JPH11257678A - Floor heating structure and its execution method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the installation work, etc., of a heating panel at an execution site. SOLUTION: In floor heating structure where a heating panel 3 having a heater consisting of an electric heating wire 9 is installed between small joists arranged at regular intervals on beams, a folded body constituted by folding a specified number of heating panels 3 compactly can be made by coupling the adjacent heating panels 3 with one another by flexible coupling members 10 longer than the width dimension of the small joist and in condition that they are separated by a distance longer than the two times of the board thickness of the heating panel 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floor heating structure in which a heating panel having a heating element is installed between small joists disposed at regular intervals on a discarded floor, and a construction method thereof.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Laid-Open No.
As shown in the official gazette, a floor configured to install a heating panel having a heating element composed of an electric heating wire or the like between small joists arranged at predetermined intervals on a stretch (rough floor). In the heating structure, the heating elements of the adjacent heating panels are connected to each other by electric wires, and the connecting electric wires are wired through grooves formed on the upper surface of the small joist.

[0003]

According to the floor heating structure described in the above-mentioned publication, the heating elements of a predetermined number of heating panels carried into the construction site are connected in advance by electric wires, so that There is an advantage that the wiring operation can be significantly simplified. On the other hand, after transporting the plurality of heating panels connected by the connection wires in an integrated state, the work of sequentially installing the heating panels between the small joists must be performed. The work is extremely complicated, and there is a problem that an excessive tensile force acts on the connection electric wire during the heating operation and the installation operation of the heating panel, so that disconnection easily occurs.

The present invention has been made in view of the above circumstances, and provides a floor heating structure and a construction method capable of easily performing a work of installing a heating panel at a construction site.

[0005]

The invention according to claim 1 is
In a floor heating structure in which a heating panel having a heating element is installed between small joists disposed at regular intervals on the floor, adjacent heating panels are longer than the width of the small joist and heated. In a state where they are separated by a distance longer than twice the thickness of the panel, they are connected to each other by a flexible connecting member.

[0006] According to the above configuration, the plurality of heating panels connected to each other by the connecting member are conveyed to the construction site in a state where they are alternately folded at the connecting portions, and then the respective heating panels are developed and discarded. By installing the heating panels, the respective heating panels are easily and properly installed between the small joists arranged at regular intervals on the waste.

According to a second aspect of the present invention, in the floor heating structure according to the first aspect, a heating element including an electric heating wire is provided on the heating panel, and the electric heating wires of the adjacent heating panels are connected to each other by an electric wire. It was done.

[0008] According to the above configuration, the electric heating wires provided on the adjacent heating panels are conveyed to the construction site in a state where they are connected to each other by the electric wire, and are separated from each other by the small joists arranged at regular intervals. After installing each heating panel, simply connect the electric wire derived from the specific heating panel to the power supply, it is possible to wire so that power can be supplied to the electric heating wire of each heating panel, Wiring work at the construction site will be simplified. In addition, since the adjacent heating panels are transported in a state where they are connected to each other by the connection member, it is possible to prevent a tensile force from acting on the connection wires during this transport, and to effectively prevent disconnection thereof. Will be.

According to a third aspect of the present invention, in the floor heating structure according to the second aspect, a notch serving as a housing portion for a connecting wire is formed in the wire lead-out portion of the heating panel, and a notch is formed on an upper surface of the small joist. This is one in which a groove for wiring is formed.

According to the above configuration, the heating panel is transported and installed in a state where the connecting wires led out from the wire outlet of the heating panel are accommodated in the notches for housing the wires. When the heating panel is installed, the electric wires are wired through the wiring grooves provided on the upper surface of the small joist, so that the electric wires are prevented from projecting to the upper surface of the small joist, and the adjacent heating is performed. The electrical heating wires of the panels will be connected to each other by the wires.

According to a fourth aspect of the present invention, in the floor heating structure according to any one of the first to third aspects, a heat dissipation sheet covering the upper surface and side surfaces of the heating panel and covering the upper surface and side surfaces of the small joist are provided. A heat radiation sheet is provided, and the heating panel is disposed on the side wall of the small joist in a state where the side panel of the heating panel is in contact with the heating panel.

