DE19538686A1 - Electrical resistance heater for rooms - Google Patents

Abstract

Homes and buildings are heated by an electric resistance heater having a heating layer (11) formed by a mixture of graphite particles and a binder dilutable with water, which is spread, sprayed or screen printed etc. on a moisture absorbing backing plasterboard (2) and has a loading of 20 to 60 W/m<2>. A thermal insulating layer (4) is applied on the other side of the backing board. Preferably the plasterboard forms the complete interior wall of the heated area and is provided with two parallel metallic power supply electrodes (6), with a resistance between the electrodes of 40 to 120 ohm. Binder is preferably water glass.

Description

The invention relates to an electrical resistance heater for air conditioning in Apartments and buildings using an electric heatable electric conductive heating layer, consisting of a mixture of with a curable binder offset graphite particles, being on two parallel opposite sides of the heating layer metallic strip-shaped power supply electrodes are provided.

It has been shown that the windows used today in construction with high heat and Soundproofing closes up to 25 times more densely than windows, which take longer to install back. In older windows, the joint ventilation in several cubic meters of air the hour exchanged. In rooms with modern windows can be good However, sealing the humidity due to the constant release of water vapor by the People rise to high levels and cause moisture to build up. As a consequence of are moisture damage such as mold stains and mold growth on the walls too observe. The reason for this is the temperature inhomogeneity of the enclosure surfaces in general and the walls in particular as well as the fact that the surface temperature of the Enclosure areas are lower than the air temperature of the room. On cooler walls especially therefore on the outer walls, and in the side wall areas with less Air circulation, when there is a high level of water vapor saturation, the air is present Water vapor at the dew point as condensation because the amount of saturation is lower Temperature is lower.

This is related to the fact that the rooms, for example, primarily in apartments selectively by radiators operated with electricity, gas, steam, hot water or the like are heated, which are usually arranged below the windows. Through this Radiators the room air is heated and by forced convection gives the Indoor air exhausts heat to the surrounding areas. The room air is therefore always warmer than the enclosing surfaces, especially as the outer walls, which are constantly caused by heat conduction Dissipate heat to the outside.

With forced convection is a whirling up of dust particles and Disease germs and their transport in the room are connected, mainly for  Allergy sufferers and asthmatics suffer severe health problems, so that remedial measures are taken must become.

Constant opening and closing of the windows to replace the existing ones in the rooms Humidity is particularly significant in the cold season with significant losses Heating energy connected because the air due to the cooler enclosure surfaces Temperatures were warmed, their values above the sensation temperature of humans lie. The sensation temperature of the person and thus the comfort area becomes to approximately the same proportion by the temperature of the enclosing surfaces and the Air temperature determined. The exact ratio becomes inconsistent in the specialist literature specified, for example with 54% to 46%. The cooler the enclosure surfaces, for example the walls are, the higher the temperature of the room air must be.

These problems and requirements can be known from the prior art surface radiators that have become electrically conductive and can be heated by electricity Serve shift, do not do it justice. In the case of panel radiators, for example in the form of Heating wallpapers are made up of heating resistors consisting of wires or conductor tracks, which are usually laid in a meandering shape so that the heating resistors are sufficiently large Can have length. In the international patent application PCT WO 94/14012 for An example of a wall heating system based on a wall element is described Purposes of improving the indoor climate with one between the wall and the heater arranged reflection layer is equipped.

To adapt the heating according to the individual requirements of a heating room, the wall element has a molded part with receiving recesses in shape of grooves in which the heating resistors are accommodated. On the opposite of the The outer wall of the building is the back of the wall element Wells covered with the heating resistors covered with a reflective layer, so that the amount of heat given off to the outer wall can be kept low. Poses between the outer wall of the building and the wall element with integrated heating there is a circulating air flow through which all that is present in the room Air volume should be heated.  

As a disadvantage in general in this context it should be mentioned that by a circulating air heating essential parts of the room air a higher temperature level compared to the other parts that are not in the immediate vicinity of Heat source. In the case of forced ventilation by opening a window sash, however the warmer air masses through the action of the physical law of a room Gravity exchanged faster than the colder components, resulting in a Above-average heat loss can occur if there is strong heat in the room Differences in temperature due to the position of the radiator are noted.

As a result, the invention further aims at an electrical resistance heating Room air conditioning with a homogeneous heat radiation field, in which a forced Convection of the room air can be avoided. That is through room air conditioning To take into account, in which the radiant heating surfaces a comparatively low Have temperature, so that a radiation train between warm and cold Enclosing surfaces of the room can be avoided.

Known radiant heating surfaces, which are described in the book Electrical Space Heating by M. Palic, 1992, pages 142 to 144, have been described, the heating surfaces with embedded, meandering heating resistors have a surface load of 3500 W / m² on. This surface load results in a comparatively high surface temperature Such are preferably cast with silicone and processed into heating mats Surface heating elements in industrial and commercial use. To a radiation train To avoid getting out of the way, these heating mats are not suitable for heating a room.

Also known are those described in DE Patent 15 65 352 Wallpaper heaters with a heating foil made of electrically conductive plastic opposite supply lines, which only with considerable Effort can be set to different energy ranges. With cutouts in the to heating walls prepares the adaptation to local conditions in most cases Problems, so that these heaters could not prevail in practice. The same applies to the heating wallpapers which have individual heating wires lying next to each other.

Here, individual heating elements can not be easily removed without the Electrical continuity or the function of the other heating elements.  

