Space heater with element supports

A heating apparatus for an enclosure including at least a ceiling and a side wall, the apparatus includes a plurality of electrical resistance heating wires or sections of electrical resistance heating wire, and support means therefor. The support means include support members each having a first part adapted to be secured relative to the ceiling or side wall and a second part which projects inwardly of the enclosure, the second part including a plurality of spaced apart heating wire support formations. The support members and the heating wire support formations are arranged such that in use substantial portions of the length of each of the plurality of the heating wires or sections of heating wire, are supported side by side by the support members each parallel to or generally parallel to each other and to the ceiling or side wall of the enclosure.

BACKGROUND TO THE INVENTION 
The invention relates to a heating apparatus for an enclosure having at 
least a ceiling and a side wall, apparatus comprising an electric heating 
element and support means therefor, and in particular although not 
exclusively, such a heating apparatus for a kiln for firing ceramics. 
Many forms of heating apparatus for use in enclosures such as kilns and 
furnaces are known. All of these prior all forms of heating apparatus 
suffer from disadvantages of one kind or other. 
In general heating enclosures such as kilns are provided with a plurality 
of heating apparatus. Each heating apparatus preferably forms a separate 
electrical circuit, such that if one fails the effect on the firing of the 
kiln is not too great, but several may be incorporated in one electric 
circuit. Hence, it is not desirable for the electrical elements used to 
have too large a cross sectional area as that limits the number which can 
be used. 
One form of prior art heating apparatus comprises strip or ribbon heating 
elements. On the walls of enclosures these may simply be hung over support 
means of various kinds protruding from the ceiling and/or wall, and in 
general hang down between successive support means. On the ceiling of the 
enclosure they may be wound around two spaced apart lines of support 
means, protruding from the ceiling, in a zig-zag formation parallel to the 
ceiling, or draped over support means suspended from the ceiling, and in 
general hang down between successive support means in a similar fashion to 
the walls. On the floor of an enclosure they may simply be laid in a zig 
zag fashion in troughs provided in the floor. However, strip or ribbon 
heating elements have a relatively large cross sectional area and 
therefore only a relatively small number of circuits can be provided. 
An alternative form of prior all heating apparatus provides rod elements, 
which may be supported in the same ways as the strip or ribbon elements 
previously described. These suffer from the same disadvantages as the 
strip or ribbon elements. 
Many prior art heating apparatus comprise heating elements in the form of 
wire spirals or coils. These may be supported in channels provided in the 
walls, ceiling or floor of the enclosure, or on trays supported from the 
appropriate surface of the enclosure. Such heating elements suffer from 
the disadvantage that as they under go heating and cooling cycles they 
migrate towards cold areas of the enclosure, for example towards the 
enclosure door. This results in an uneven distribution of the coil loops 
along the length of the coils. This in turn produces a number of 
deleterious effects. First, some parts of the enclosure are heated to a 
higher temperature than others resulting in uneven firing. Second, where 
the loops of the coil are so tightly bunched as to approximate to a tube 
the heat transfer is poor, which produces generally inefficient heating 
thus requiring greater power input, and shortening heating element life as 
they may reach higher temperatures than they are designed to withstand. 
Third, where such elements are supported on trays these often suffer from 
an excess of heat and start to warp thus requiring replacement. 
Wire spirals or coils may also be provided in free radiating form, that is, 
wound around supporting rods which are themselves supported from the 
appropriate surface of the enclosure. These elements suffer from the same 
kinds of disadvantages. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide an improved form of heating 
apparatus for an enclosure. 
According to a first aspect of the invention there is provided a heating 
apparatus for an enclosure comprising at least a ceiling and a side wall, 
the apparatus comprising a plurality of electrical resistance heating 
wires or sections of electrical resistance heating wire, and support means 
therefor, the support means comprising support members each having a first 
part adapted to be secured relative to the ceiling or side wall and a 
second part which projects inwardly of the enclosure, the second part 
comprising a plurality of spaced apart heating wire support formations, 
the support members and the heating wire support formations being arranged 
such that in use substantial portions of the length of each of the 
plurality of the heating wires or sections of heating wire, are supported 
side by side by the support members each parallel to or generally parallel 
to each other and to the ceiling or side wall of the enclosure. 
The invention provides the advantage that the problem of migration towards 
cool areas of the enclosure is greatly reduced. 
The lengths of each of the plurality of heating wires or sections of 
heating wire may preferably hang down between successive support members, 
and the support means further comprises spacer members each comprising a 
plurality of spaced apart heating wire separation formations, the spacer 
members and the heating wire separation formations being arranged such 
that in use each spacer member is located on the plurality of heating 
wires or sections of heating wire between successive support members to 
maintain the heating wires or sections of heating wire parallel to or 
generally parallel to each other. 
The spaced apart heating wire support formations may comprise spaced apart 
substantially parallel indentations in an upper surface of the second part 
of each support member. 
