Note: Descriptions are shown in the official language in which they were submitted.
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M6~& 7710.1--CA-01
ELECTRIC THERMAL S ORAGE HEATING UNIT
Field of the Invention
The invention relates broadly to space heaters. More
specifically, the invention relates to electric thermal
storage space heaters.
Backqround of the Invention
Electric space heaters, because of their safety and
convenience, are a popular means of heating commercial and
residential living space. One type of electric space
heater recently introduced into the market is the
electrical thermal storage (ETS) heating unit. ETS
heating units are particularly useful when the cost of
electricity varies during the day (off-peak rates) because
they can generate and store heat when the cost of
electricity is low and use the stored, low-cost heat when
the cost of electricity is high.
Typical ETS heaters include a heat sink surrounded by
an insulated housing; at least one duct through the heat
sink and housing for allowing surrounding air to be
circulated past and heated by the heat sink; an electric
heating element within the housing for generating heat; a
fan for circulating air through the ducts; a thermostat
for measuring the temperature of the space to be heated
and controlling operation o~ the fan accordingly; and a
thermostat ~or measuring the temperature of the heat sink
and controlling the amount of heat stored in the heat sink
by controlling operation of the heating element. While
the heating unit requires a thermostat to measure room
temperature in order to properly control the operation of
the fan, these thermostats are typically not supplied by
the manufacturer but are readily available to the consumer
at many retail outlets.
Normal wear and tear of typical ETS heaters requires
that the heating elements be periodically replaced.
Unfortunately, the heating elements in typical ETS heaters
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are placed within the heat sink and the housing such that
in order to replace the heating elements it is necessary
to remove a portion of the housing, a portion of the
insulation, and all or a portion of the heat sink; making
the repair of worn heating elements in typical ETS heaters
difficult and time consuming. Further, each time the
insulation is disturbed in order to repair the heating
elements the integrity of the insulation is destroyed and
its insulating value decreased.
Accordingly, a need exists for an ETS heater designed
to allow worn heating elements to be quickly and easily
replaced without adversely affecting the integrity of the
insulation.
Summary Qf the Invention
An electric thermal storage (ETS) heating unit which
allows the heating elements to be quickly and easily
replaced with minimal disturbance of the other components.
The ETS heating unit comprises: (a) an insulated housing
having at least one lateral linear opening at the bottom
thereof and defining a storage chamber; the housing having
sufficient clearance underneath so as to permit a heating
element to be inserted or removed from the bottom of the
housing; (b) a plurality of heat sink bricks configured
within the storage chamber ~o as to form verti¢al ducts
which extend substantially vertically above the lateral
linear openlngs and horizontal ducts which interconnect
the vertical clucts 80 that air external to the storage
chamber can be drawn into a first vertical duct,
circulated past the heat sink bricks and returned external
to the chamber through a second vertical duct; (c) at
least one substantially planar, serpentine, electrical
heating element having an upper, heat-generating portion
extending into a duct and a lower, connecting portion
extending out of the storage chamber through the linear
opening; the upper portion of the heating element lying
within substantially the same plane as the linear opening
such that the heating element may be inserted into and
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removed from the storage chamber through the linear
opening without significantly disturbing the bricks or
the housing; (d) a means for circulating air through the
ducts; (e) a temperature control means for measuring the
temperature of the space to be heated by the unit and
controlling the circulation of air through the ducts in
relation to the air temperature; and (f) a means for
measuring the temperature in the storagei chamber and
controlling the flow of electricity to the heating
element in relation to the storage chamber temperature.
The heating elements may be quickly and easily
replaced by electrically disconnecting the heating
elements, slipping the heating elements out of the
storage chamber through the linear opening, slipping a
new heating element into the storage chamber through the
linear opening, and electrically reconnecting the new
heating elements. It may be necessary to remove
components below the housing such as the grill, the
intake vent, etc. in order to remove the heating
elements, but it is not necessary to disturb either the
housing or the heat sink bricks.
