Note: Descriptions are shown in the official language in which they were submitted.
1 2~ 7~
Background of the Invention
The i~vention relates to a wall structur~ for
use in buildi~gs, preferably as walls in electricall~
heated one-family houses and the li~e, the wall struc-
ture bein~ made o~ a mate~ial of good heat storing
properties, an~ an electric heating elemen-t with an
electric resistor bein~ installed within the wall
ma-terial for heating the wall material. The invention
rela-tes mainly to internal walls used in buildings but
it is also applicable to external walls, in which case
the wall structure according to the invention requires
insulation on its outwardly facing surface.
In houses with electric heating, it is usually
~; difficult to distribute heat evenly within the rooms.
~'~ This is partly due to the fact that elect~ic hea-ting
elernents or radiators are relatively small in size so
that they have to be efficient to provide adequate
2 20 heating. Heat is thus distributed into -the rooms from
spot-like sources of heat. Large electric radiators
'A~ are not used widely as they are expensive, difficult.' to install, and possibly unaesthetic in appearance.
'' Electric radiators are often so efficient that they
heat up the dust and other dirt ga-thered upon them so
that unpleasant smell "spreads into the rooms. These
problems are further aggravated by the fact that
current is supplied to electric radiators in elec-
trically heated houses periodically, which is prefer-
ably done in the night-time due to the lower price of
night current.
The prior art includes various electrically
heated structural elements for heating buildings which
act as heat storing means. Such structuIal elements
may form part of a wall or floor structure. One wall
2 ~9~2~
heatincJ s~stem is disclosed in Finnish Pat~nt Speci-
fication 81~39. German Offenlegung~schrift 3300891
-teaches tha-t the wall or floor structure may comprise
a plurality of interconnected plate-like heating
ele~ents within which heatLng wires are inserted. A
common feature of all -these prior art solutions is
that the heat-storing elements with associated elec-
tric resistors are either complicated ln structure or
the heating of the elernents does not take place even-
ly. In the last-mentioned case, the electric resistors
and thei.r immediate environment may hea-t up locally to
a high -temperature as the heat is not conducted into
the surrounding stone material sufficiently rapidly.
Due to uneven heating the heat storing elements cannot
be charged e~ficiently and rapidly by heat eneryy. In
addition, uneven heating causes twisting and distor-
tion due to the thermal expansion of structures~
Further, heat resistors are deteriorated by over-
heating.
The object of the present invention is to
provide a new heating system which avoids the above-
mentioned drawbacks.
Summary of the Invention
According to the present invention, a wall
structure is provided in which a metallic, plate-like,
elonga-ted heat emission surface of high thermal
conductivity is attached to the electric resistor, the
heat emission surface being substantially larger in
area than the electric resistor and being arranged to
give off supplied heat into the wall material. The
heat storing material is preferably soapstone as it
has an excellent heat capacity and is relatively easy
to machine. The heat emission surface is preferably
positioned centrally within the soapstone elements so
that the so~pstone heats up very evenly. Pre~erred
embodiments of the wall structure acco~ding to the
inventlon are disclosed :Ln the accompan~ing claims 2
to 7.
One advantage of the wall structure according to
the invention is that, i required, it heats up very
rapidly and is nevertheless simple in structure. An-
other advantage is that it heats up evenly and the
service li~e of the electric resistors is long
although the resistors are not made of any extremely
expensive special alloys. Still another advantage ls
that the wall structure allows efficient utilization
of inexpensive night current without any disadvan-
. tages. The wall struc-ture, which has been heated up
during the night to a uniform temperature, thus
,~ containing a great amount of heat energy, supplies
heat into the room during several hours in the
~ daytime. The heating system according to the invention
.. may replace conventional electric radia-tors entirely
.; 20 or a-t least partly, in addition -to which it is
aesthetic in appearance
~,
Brief Description of the Drawings
In the following the invention will be described
in more detail by means of a preferred embodiment with
reference to the attached drawings, in which
Figure l is a schematic view of two wall struc-
. tures perpendicular to each other;
Figure 2 is a sectional view along the line II
- 30 II shown in Figure l;
Figure 3 shows a junction between two elements
in the wall structure without an electric heating
element;
Figure 4 shows the junction shown in Figure 3
~; 35 with the electric heating element in position;
~:iy~lre 5 19 an end view o~ the electric heatin~
element;
Figure 6 is a view o* the interface indicated by
the line~ VI-VI i.~ Figure 3;
Flgure 7 is a side view of the electrlc heating
element; and
Figure ~ illustrates the interconnection o~ two
electric heating elements.
Description of a Preferred Embodiment
Figure 1 shows a wall structure 1 perpendicl1lar
to a wall structure 2. Only the end of the wall struc-
ture 2 is visible. As appears from the figure, the
wall structures 1, 2 comprise a pluralit~ o~ elements
3, 4 indicated by broken lines. The elements are posi-
tloned side by side and piled on top of each other so
as to overlap each other. The elements in -the wall are
of two different standard sizes with the e~ception of
the uppermost elements 4, 4' which are lower than the
other elements 3, 3'. The elements 3, 3' are 300 mm in
height, 60 mm in thickness and from one metre up to
several metres in length. The elements 3, 3', 4, 4'
are made of soapstone or other similar material of
good heat storing properties. ~he heat capacity of the
material is important as the wall structure is
intended to store a great amount of heat energy.