According to the above construction, the small joists whose upper surfaces and the side surfaces are covered with the heat radiating sheet are disposed at regular intervals on a discard basis, and the upper surfaces and the side surfaces are covered with the heat radiating sheet between the small joists. By installing the heated heating panel, heat generated in the heating element of the heating panel is transmitted from the side surface of the heating panel to the side surface of the small joist, and the upper surface of the small joist via the heat dissipation sheet. It is transmitted to the part efficiently.

According to a fifth aspect of the present invention, there is provided a method of constructing a floor heating structure in which a heating panel having a heating element is installed between small joists disposed at regular intervals on a discarded basis. After connecting a plurality of heating panels by a connecting member having a length longer than the width of the small joist and sequentially separated by a distance longer than twice the plate thickness of the heating panel, the connecting portion by the connecting member A folding body of the heating panel is formed by folding each heating panel, and the heating panel located at the end of the folding body is inserted between the small joists arranged at one end on the discard side, and then The folding body of the heating panel is unfolded and sequentially inserted and installed between small joists.

According to the above configuration, after the small joists whose top and side surfaces are covered with the heat radiating sheet are disposed at regular intervals on a discarded basis, the folding members of the heating panel are unfolded and sequentially arranged between the small joists. By inserting, a floor heating structure is obtained in which heating panels are respectively installed between small joists arranged at regular intervals on a discarded basis.

According to a sixth aspect of the present invention, in the method of constructing a floor heating structure according to the fifth aspect, after the small joists whose upper surfaces and side surfaces are covered with the heat radiating sheet are disposed at regular intervals on a discarded basis, A heating panel having a heating element and having a top surface and a side surface covered with a heat radiating sheet is inserted between the small joists, and the heating panel is discarded with the side portions of the heating panel abutting against the side portions of the small joists. It is designed to be installed on top.

According to the above construction, after the small joists whose upper surfaces and the side surfaces are covered with the heat radiation sheet are disposed at regular intervals on a discard basis, the upper surfaces and the side surfaces are covered with the heat radiation sheet between the small joists. By installing the heating panel, the heat generated in the heating element of the heating panel is transmitted from the side portion of the heating panel to the side portion of the small joist, and the upper portion of the small joist via the heat dissipation sheet. Floor heating structure configured to be transmitted to the vehicle.

According to a seventh aspect of the present invention, there is provided a floor heating structure in which a heating panel having a heating element is installed between small joists disposed at regular intervals on a discarded basis. In addition to the installation of the small joists along the portion, a heat radiating sheet is provided to cover the top and side surfaces of the set including the heating panel and the small joists.

According to the above construction, the heating panel includes the heating element and the small joist installed on one side of the heating panel.
The heat generated in the heating element of the heating panel, the heat generated by the heating element of the heating panel, the heat radiation sheet from the upper surface portion of the heating panel by the set body covered with the heat radiation sheet on the top surface and the side surface are sequentially arranged on And transmitted to the upper surface of the small joist.

[0019]

1 and 2 show an embodiment of a floor heating structure according to the present invention. The floor heating structure includes a slab 1 constituting a rough floor, small joists 2 arranged at regular intervals on the slab 1, and a heating panel 3 installed between adjacent small joists 2 and 2. And a floor finishing material 4 installed so as to cover the small joists 2 and the upper surface of the heating panel 3, and a power supply 5 for supplying electric power for heating to the heating panel 3.

The small joist 2 has a length corresponding to the floor heating installation area on the discard 1 and is made of a wooden square or the like having a thickness corresponding to the thickness of the heating panel 3. Is, as shown in FIG.
A pair of front and rear wiring grooves 6, 6 having a depth corresponding to the wire diameter of 0 are formed. In addition, the small joist 2
A heat radiating sheet 7 that covers the upper surface and both left and right sides is provided. The heat radiating sheet 7 is made of a material having high thermal conductivity such as copper or aluminum, and is fixed to the upper surface and the left and right side surfaces of the small joist 2 with an adhesive or the like. In the heat radiation sheet 7, circular holes 8 are formed at predetermined intervals in a portion covering the upper surface of the small joist 2.