Other aspects of this invention are as follows:
An electric thermal storage heating unit,
comprising:
(a) an insulated housing having a bottom wall with
at least one laterally extending, linear opening; the
housing defining a storage chamber;
(b) a plurality of heat sink bricks configured
within the storage chamber so as to form at least two
ducts which extend substantially vertically above and
communicate at their lower ends with said at least one
laterally extending, linear opening; the ducts being
interconnected so as to allow air external to the
chamber to be continuously drawn into a first of said
ducts through said at least one laterally extending
linear opening, circulated through the ducts to a second
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3a
of said ducts and returned external to the chamber from
said second duct through said at least one laterally
extending linear opening;
(c) a first substantially planar, serpentine,
electrical heating element having an upper, heat-
generating, portion extending into the one of said ducts
and a lower, connecting portion, extending out of the
storage chamber through said at least one linear
opening; the upper portion of the heating element having
an uppermost portion having substantially parallel
upper right and an upper left sides and a lowermost
portion having substantially parallel lower right and a
lower left sides wherein the uppermost portion is angled
with respect to the lowermost portion within the plane
defined by the element so as to cause the right and left
sides of the lowermost portion to extend at an obtuse
angle of less than 180 with respect to the
corresponding right and left sides of the uppermost
portion; such angling of the heating element
facilitating insertion and removal of the heating
element through said at least one linear opening with
minimal clearance;
(d) a means for circulating air from a space to be
heated through the ducts;
(e) a heat-load control means for measuring the
temperature in the storage chamber; the heat load
control means generating a primary signal in response to
the temperature in the storage chamber falling below a
predetermined minimum and generating a secondary signal
in response to the temperature in the storage chamber
rising above a predetermined maximum; the heat-load
control means being electrically coupled to the heating
element such that the heating element is operative for
the generation of heat only when the heat-load control
means is generating the primary signal.
An electric thermal storage heating unit,
comprising:
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.
3b
(a) an insulated housing having a bottom wall with
at least a pair of laterally extending, linear openings;
the housing defining a storage chamber;
(b) a plurality of heat sink bricks configured
within the storage chamber so as to form at least two
pair of ducts which extend substantially vertically
above and communicate at their lower ends with the pair
of laterally extending, linear openings; the pair of
ducts being interconnected so as to allow air external
to the chamber to be continuously drawn into one of the
pair of ducts through one of the pair of laterally
extending linear openings, circulated from the first
duct to the other of the pair of ducts and returned
external to the chamber through the other of the pair of
laterally extending linear openings;
(c) a substantially planar, serpentine, electrical
heating element having an upper, heat-generating,
portion extending into one of the pair of ducts and a
lower, connecting portion extending out of the storage
chamber through open of the pair of linear openings; the
upper portion of the heating element having an uppermost
portion having substantially parallel upper right and an
upper left sides and a lowermost portion having
substantiall~ parallel lower right and lower left sides
wherein the uppermost portion is angled with respect to
the lowermost portion within the plane defined by the
element so as to cause the right and left sides of the
lower most portion to extend at an obtuse angle of less
than 180 with respect to the corresponding right and
left sides of the uppermost portion; such angling of the
heating element facilitating insertion and removal of
the heating element through said at least one linear
opening with minimal clearance;
(d) a~means for circulating air from a space to be
heated through the ducts;
(e) a heat-load control means for measuring the
temperature in the storage chamber; the heat load
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3c
control means generating a primary signal in response
to the temperature in the storage chamber falling below
a predetermined minimum and generating a second signal
in response to the temperature in the storage chamber
rising above a predetermined maximum; the heat-load
control means being electrically coupled to the heating
element such that the heating element is operative for
the generation of heat only when the heat-load control
means is generating the primary signal.
10Description of the Drawings
FIGURE 1 is a perspective view of one embodiment of
the ETS heating unit with portions thereof remove~.
