention. The outer configuration of the heater 14 may be
changed; various peripheral items such as additional sensors or warning indicators
for blower malfunction, overheating or appliance malfunction may be provided; a
timed post-bum purge feature may be incorporated with the blower assembly 56; the
material for forming the heater body 15, the plenum 40 and the burner 80 may be
selected from appropriate materials; mounting features such as apertures in the top
of the shroud æ may be provided to hang or otherwise mount the heater 14; and
various indicia or instruc~ons for the mounting, operation and safety may be
provided on the exterior surfaces of the heater 14.
It will be seen that a cost effective, safe and efficient method of heating areas is
provided by the space heater of the present invention. The invention may be easily
installed in existing buildings or it may be used in new construction.
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The present inve~tion may be embodied in other specific forms without : :
departing from the central attributes thereof. Therefore, it is desired that thedescribed embc~iments be considered in all respects as illustrative and not
restrictive, reference being made to the appended claims rather than to the foregoing
description to indicate the scope of the invention.
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