The heating panel 3 includes a heat insulating material layer 14 in which a heating element composed of an electric heating wire 9 such as a nichrome wire is embedded in a meandering state, and copper or aluminum covering the upper surface and side surfaces of the heat insulating material layer 14. And the like, and is configured to generate heat when power is supplied from the power supply 5 to the electric heating wire 9. The heat insulating material layer 14 is formed of a material having a lower rigidity than the small joist 2, for example, a foamed resin such as foamed polyester or urethane. Further, a lead-out portion of an electric wire 10 for supplying electric power to the electric heating wire 9 is provided at opposing corner portions of the heating panel 3.
A notch 11 in which the electric wire 10 is accommodated when the heating panel 3 is transported, which will be described later, is formed.

In order to construct the floor heating structure, a small joist 2 whose upper surface and side surfaces are covered with a heat radiating sheet 7
The heating panel 3 having the electric heating wire 9 and having the upper surface and the side surface covered with the heat dissipation sheet 15 is manufactured.
Thereafter, as shown in FIG. 4, the electric heating wires 9 of the adjacent heating panels 3 are connected to each other by electric wires 10, and the flexible connecting member 1 such as an adhesive tape or a string is used.
2, the adjacent heating panels 3 are sequentially connected in a state where they are separated by a distance longer than the width of the small joist 2 and longer than twice the thickness of the heating panel 3, and the required number of heating panels 3 are sequentially connected. The connecting body 3A of the heating panel 3 is formed. And FIG.
As shown in the figure, a folded body 3B of the heating panel 3 is formed by alternately folding the linked bodies 3A of the respective heating panels 3 at the connecting portion formed by the connecting members 12, and the number of folded bodies 3B of the heating panel 3 and the required number Convey small joists 2 etc. to the construction site.

Next, as shown in FIGS. 6 and 7, the small joists 2 are installed on the cut-off 1 at intervals corresponding to the width of the heating panel 3 at the construction site where the cut-off 1 is installed. Then, a line L is drawn, and the small joist 2 is fixed on the line L with a nail or an adhesive. Then, the heating panel 3 located at the end of the folding body 3B is discarded 1
After inserting the heating panel 3 between the small joists 2 and 2, after inserting the heating panel 3 between the small joists 2 and 2, the folding body 3B of the heating panel 3 is developed. By
As shown in FIG. 8, the heating panel 3 is installed over the entire floor heating installation area with the side surface of the heating panel 3 in contact with the heat dissipation sheet 7 covering the side surface of the small joist 2. When the heating panel 3 is installed, the electric wire 10 connecting the electric heating wires 9 of the adjacent heating panels 3 is wired on the wiring groove 6 formed on the upper surface of the small joist 2. I do.

Thereafter, as shown in FIG. 2, an electric wire 10 led out of a heating panel 3 provided at one end of the floor heating installation area and a heating wire provided at the other end of the area. The electric wire 10 led out of the panel 3 is connected to the power supply 5. In addition, if necessary, the connecting member 12 for connecting the adjacent heating panels 3 is removed, and after installing a particle board or a small joist around the floor heating installation area, a wooden flooring is provided so as to cover the entire floor surface. Timber,
A floor finishing material 4 made of a laminated material of carpet and plywood or a tatami mat is placed, and if necessary, small joists 2 are attached with an adhesive or the like.
The floor heating structure as shown in FIG.

When the floor finishing material 4 is adhered to the upper surface of the small joist 2, an adhesive is applied to the upper surface of the small joist 2 through a hole 8 formed in the heat radiation sheet 7. The finishing material 4 can be firmly fixed to the small joist 2. In order to effectively prevent the heat of the heating panel 3 from escaping to the lower part of the floor, it is desirable to provide a heat insulating material made of a foamable plastic material, a cork material, or the like on the lower surface of the waste 1.

As described above, in the floor heating structure in which the heating panel 3 having the heating element such as the electric heating wire 9 is installed between the small joists 2 and 2 arranged at regular intervals on the discard 1 With the adjacent heating panels 3 and 3 separated by a distance longer than the width of the small joist 2 and longer than twice the thickness of the heating panel 3, the connecting members 12 having flexibility are used. Since the plurality of heating panels 3 are alternately folded at the connecting portion by the connecting member 12, a predetermined number of heating panels 3 can be conveyed in a compactly folded state in a folded body 3 </ b> B. . Therefore, in a state where the heating panels 3 are prevented from being separated, the heating panels 3 can be easily transported to the construction site in an integrated state. The heating panel 3 can be easily installed at an appropriate position on the discard 1 by sequentially inserting the heating panel 3 between 2 and 2.