FIGURE 2 is a side view of the ETS heating unit of
Fig. 1 with portions thereof removed.
15FIGURE 3 is a perspective view of two coupled
heating elements from the ETS heating unit of Fig. 1.
FIGURE ~ is a front view of the two heating
elements of Fig. 3.
FIGURE 5 is a perspective view of a heat-sink brick
from the ETS heating unit of Fig. 1.
FIGURE 6 is an electrical schematic diagram of the
electrical system for controlling the circulation of air
through the ETS heating unit.
FIGURE 7 is an electrical schematic diagram of the
electrical system for controlling the generation of heat
359
by the ETS heating unit.
Detailed Description of the Invention
Includinq a Best Mode
The electric thermal storage (ETS) space heating unit
S 10 converts electricity to heat which can be either
immediately employed for space heating or stored within
the heating unit until needed.
The ETS heating unit 10 includes an insulated housing
20 having a top 20a, a front 20b, a back 20c, a right side
(not shown), a left side 20e, and a bottom 20f. The
bottom 20f of housing 20 has at least one, preferably two,
parallel, lateral linear openings 21 extending from the
right side (not shown) to the left side 20e of housing 20.
Housing 20 defines a storage chamber 2S within which the
heat generated hy the unit 10 is created and stored.
A plurality of substantially rectangular, heat-sink
bricks 30 are configured within storage chamber 25 so as
to form vertical ducts 4Oa which extend substantially
vertically above the lateral linear openings 21 and
horizontal duct 40b which connect to vertical ducts 40a
at the top. Air may then circulate through the storage
chamber 25 by flowing up one vertical duct 4Oa, across
horizontal ducts 40b and down another vertical duct 40a.
The ducts 40 are preferably formed by substantially linear
channels 31 which extend along the entire length of a
first eide 30a of each brick 30. To form vertiaal ducts
40a bricks 30 are configured flrst side 30a to first side
30a such that the channels 31 extend in the same direction
and each channel 31 forms one-half of the vertical duct
40a.
A substantially planar, serpentine electrical heating
element 50 iB placed within at least one and preferably
all vertical ducte 40a. The heating elements 50 have an
upper, heat-generating portion 51 extending into the
vertical ducts 40a and a lower, connecting portion 52
extending out of storage chamber 25 through linear
openings 21. The upper portion 51 of each heating element
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50 lies within substantially the same plane as the linear
opening 21 through which it extends, such that the heating
element 50 may be inserted into and removed from the
storage chamber 25 through the linear opening 21 without
disturbing the bricks 30 or the housing 20.
The heating elements 50 are preferably angled to one
side along the plane defined by the upper portion 51 of
the heating element 50 and the linear opening 21 through
which the heating element 50 passes, so as to aid in
removing and inserting the heating elements 50 with
minimal clearance.
Referring specifically to Figs. 1 and 2: preferably,
the housing 20 has two, substantially parallel, linear,
lateral openings 21; a front opening 21a and a back
opening 21b and integrally paired heating elements 50: a
~ront element 50a, and a back element 50b, connected such
that they must be removed from and inserted into the
storage chamber 25 as a single unit.
The vertical ducts 40a and upper portion 51 of heating
elements 50 are sized and configured such that the heating
elements 50 may occupy the vertical ducts 40a without
significantly impeding air flow through the ducts 40.
The heating elements 50 are electrically
interconnected by any suitable means and can designed to
receive electrical current from any typical source of
electricity. Preferably the unit 10 is hard wired.
Referring generally to Fig. 7, the heating elements
50 are electrically coupled to a heat-load control means
60 which measures the temperature in the storage chamber
25 and generates a signal in relation to the temperature
in the storage chamber 25. The heat-load means 60
generates a primary signal after the temperature in the
storage chamber 25 falls below a predetermined minimum and
generates a secondary signal after the temperature in the
storage chamber 25 rises above a predetermined maximum.
