Note: Descriptions are shown in the official language in which they were submitted.
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Case 2860
COMBINED RADIANT A~D FAN HEATER
This invention is directed to an electric
heater, primarily of the portable type.
Portable electric heaters are well known and
highly developed, and generally fall into one of two
the classes, namely a radiant heater or a space area
heater, using forced convection means.
Radiant beater~ o~ the quartz eleMent type
have recently impacted the market, and because o~
thair relatively local e~ect are used primarily as a
personal heat source. Portable space heaters are also
well known and widely used, most usually ralying upon
a fan effecting a significant dispersal of heate~ air,
to function as a space area heater.
Certain types of radiant heaters have in the
past utilized a small capacity fan providing local
circulation, as a means for recirculating air past a
thermostat such that in the event the front of ~he
heater becomes obstructed, or is placed in too close
proximity to a barrier, then the temperature of the
recirculated air will rise quite rapidly, causing the
protective thermostat of the heater to de-energize the
heating element, by disconnecting the electrical
connection thereto.
The present invention makes provision for a
fan means having at least two modes of operation,
namely a slow speed mode, as described above fox prior
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a~t radiant heaters, whereby the temperature of the
radiant heating means remaIrlS substantially
undiminished and the heater functions in the same
fashion as other personal radiant heaters. In the
other mode, with high speed fan operation, this causes
dispersal of heated air generated by th,e radiant
heating means, so as to effect space area heatin~.
This hot air disperal is effected such that the
temperature of the radiant heating means is
significantly reduced with a marked reduc~ion, in heat
radiation.
It has been found that the purposes o-f two
quite different heater types m~y be combined into a
single entity, giving the benefits of being able to
operate in two quite disparate heater modes, whilst
achieving respective outputs in each mode of operation
that compare closely with commercial products of the
respective type.
In accordance with the present invention
there is thus provided a multi-mode fan heater having
a radiant element, reflector means for reflecting heat
radiated by the element, operable in a first mode
wherein the heater functions as a personal radiant
heater, fan means operating at a high capacity in a
second mode of operation of the heater to
significantly cool the radiant heating means and to
effectively disperse air heated by the heating means
in space area heating relation.
A preferred embodiment of the invention
incorporates fan means including a speed control
switch for selecting the mode of operation of the
heater~ The speed control switch includes a low speed
fan setting for operating in a first, radiant heating
mode to provide limited local air recirculation within
the heater, having thermosensitive control means for
sensing the temperature of recirculated air, being
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Case 2860
connected electrically in energy controlling relation
with the radiant element, to limit energization of
that element when a predetermined air temperature of
recirculated air is sensed.
In the preferred embodiment a generally
parabolic reflector is provided having an extended
lower leg extending to~Jards the front of the heater,
in order to eliminate any undue floor heating effect
which can otherwise constitute a fire hazard. The
reflector is provided with an air outlet slot or slots
substantially horizontally aligned behind the focus of
the reflector, so as to discharge air in cooling
relation over a radiant heating means such as a
resistance heater located at the reflector focus.
The reflector is provided wi-th an air inlet in the
upper half thereof for recirculation of heater air,
there being a thermosensitive sensing element being
located in the path oE the air flow, behind ~he
re~lec~or and electrically connected in series
relation with the energi~ing circuit of the radiant
heater.
The fan is fitted for dual mode operation
having control means for switching the fan from a high
capaci~y blowing mode to a low capacity blowing mode.
The dual mode function is generally provided by a
multi-speed controller for the fan motor, having a
selection switch by means of which a predetermined
mode of fan operation is ~elected.
Selection of the low capacity blowing ~ode
causes a low volume of air to circulate past the
radiant heating means, so that the temperature of the
radiant heating means is maintained at a high value,
and the heater functions effectively in a radiation
mode. Selec~ion of the high capacity blowing mode
causes a high volume of air to circulate past the
radiant heating means, thereby dropping its
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Case 2860
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temperature, so as to diminish the radiant output
therefrom, while causing the apparatus to dissipate
heat primarily by means of hot air dispersal, in a
space area heating mode, whereby heat is tran~ferred
away from the proximity of ~he heater, in room heating
relation.
In the case of operation in either mode
where the circulation of air is impeded such that a
dangerous temperature rise can en~ue, such for
instance as the entrainm~nt of curtains at the heater
air inlet or outlet, or the positioning of the heater
in dangerously close proximity to an object, the
consequent diminuation of air flow results in a
significant rise in the temperature of air entering
lS behind the reflector. This raises the temperature of
the thermosen~itive ~ensor to a sufficient extent to
limit or cut off the energization of the heater
element.