Further, as shown in the above embodiment, when the electric heating wires 9 of the adjacent heating panels 3 and 3 are transported to the construction site in a state where they are connected to each other in advance by the electric wires 10, After the installation of the heating panel 3, simply connect the electric wire 10 derived from the specific heating panel 3 located at both side ends and the like of the floor heating installation area to the power supply 5,
Since electric power can be supplied to the electric heating wire 9 of each heating panel 3, the wiring work at the construction site can be effectively simplified. Moreover, as described above, despite the configuration in which the electric heating wires 9 of the adjacent heating panels 3 and 3 are transported to the construction site in a state where the electric heating wires 9 are connected to each other in advance by the electric wire 10, the adjacent heating panels 3 and 3 are connected. 3 is connected by the connecting member 12 so that the heating panels 3 and 3 can be prevented from separating from each other. Therefore, when the heating panel 3 is transported, the connection electric wire 10 is pulled. Disconnection can be prevented.

In particular, as shown in the above embodiment, the notch 11 serving as a housing for the electric wire 10 is provided in the electric wire outlet of the heating panel 3.
Is formed, when the plurality of heating panels 3 are transported in a folded state, the electric wires 10 are accommodated in the cutouts 11 so that the electric wires 10 are interposed between the folded heating panels 3. It is possible to prevent occurrence of a situation in which the sheet is pinched and damaged.

Further, a groove 6 for wiring is formed on the upper surface of the small joist 2, and the electric wire 10 is positioned on the groove 6 to prevent the electric wire 10 from protruding from the upper surface of the small joist 2. In the case where the electric wire 10 is configured to be wired, when the floor finishing material 4 is installed, the electric wire 10 is prevented from being caught between the floor finishing material 4 and the small joist 2. Therefore, the damage can be surely prevented.

In the above embodiment, the heat radiation sheet 15 covering the upper and side surfaces of the heating panel 3 and the small joist 2
Since the heat radiation sheet 7 covering the upper surface and the side surface of the heating panel 3 is provided, and the side surface of the heating panel 3 is in contact with the side surface of the small joist 2, the heat radiation sheet 7 is disposed on the discard 1. After installing the small joist 2 and the heating panel 3, the entire floor heating installation area can be removed without the need for complicated work such as mounting the heat radiation sheet 7 so as to cover the upper surfaces of the small joist 2 and the heating panel 3. It can be heated evenly.

That is, the small joist 2 to which the heat radiating sheet 7 is attached so as to cover the upper surface and both right and left sides in the manufacturing factory is carried into the construction site, and is fixed on the above-mentioned disposal 1 at regular intervals. Thereafter, a simple work of installing and wiring the heating panel 3 whose upper surface and side surfaces are covered with the heat dissipation sheet 15 between the adjacent small joists 2 is performed, and the upper surface and the left and right side surfaces of the small joists 2 are performed. Is covered with the heat radiating sheet 7 and the floor heating structure in which the heating panel 3 is installed along the left and right sides is obtained.

The electric heating wire 9 of the heating panel 3
The heat generated by energizing the heating panel 3 is transmitted from the side surface of the heating panel 3 to the heat radiation sheet 7 covering the left and right sides of the small joist 2, and the heat is transmitted to the heat radiation sheet 7 covering the upper surface of the small joist 2. By doing so, it is possible to effectively raise the temperature of the installation portion of the small joist 2 without a heating element,
The entire floor heating installation area can be uniformly heated. Further, since the transportation and installation of the small joist 2 are performed in a state where the heat radiation sheet 7 is fixed to the upper surface and the left and right side surfaces of the small joist 2 in advance, the heat radiation sheet is transported when the small joist 2 is transported. 7 can be effectively prevented from being damaged.

It should be noted that, after the small joists 2 are arranged at regular intervals on the discards 1, the heating panel 3 is installed between the small joists 2 and 2, instead of the above-described embodiment, FIG. As shown, the small joist 2 is installed along one side of the heating panel 3, and the heat radiating sheet 7 that covers the upper surface and the side surface of the set body 13 including the heating panel 3 and the small joist 2 is provided. A plurality of sets 13 may be arranged on the above-mentioned distraction 1 in a state where the side portions covered with the heat radiation sheet 7 are in contact with each other.