The heating wire separation formations may comprise spaced apart 
substantially parallel indentations in a lower surface of each spacer 
member. 
Preferably the spacer members are not secured relative to the ceiling or 
side wall of the enclosure. 
The plurality of electrical resistance heating wires or sections of 
electrical resistance heating wire preferably comprises a single wire 
arranged to provide a plurality of sections. 
The ceiling and at least one side wall may be lined with ceramic fibre with 
engagement means provided within the fibre, and the first parts of the 
support members may comprise one or more hook formations adapted to engage 
with the engagement means. The engagement means may comprise elongate 
members lying parallel or generally parallel to the ceiling or side wall. 
In an alternative where the ceiling and at least one side wall are lined 
with ceramic fibre and clad with metal sheet, and engagement means may be 
provided on the inner face of the metal sheet adapted to engage with the 
first parts of the support members. The engagement means may comprise 
sockets and the first parts of the support members may comprise elongate 
elements which are adapted to be received in the sockets. Alternatively, 
the engagement means may comprise protruding elements and the first parts 
of the support members may comprise bores adapted to locate on the 
protruding elements. The protruding elements may extend through the wall 
and into the enclosure. 
The ceiling and at least one side wall may be lined with brick, and bores 
may be provided in the brick for receipt of the first pails of the support 
members. 
According to a second aspect of the invention, there is provided an 
enclosure comprising at least a ceiling and a side wall, and at least one 
heating apparatus according to the first aspect of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 to 3, a heating apparatus 10 comprises support means 
in the form of a support member 11 and a spacer member 12, and a heating 
element 13 in the form of a wire. The heating apparatus 10 is provided for 
an enclosure having at least a wall and a ceiling, a part of the at least 
one wall 14 being shown in section in FIGS. 1 and 3. In this embodiment 
the wall is constructed from ceramic fibre. The support member 11 
comprises a first part 11a adapted to be secured to the wall 14, and is 
secured thereto as described below, and a second part 11b which projects 
inwardly of the enclosure. 
Engagement means in the form of upper and lower ceramic tubes 15, 16 are 
provided within the wall 14. The first part 11a of the support member 11 
comprises a book portion 17 which engages around the upper tube 15, and a 
bearing portion 18 which rests against or bears on the lower tube 16. 
The second part 11b of the support member 11 comprises a plurality of 
spaced apart heating wire support formations, in this case four 
indentations 19a to 19d, in its upper surface for receipt of the heating 
element 13. The spacer member 12 comprises a plurality of heating wire 
spacer formations, in this case four indentations 20a to 20d for receipt 
of the heating element 13. Both the support member 11 and spacer member 12 
are formed from electrically insulating material, typically cordierite 
which is a ceramic material with low iron content and low thermal 
expansion. 
The heating element 13 is formed of a single piece of electrical resistance 
heating wire of known kind, for example, nickel chromium alloy or ferrous 
chromium aluminium alloy. The heating element 13 is arranged to have a 
plurality of sections, in this embodiment four sections 13a to 13d which 
extend along substantially parallel paths, as shown in FIG. 3. In general 
there will be an even number of sections for ease of electrical 
connection. 
The heating element 13 is supported by a number, in this case seven, of 
support members 11 with the respective sections 13a to 13d of the heating 
element 13 received within respective indentations 19a to 19d in each 
support member 11. Between successive support members 11, the heating 
element 13 hangs downwards forming loops as shown in FIG. 1. A spacer 
member 12 is located on the heating element 13 between each pair of 
support members 12, with the respective sections 13a to 13b of the heating 
element 13 received within respective indentations 20a to 20d of the 
spacer member 12. The spacer member 12 simply selves to maintain the 
separation between the different sections 13a to 13b of the heating 
element 13. 
The heating apparatus 10 thus described provides the advantage that the 
electrical element 13 cannot migrate towards the cooler areas of the 
enclosure to the same extent. The heating element 13 will contract when it 
cools, but this will result principally in a change in shape of the loops 
of the element 13 between successive support members 11, which has little 
effect on their performance. Hence, heating apparatus 10 according to the 
invention do not suffer from the same problems of uneven heat distribution 
and thus inefficient heating of the enclosure, nor do they suffer from the 
disadvantage of shortened element life, to the same extent. 
Referring now to FIG. 4, an embodiment of a heating apparatus 24 according 
to the invention suitable for use on the ceiling of a ceramic fibre lined 
enclosure is illustrated, with like parts being like referenced. An 
enclosure ceiling 25 has engagement means in the form of pairs of ceramic 
tubes 26, 27 driven through it, and a first part 28a of a support member 
28 comprises pairs of hook portions 29, 30, which engage with the tubes 
26,27 to secure the support member 28 in place. A second part 28b of the 
support member 28 provides formations 19 as previously described, in this 
case two sets, for the receipt of two heating elements 13. 
