CA1295359C - Electric thermal storage heating unit - Google Patents

Electric thermal storage heating unit

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Publication number
CA1295359C
CA1295359C CA000583417A CA583417A CA1295359C CA 1295359 C CA1295359 C CA 1295359C CA 000583417 A CA000583417 A CA 000583417A CA 583417 A CA583417 A CA 583417A CA 1295359 C CA1295359 C CA 1295359C
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CA
Canada
Prior art keywords
heat
ducts
storage chamber
heating element
unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
CA000583417A
Other languages
French (fr)
Inventor
Paul John Steffes
Brian Al Fosaaen
Thomas Peter Steffes
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STEFFES ETS Inc
Original Assignee
STEFFES ETS INC.
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Filing date
Publication date
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Publication of CA1295359C publication Critical patent/CA1295359C/en
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Abstract

Abstract of the Disclosure An electric thermal storage heating unit including an insulated housing defining a storage chamber having two lateral linear openings at the bottom; a plurality of heat-sink bricks within the storage chamber forming vertical ducts above the lateral linear openings; an electrical heating element having an upper portion extending into the ducts and a lower portion extending out of the storage chamber through a linear opening; a fan; a temperature control means for controlling operation of the fan in relation to the temperature of the space to be heated; and a heat load control means for measuring the temperature in the storage chamber and controlling the generation of heat in response thereto.
The upper portion of the electrical heating element lying within substantially the same plane as the linear opening such that the heating element may be inserted into and removed from the storage chamber through the linear opening without significantly disturbing the bricks or the housing.

Description

12~3~9 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 ~L2~3~3~

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 ~2~S359 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 j..~t ~

lZ9~359 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:

lZ~53~9 .
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 ~L2953~9 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 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 ~2~;3~9 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 ~ 25~3~9 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 12~;3~9 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 . ~,, 12~3~9 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.

; ~,

Claims (18)

1. 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 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.
2. An electric thermal storage heating unit, comprising:
(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 substantially 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 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.
3. The unit of Claim 1 wherein the air circulating means is electrically operable and the unit further comprises a temperature control means for measuring the temperature of the space to be heated by the unit; the temperature control means (i) generating a first signal in response to the temperature of the space to be heated falling below a predetermined minimum and generating a second signal in response to the temperature of the space to be heated rising above a predetermined maximum, and (ii) electrically coupled to the circulating means for rendering the circulating means operative for the circulation of air only in response to the temperature control means generating the first signal.
4. The unit of Claim 1 further comprising a timing control means, electrically coupled to the heating element, for preventing the flow of electricity to the heating element during predetermined time periods.
5. The unit of Claim 1 wherein the heat sink bricks configured within the storage chamber can retain up to about 40,000 Kcal.
6. The unit of Claim 1 wherein the housing is insulated to a thermal conductivity of less than about 150 cal/(hr) (m) (°C).
7. The unit of Claim 2 wherein said first and second linear openings are substantially parallel.
8. The unit of Claim 1 wherein the storage chamber has a volume of about 0.1 to 0.3 m3.
9. The unit of Claim 8 wherein all of the heat sink bricks are substantially identical and about 10 to 100 bricks are configured within the storage chamber.
10. The unit of Claim 9 wherein the bricks are substantially rectangular and have a substantially linear channel along the entire length of a first face thereof; the channels in the bricks forming the ducts.
11. The unit of Claim 7 wherein (i) bricks are substantially rectangular and have a substantially linear channel along the entire length of a first face thereof; the channel in the bricks forming the ducts, and (ii) the ducts extend substantially vertically from the laterally extending linear openings and are coupled at the top by a longitudinal duct connecting each vertical duct extending from one of the linear openings with the vertical duct extending from the other linear opening.
12. The unit of Claim 7 further comprising a second electrical heating element configured substantially identical to the first heating element with the first heating element extending into one of the pair of ducts through one of the pair of linear openings, the second heating element extending into the other of the pair of ducts through the other of the pair of linear openings, and the first and second heating elements coupled by a coupling element located outside the storage chamber.
13. The unit of Claim 3 wherein the temperature control means comprises a thermostat.
14. The unit of Claim 13 wherein the temperature control means predetermined minimum and predetermined maximum may be readily altered by a user of the unit.
15. The unit of Claim 1 wherein the air circulating means is a fan.
16. The unit of Claim 1 wherein the heat-load control means comprises a thermostat.
17. The unit of Claim 16 wherein the heat-load control means predetermined minimum and predetermined maximum are established manually by a user of the unit.
18. The unit of Claim 16 wherein the heat-load control means predetermined minimum and predetermined maximum are established by a remote thermostat for measuring the temperature of the environment external to the space to be heated; the remote thermostat generating a signal in relation to the temperature of the external environment and electrically coupled to the heat-load control means so as to establish the predetermined minimum and predetermined maximum in inverse relation to the external temperature.
CA000583417A 1987-11-24 1988-11-17 Electric thermal storage heating unit Expired - Lifetime CA1295359C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US12460087A 1987-11-24 1987-11-24
US124,600 1987-11-24

Publications (1)

Publication Number Publication Date
CA1295359C true CA1295359C (en) 1992-02-04

Family

ID=22415806

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000583417A Expired - Lifetime CA1295359C (en) 1987-11-24 1988-11-17 Electric thermal storage heating unit

Country Status (1)

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CA (1) CA1295359C (en)

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