In the case of such a configuration, the set members 13 are arranged and fixed on the discard 1 only, and the electric joists 2 and 2 arranged at regular intervals on the discard 1 are electrically connected. A heating panel 3 having a heating element such as a heating wire 9 is installed, and a floor heating structure including an assembly of a set 13 whose upper surface and side surfaces are covered with a heat dissipation sheet 7 can be easily obtained.

The electric heating wire 9 of the heating panel 3
As shown by an arrow α in FIG. 10, the heat generated by being energized is transmitted to the upper surface of the small joist 2 through the heat radiation sheet 7 covering the upper surface of the heating panel 3 and the adjacent set body As shown by the arrow β, the heat of 13a can be transmitted to the side surface of the heat radiation sheet 7 and from the side surface to the upper surface of the small joist 2. Therefore, also in the above-described embodiment, there is an advantage that the temperature of the installation portion of the small joist 2 having no heating element can be effectively increased, and the entire floor heating installation area can be uniformly heated.

As shown in FIG. 11, a radiating sheet 16 made of a flexible material is provided so as to cover the upper surfaces of the notches 11 formed in the corners of the adjacent heating panels 3 and 3. , And a structure in which a heat generating element made of an electric heating wire or the like is provided on the heat radiation sheet 16. With such a configuration, the connection electric wire 10 accommodated in the cutout 11 can be effectively protected by the heat dissipation sheet 16. In addition, the installation portion of the notch 11 can be effectively heated by the heat released from the heat radiation sheet 16 and a part of this heat is transmitted to the installation portion of the small joist 2 so as to heat the floor. There is an advantage that the entire installation area can be more effectively heated.

[0037]

As described above, according to the first and fifth aspects of the present invention, the adjacent heating panels are made longer than the width of the small joist and more than twice the thickness of the heating panel. In a state of being separated by a long distance, they are connected to each other by a flexible connecting member, and each heating panel is alternately folded at a connecting portion by this connecting member to form a folded body of the heating panel. After the heating panel located at the end is inserted between the small joists disposed at one end on the side of the distraction, the folded body of the heating panel is unfolded and sequentially inserted and installed between the small joists. Because of such a configuration, the work of transporting the folded body of the heating panel to the construction site,
The work of disposing each heating panel between small joists arranged at regular intervals on a discarded basis can be easily performed.

Further, the invention according to claim 2 is configured such that the electric heating wires of the adjacent heating panels are conveyed to the construction site in a state where they are connected to each other in advance by electric wires. By simply connecting the electric wires derived from the heating panels etc. located at both ends of the installation area to the power supply, it is possible to supply power to the electric heating wires of each heating panel respectively, making the wiring work at the construction site more It can be simplified effectively.

According to the third aspect of the present invention, a notch serving as an electric wire accommodating portion is formed in the electric wire lead-out portion of the heating panel, and a wiring groove is formed on the upper surface of the small joist. When the panel is transported in a folded state, for example, by storing the electric wire in the notch, the electric wire can be prevented from being caught and damaged between the folded heating panels, and the heating panel and the small joist can be prevented. When the floor finishing material is installed on the floor finishing material, there is an advantage that the electric wire can be reliably prevented from being caught and damaged between the floor finishing material and the small joist.

Further, in the invention according to claims 4 and 6, a heat radiation sheet covering the upper surface and side surfaces of the heating panel and a heat radiation sheet covering the upper surface and side surfaces of the joist are provided. After arranging the small joists whose side surfaces are covered at regular intervals on the ground, a heating panel having a heating element is installed between the small joists, and the heating panel is provided on a heat dissipation sheet covering the side surfaces of the small joists. Since the installation is performed in a state where the side parts of the abutment are in contact with each other, it is possible to omit complicated work such as installing a heat radiation sheet so as to cover the top of the joist and the heating panel at the construction site, and Damage to the heat radiation sheet and the like can be prevented. Then, after transmitting the heat of the heating panel from the side portion to the side portion of the small joist, by transmitting the heat to the upper portion of the small joist via the heat dissipation sheet, the installation portion of the small joist without a heating element is provided. Effectively raise the temperature,
This has the advantage that the entire floor heating installation area can be heated evenly.