The heat-load control means 60 allows electricity to flow
to the heating elements 50 when the primary signal is
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being generated and prevents the flow of electricity to
the heating elements 50 when the secondary signal is being
generated. Accordingly, the heating elements 50 receive
electricity and generate heat when the temperature within
the storage chamber 25 falls below the predetermined
minimum and prevents heating elements 50 from receiving
electricity and generating heat when the temperature
within the storage chamber 25 rises above the
predetermined maximum so as to prevent the heating unit 10
from overheating.
The minimum and maximum temperatures of the heat-load
control means 60 can be varied so as to allow the amount
of heat stored in the heating unit 10 to be varied based
upon demand.
A fan 70 circulates cool air from the space to be
heated, through the ducts 40 and back out into the space
to be heated.
Referring generally to Fig. 6, operation of fan 70 is
controlled by a temperature control means 80 such as a
thermostat which measures the temperature of the space to
be heated and operates the fan 70 in relation to that
temperature. The temperature control means 80 generates
a first signal after the temperature of the space to be
heated falls below a predetermined minimum and generates
a second signal after the temperature of the 6pace to be
heated rises above a predetermined maximum. The
temperature control means 80 allows electricity to reach
fan 70 when the temperature of the space to be heated
falls below the predetermined maximum and prevents
electricity from reaching fan 70 when the temperature in
the space to be heated rises above the predetermined
minimum.
In the preferred embodiment, the heating unit
optionally further comprises a timing control means 90,
electrically coupled to the heating element 50, for
preventing the flow of electricity to the heating element
50 during predetermined time periods. One of the main
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advantages achieved by use of an ETS heating unit is
that it allows heat to be generated and stored when the
cost of electricity is low, and then allows the low cost
stored heat to be used when the cost of electricity is
high. Accordingly, it is preferred to employ a timing
control means 90 to prevent the flow of electricity to
the heating element 50, regardless of any other signal
being generated, when the cost of electricity is high.
The heating unit 10 may be constructed to virtually
any desired size and heat capacity. However, for typical
uses including the space heating of homes, offices, work
shops, etc., heating units having a storage chamber 25
of about 0.1 to 0.3 cubic meters and a capacity to store
about 5,000 to 40,000 Kcal of heat are generally
suitable.
If desired, the heat-load control means 60
predetermined minimum and predetermined maximum may be
established by a remote thermostat 100 for measuring the
temperature of the environment external to the space to
be heated. The remote thermostat 100 then generates a
signal in relation to the temperature of the external
environment and establishes a predetermined minimum
and/or predetermined maximum in inverse relation to the
external temperature.
The heat sink bricks 30 employed in the heating
unit 10 are ~referably all substantially identical.
This reduces the cost of construction as only a single
configuration of brick 30 need be manufactured and
employed. Preferably, the heat sink bricks 30 are sized
to retain about 1,000 to 1,500 Xcals per brick 30.
Preferred materials for use as insulation 22
include MICROTHERM,TM a fumed amorphous silica
insulating material available from Micropore Insulation
Limited, TR-l9,TM a vermiculite based block insulation
material available from Thermic Refractories, Inc., CERA
BLANKET,TM a needled ceramic fiber insulating material
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available from Manville, CERA BOARD,TM an inorganic
bound insulating board material also available from
Manville and a calcium silicate insulation block
material also available from Manville.
Preferably, housing 20 can be constructed of steel
or aluminized steel; the heat sink bricks 30 can be
ceramic magnetite or olivine; and heating elements 50
can be tubular Nichrome or Incoloy.
The temperature control means 80 and heat-load
control means 60 may be any of the well known electrical
temperature sensors and controls including the mercury
switch, bi-metal thermometers typically employed in such
systems.
The specification is presented to aid in a complete
non-limiting understanding of our invention. Since many
variations and embodiments of the invention can be made
without departing from the spirit and scope of the
invention, the invention resides in the claims
hereinafter appended.
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