Figure 2 shows the wall structure in a section
along the line II-II shown in Figure 1. It is to be
seen that an electric heating element 5 is provided at
the interfaces between the stone elements 3, 4. In
Flgure 2, the heating element is shown from the end.
Grooves extending longitudinally of the stone elements
3, 4 from end to end are provided in the stone ele-
ments 3, ~ for the electric heating elements 5. Ele-
ment end portions which remain visible are finished so
that the grooves canno-t be seen. The electric heating
element 5 is thus positioned within the wall structure
appropriately in vlew of the electric sa~ety regula-
tions. The electric heating elements 5 are positioned
centrally wlthin the wall structure in order to heat
up the wall evenly.
Figure 3 is an enlarged view of the hori~ontal
seam of two stone elements 3. The interface is
indicated by the re~erence numeral 17. The electric
heating element is not shown i.n the figure in order to
rnake the groove 6 machined for it clearly visible. An
expansion groove 7 intended for receiviny the housing
(part 8 in Figure 5) of the electric heating elernent 5
and supporting the electric heating element from below
ad~oins the groove 6. Accordingly, the electric heat~
ing element can be installed in the groove 6 without
any separate fastening means. As the grooves 6 are
formed in the edge surfaces of the stone elements 3, 4
as described above, the wall structure with associated
electric resistor elements can be erected rapidly.
Figure 4 corresponds to Figure 3 except that the
electric heating element 5 is installed in position.
It is to be seen that the electric heating element 5
is fitted in the grooves 6 and 7 with a small clear-
ance; and that the k~eating element is in parallel with
the stone element. The clearance is small, about l to
2 mm, in order that the electric heating elements
would be able to efficiently transfer heat energy into
the surrounding stone material. On the other hand, the
clearance cannot be too small as the electric heating
elements 5 have to be allowed to expand and contract
freely as determined by temperature changes. (The
thermal expansion of the heating elements 5 does not
correspond to that of the soapstone.)
In Figures 3 and 4, a cable conduit 9 is
2 ~ ~
indicated with a broken line. Electric cables for
in-terconnec-ting the electrlc heating elements 5 within
the wall structure run within the cable conduit.
Figure 6, which is a top vlew of the junction o~ two
stone eJ.ements 3, shows how the cable condui-t is
formed in a vertical interface lO between the stone
elements. Preferably, -the cable condui.t is .formed by
m-llling. Alternatively, the cable conduit may be
formed by drilling, in which case it need not follow
the interface between the stone elements but i-t can be
arranged to run e.g. centrally in the stone element.
For the ease of wiri.ng, it is, however, preferable to
position the cable conduit at -the interface between
~ two elements.
: 15 Figures 5 and 7 show the electric heating
. element 5 from the end and from the side on different
scales. It is to be seen that the electric heating
element has an electric resistor 12 comprising a pipe
extending around it, the resistor being attached by
- 20 soldering to a plate-like heat emission surface 13 of
high thermal conductivity by means of -the pipe ll. The
electric resistor 12, which is of the conventional
type, comprises at both ends snap~fastening means 14
for interconnection to another electric resistor. The
fastening means are preferably of the known male-
: female type. The electric resistor 12 is enclosed by a
housing 8 which also acts as a support for the elec-
tric heating element 5 when the element is positioned
within the stone element 3. The housing 8 is attached
-to the plate 13 by screws 15.
As appears from Figure 7, transverse grooves 16
are provided in the longitudinal edges of the plate-
like surface 13 to allow for thermal expansion and to
prevent the formation of thermal expansion stresses.
As shown in Figure 8, the electric heating
~9i72~
elements ~ are interconllec-ted by a connec-tion chute
section 17 following the cross-sectional shape of the
housing 8 around the electr~c resistor 12. The purpose
of the connection chute section 17 ls to protect the
interconnections during the installation of the elec-
tric heating elements.
Electric power may be supplied to the wall
structure according to the invention in different
ways, i.e. according to different heating programs,
depending on the type of the huilding in which the
wall structure is used and the preerences of the
occupants of the building.
The inve.ntion has been described above only by
means of one preferred embodiment, and it is therefore
to be mentioned that the invention can be embodied in
many ways within the scope of the attached claims.
Accordingly, it is possible in principle that the wall
structure comprises a single large heat storing block.
~ This solution is, however, essentially inferior to a
; 20 solution in which the wall structure comprises a
plurality of heat storing elements as several elements
allow the wall structure to be easily and rapidly
adapted to different surroundings. For this reason, it
is highly recommendable that at least two elements are
~ 25 used. The heat emission surface of the electric heat-
`~ ing elements may differ in geometry from that shown in
the figures. It is important, however, that the heat
emission surface is large, that is, substantially
larger than the surface area of the electric resistor.
Surface-installation of the electric heating elements
in the heat-storing material would also be possible,
; provided that such an installation would ensure proper
protection of -the heating elements so as to prevent
accidents. In addition, the transfer of heat into the
; 35 wall material would not take place as evenly as in a
213~ 1206
wall struc,tlJre ~it;hi.n ~lhich -the heatil-cJ elenlents are
installecl. From the aesthetic point of the view,
surface-installation is not yenerally -to be preferred.
Of course, it is possible to install -the electric
heating elements in vertical grooves insteacl of
horizontal grooves.