According to a seventh aspect of the present invention, there is provided a floor heating structure in which a heating panel having a heating element is provided between small joists disposed at regular intervals on a discarded basis. Along with installing the small joists along the sides, and providing a heat dissipation sheet that covers the top and side surfaces of the set consisting of this heating panel and small joists, the above set only needs to be aligned and fixed. A heating panel having a heating element such as an electric heating wire is installed between the small joists disposed at regular intervals on the disposable, and the upper surface and side surfaces of the set body of the heating panel and the small joists are arranged. The advantage is that the floor heating structure covered with the heat radiating sheet can be easily obtained, the temperature of the installation portion of the small joist without a heating element can be effectively raised, and the entire floor heating installation area can be uniformly heated. is there.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a floor heating structure according to the present invention.

FIG. 2 is a perspective view showing an installation state of the floor heating structure.

FIG. 3 is a perspective view showing a specific structure of a small joist and a heating panel.

FIG. 4 is a perspective view showing a connection state of a heating panel.

FIG. 5 is a perspective view showing a folded state of the heating panel.

FIG. 6 is a perspective view showing a first step of a method for constructing a floor heating structure according to the present invention.

FIG. 7 is a perspective view showing a second step of the construction method.

FIG. 8 is a perspective view showing a third step of the construction method.

FIG. 9 is a perspective view showing a state in which a small joist and a heating panel are integrally covered with a heat dissipation sheet.

FIG. 10 is a sectional view showing another embodiment of the floor heating structure according to the present invention.

FIG. 11 is a sectional view showing still another embodiment of the floor heating structure according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discard 2 Ojo 3 Heating panel 6 Groove for wiring 7 Heat dissipation sheet 9 Electric heating wire (heating element) 10 Electric wire 11 Notch 12 Connecting member

Claims (7)

[Claims] In a floor heating structure in which a heating panel having a heating element is installed between small joists arranged at regular intervals on a discarded basis, adjacent heating panels are separated from each other by a width dimension of the small joist. A floor heating structure which is connected to each other by a flexible connecting member in a state of being longer and having a distance longer than twice the plate thickness of the heating panel. 2. The floor heating structure according to claim 1, wherein a heating element comprising an electric heating wire is provided on the heating panel, and the electric heating wires of adjacent heating panels are connected to each other by an electric wire. 3. A notch serving as an accommodating portion for a connecting wire is formed in a wire lead-out portion of the heating panel, and a wiring groove is formed on an upper surface of the small joist.
Floor heating structure as described. 4. A heat dissipating sheet for covering the upper and side surfaces of the heating panel and a heat dissipating sheet for covering the upper and side surfaces of the small joist are provided, and the side surface of the heating panel is brought into contact with the lateral portion of the small joist. The floor heating structure according to any one of claims 1 to 3, wherein the floor heating structure is configured to be installed on a discarded state. 5. A method for constructing a floor heating structure in which a heating panel having a heating element is provided between small joists disposed at regular intervals on a discard basis, wherein a plurality of flexible connecting members are used to connect the plurality of connecting members. After sequentially connecting the heating panels in a state where the heating panels are longer than the width of the small joists and separated by a distance longer than twice the thickness of the heating panels, each heating panel is folded back at the connection portion by the connection member. Forming a folded body of the heating panel, inserting the heating panel located at the end of the folded body between the small joists disposed at one end on the side of the discard, and then folding the heating panel A floor heating structure construction method characterized in that the floor heating structure is developed and sequentially inserted between small joists. 6. A small joist whose upper surface and side surfaces are covered with a heat radiating sheet are disposed at regular intervals on a discard basis, and a heating element is provided between the small joists and the upper surface and side surfaces are covered with a heat radiating sheet. 6. The floor heating structure according to claim 5, wherein the heating panel is inserted and the side panel of the heating panel is abutted on the side surface of the small joist. Construction method. 7. In a floor heating structure in which a heating panel having a heating element is installed between small joists disposed at regular intervals on a discard basis, the small joists extend along one side of the heating panel. And a heat radiation sheet for covering the top and side surfaces of the set consisting of the heating panel and the small joists.