Certain embodiments are described, reference
being made to the accompanying drawings wherein:
Figure 1 is a general view of a portable
heater incorporating the present invention;
Figure 2 i5 a section end view taken at the
plane 2-2 half-way along the heater, and
Figure 3 is a view corresponding to Figure 2
of an alternative embodiment.
Referring to Figure 1, the heater 10 is a
portable appliance having a cabinet 12 with a pair of
end walls 14 and an enclosure wall 16~ A protective
grill wire 18 isolates a radiant heating me~ns 20,
illustrated as a metal rodded heating element of the
type trademarked CALROD, the heating means 20 being
mounted at the focus of a generally eliptical
reflector 22 having an elongated lower leg portion 24
that serves to limit reflected or directly radiated
emission on to the floor or other supporting surface.
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Case 2860
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A fan 26 driven by electric motor 28 and
provided with selection switch 30 operates in a two or
a three speed mode, to circulate air heated by the
heating means 20. In the Figures l and 2 embodiment
air drawn through the fan 26 is blown through slots 32
of reflector 22 in heat ~ransfer relation with the
heating means 20. A return flow of heated air enters
past the reflector 22, by way of slots 34 therein, the
temperature of the return air flow being sensed by
thermosensitiv~ control means 36 having a control
knob 38. The control means 36, being in the preferred
embodiment a bimetallic thermostat, is co~mected in
series switching relation with the energization
circuit of the heating means 20.
In operation, with the heater plugged in by
way of cord plug 40 to a suitable outlet (not shown~
and the con~rol ~wi~ch 30 set on a low speed ~ix1t
mode o~ opexation, the rate of air ciculation by the
fan is sufficien~ly low -that the temperature of the
heating means 20 becomes sufficien~ly high as to
function as an effective radiator, whexein the heat
generated by the heating means 20 is predominantly
reflected forwardly of the heater l0, by means of the
reflector 22, whereby the heater may be used
effectively as a personal radiant heater.
Operating the heater l0 in a second mode
with the fan central switch 30 set for a higher speed,
the throughput of air is sufficient to cool the
heating means 20 to the extent that it is no longer an
efficient radiator, and the heat output is dispersed
as hot air, by the fanO The heater l0 thus operates
in the second mode as a space area heater.
Turning to the Figure 3 embodiment, the
fan 26' is arranged to draw air heated by the heating
means 20 rearwardly through slots 31, for discharge by
the fan 26' forwardly through outlet 42 located at
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Case 2860
the front of the heater 10. In this arrangement the
thermosensitive control means 36 is located adjacent
the slot 31O
Reverting to the Figure 2 embodiment, this
arrangement lend~ itself to ~he provision of an air
filter 4~ through which air circulates forwardly
particularly in the high speed or space area heater
mode of operation.
In simulated performance tests, carried out
under typical operating conditions, and comparing the
performance of the subject heater with that of another
brand, when functioning in the "mode 1" low throughput
fan operation, as a radiant heater, virtually
identical radiant heating was achieved as provided by
a typical radiant heater of the type utilizing a
quartz heating element.
Operating in the second mode as a spaca a~ea
heater, the ~ubject heater took the same time to heat
an enclosed space as that required by a commercial
portable space area heater, to heat the same space to
the same extent.
Thus, the operation of an embodiment of the
multi-purpose heater of the present invention in
either of its selected modes has been found to be
virtually identical in each instance to a specialty
heater designed to operate solely in that particular
mode.
Thus, from actual results:
1) Mode 1 - radiant heater: heating a
simulated "person" at a dista~ce of 3 feet,
to effect a temperature rise from 10C
to 20C, the subject heater required 9
minutes 11 seconds. A quartz radiant heater
required 9 minutes 16 seconds to perform the
same heating.
2) Mode 2 - space area heater: heating a room
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Case 2860
10 feet x 8 feet by 9 1/2 feet high from
10C to 15C required 12 minutes 30
seconds. A competitive fan heater, for the
same effect also required 12 minutes 30
~econds.
The subject heater thus presents a dual
capability normally provided only by two separate
heaters.
It should be emphasized that mis-using
heaters to achieve the "other" function lead~ to the
following results:
1 ) using all equivdlent radiant heater,
operating in the manner of a space area
heater, to heat a room requires 33~ more
time than using the subject heatsr when
operating in i~s space area heater mode~
2~ operating the subject heater in its ra~iant
heater mode permits heating a "per~on" in
half the ti~ne required by an equivalent
~0 space heating fan heater.
Thus~ it will be seen that the ~ubject
invention makes readily available the selec~ion of the
most effective mode of heating for a given situation,
at the touch of a button, using a single portable5 heater.
The adoption of this invention also permits
the use of a wide range of styling formats of
acc~ptable efficiency and attractive appearanceO