Referring now to FIG. 5, a further adaptation of the invention for the 
provision of heating elements 13 to the floor of an enclosure, or to a 
kiln car is illustrated, with like parts being like referenced. An 
enclosure 34, comprises upstanding portions 35 which provide shoulders on 
which support members 36 rest. The upstanding portions also support the 
load within the enclosure for firing. The support members 36 provide sets 
of formations 19 as previously described, each set of formations for 
receipt of a respective heating element 13. 
Referring now to FIGS. 6 to 9, further embodiments of support members 
according to the invention are illustrated. The support members of FIGS. 6 
to 8 are appropriate for use in ceramic fibre lined enclosures whilst the 
embodiment of FIG. 9 is appropriate for use in a brick lined enclosure. 
Referring in particular to FIG. 6, a ceramic fibre wall 14 is supported 
from a metal case 40, to the inner face of which an engagement means in 
the form of a socket 41 is fixed by welding. A support member 42 comprises 
a first part 42a, in the form of a heat resistant rod, which passes 
through the ceramic fibre wall 14 and locates in the socket 41, and a 
second part 42b in the form of a ceramic bobbin, mounted on the rod and 
providing the appropriate formations 19. 
Referring in particular to FIG. 7, the ceramic fibre wall 14 is again 
supported from a metal case 40 and an engagement means in the form of a 
threaded stud 44 is attached to the inner face by welding. A support 
member 45 comprises a first part 45a, in the form of a ceramic tube which 
penetrates through the ceramic fibre wall 14 and locates on the threaded 
stud 44 and a second part 45b, in the form of a ceramic bobbin mounted on 
the tube, which provides the required formations 19 for receipt of the 
heating element 13. 
Referring now in particular to FIG. 8, the ceramic fibre wall 14 is again 
supported from a metal case 40 to the inner face of which an engagement 
means in the form of a locating rod 49 is attached by welding. The 
locating rod 49 is of sufficient length that it penetrates completely 
through the ceramic fibre wall 14 into the enclosure . A ceramic support 
member 50 comprises a first part 50a which penetrates into the wall 14 and 
locates on the rod 49, by means of a bore 51. A second part 50b of support 
member 50 provides the required formations 19 for receipt of the heating 
element 13, and comprises a washer portion which ensures the formations 19 
are spaced appropriately from the wall 14. 
Referring now to FIG. 9 in particular, a wall 55 of brick comprises an 
engagement means in the form of a bore 56. Support member 57 comprises a 
first part 57a in the form of an elongate portion which locates in the 
bore 56, and a second part 57b which extends into the enclosure and 
provides the required formations 19 for receipt of the heating element 13. 
Many other forms of support members may be provided within the scope of the 
invention. 
Referring now to FIGS. 10 to 12 a further embodiment of a heating apparatus 
60 according to the invention is illustrated, with like parts being like 
referenced. A fibre lined wall 14 is supported from a metal case 40. To 
the inner surface of the fibre wall 14 a sheet of cordierite 61 is 
adhered, the sheet 61 provides engagement means in the form of holes 62 
adjacent voids 63 in the fibre wall 14. Each support member 64, comprises 
a first part 64a shaped and adapted for engagement in hole 62 and void 63, 
and a second pail 64b which provides the formations 19. The support 
members 64 are engaged in the holes 62, as shown in FIG. 12, by rotation 
during insertion. 
For most heating enclosures, a plurality of such heating apparatus 10 are 
provided. In particular, it is beneficial to provide a plurality of 
separate heating elements each forming a separate electric circuit such 
that if one heating element fails the effect on the heating of the kiln as 
a whole is not so significant as to cause failure of the whole filing 
process. For example, if the heating enclosure uses a three phase 
electrical supply, it may be provided with a total of 18 circuits, six on 
each phase. 
The plurality of heating apparatus according to the invention are 
distributed appropriately around the enclosure to provide heating that is 
as even as possible. Thus, they may be separated by greater distances 
towards the top of the enclosure to aid temperature uniformity within the 
enclosure. 
The electrical elements described above comprise four sections running 
substantially parallel to each other and to the wall and/or the ceiling of 
the enclosure. Clearly, electrical elements with fewer or more sections 
may be used in embodiments of heating apparatus according to the 
invention, according to the particular circumstances. Indeed, the heating 
apparatus within a single enclosure may comprises elements with differing 
numbers of sections. In particular to aid temperature uniformity elements 
towards the top of the enclosure may comprise fewer sections than those 
towards the bottom of the enclosure. 
The features disclosed in the foregoing description the following claims or 
the accompanying drawings, expressed in their specific forms or in terms 
of a means for performing the disclosed function, or a method or process 
for attaining the disclosed result, or a class or group of substances or 
compositions, as appropriate, may, separately, or in any combination of 
such features, be utilised for realising the invention in diverse forms 
thereof.