As a result, the heating elements have cold zones in the area of the insulation surfaces. In The surroundings of the heating resistors result in warmer zones, the temperature of which is clear is above room temperature. Due to this fact, the recorded disadvantages.

The object of the invention is an electrical resistance heating under Use of an electrically conductive heating layer which can be heated by current and which is used for Air conditioning in apartments and buildings with a minimal surface temperature is operable, which is only slightly higher than the desired room temperature.

According to the invention, the object is achieved in an electrical resistance heater by that a heating layer is formed from a mixture based on graphite particles and a water-dilutable binder, which can be done by brushing, spraying, screen printing or the like can be applied directly to a moisture-absorbing carrier plate such that the area load is based on the electrical heating power of the heating layer 20 up to 60 W / m², whereby the carrier plate is a conventional one suitable for interior on the back is a plasterboard with a thermal insulation layer. Such Resistance heating is primarily inexpensive and with relatively simple means feasible because a commercially available plasterboard is used as the carrier board can and also the other components as well as the processing with little effort need.

The use of a plasterboard as an immediate support plate for an electrical Resistance heating is not yet known, because the plaster on a not seen for a longer period with the high temperatures of a conventional one Resistance heating can be loaded. That is due to the extremely low Area load in relation to the heat output is taken into account. The emerging Surface temperature is demonstrably only from tests by the applicants 3 to 5 K, on average 4 K above the desired air temperature of the room to be heated. A prerequisite for this is the one provided on the back of the plasterboard Thermal insulation, which is a flow of heat flowing from the heating layer into the outer wall does not allow.  

For this reason, it is also obvious that one in DE Offenlegungsschrift 32 08 428 proposed radiant heating system that converts the electrical energy into Thermal energy using a layer of a mixture of inorganic and organic Provides substances that are applied to wall panels made of metal or floor panels should not be operated with the proposed low surface temperature can.

The now proposed resistance heating causes an optimal heat and Moisture air conditioning by preventing any dew point from appearing on the walls noticeable. The required room ventilation can now be used without the risk of undesirably high heat loss can be made.

With this solution, the air is heated by the heating enclosing surfaces, the air is therefore always cooler than the surrounding areas, and condensation on the surrounding areas are excluded. Because the human temperature and thus the comfort area to an approximately equal extent by the temperature The enclosure area and the temperature of the air is determined by the warmer enclosures already have less heated indoor air than comfortable felt. The loss of thermal energy through the exchange of air is for this reason significantly lower. The required air exchange is also determined solely by the desired one Conditioning of the breathing air is determined, but not by additional conditions of the Building protection, for example to avoid moisture damage.

As a result, a further development of the invention is directed towards one at a time Prefabricated house belonging inner wall, which has a large plasterboard, the Provided on two parallel sides with ribbon-shaped metallic power supply electrodes is to cover with the heating layer, which is especially true in a low energy house is to consider. The surface load of the heating layer can be reduced to 20 W / m².

For retrofitting in existing buildings or in old buildings is for the subsequent Installation, because of the poorer thermal insulation compared to a low-energy house, a higher heat requirement and a resulting higher wing load up to 60 W / m² required. According to a preferred embodiment of the invention provided that the carrier plate for the heating layer by a commercially available, back with  a thermal insulation layer provided with plasterboard is formed on the Front is coated with the heating layer such that the total resistance, between measured the power supply electrodes, is about 40 to 120 ohms. At a Total resistance of 60 ohms is the heating power of the heating layer in combination with a commercially available plasterboard 40 W / m². In principle, it is possible to use plates with a produce higher heating output of up to 100 W / m². That still works with the purpose and does not conform to the task, is inconsistent and is accordingly beyond the claimed invention.

In the production of the heating layer, it is according to a further embodiment of the invention expedient that water glass is used as a binder for the graphite particles. Water glass is a relatively inexpensive binder that can be easily diluted with water can be applied to a plasterboard by brushing, spraying, screen printing or the like.

Contrary to the knowledge presented by experts in DE patent specification 24 38 984, which has been cemented by tests carried out accordingly that when in use of water glass adhesives between a layer of soot and the Power supply electrodes can not enter a power line, surprisingly could be a very good power line can be achieved if the water glass in the proposed Procedure is handled. In the context of the invention it is further provided that the ratio of the volume fractions based on the starting constituents graphite particles to Binder in the form of water glass can be varied in the range from 1: 1 to 2: 1 without contacting the electrically conductive layer with the power supply electrodes affect.

Finally, it is provided in the context of the invention that the curing of the Water glass solution with the help of an acidic, preferably gaseous reaction component in Form of CO₂ can be accelerated. The processability of the binder can then by dilution with water, for example when applying by spraying or brushing be improved. Although due to the moisture absorption of the plasterboard rapid drying of the heating layer is guaranteed, but can in some cases faster curing may be of particular importance. In these cases, a Curing with CO₂ a quick setting of the water glass can be achieved.  

The invention will be described below using an exemplary embodiment and with reference to drawings are explained in more detail. In the accompanying drawings shows

Fig. 1 shows the inside view of a room with a belonging to a low-energy house side wall and a gable wall, which is built of a conventional masonry,

Fig. 2 shows a cross section through a one-layer board covered with a heating layer made of plasterboard and

Fig. 3 is a front view of the plasterboard one-man board shown in Fig. 2 in a schematic representation.

Fig. 1 shows a highly schematic view of the interior of a room with a right side wall 1 , which is provided on the front with large plasterboard 2 any cut. The gypsum plasterboards 2 are smoothed and sanded in one piece or without joints. On the downside there is a solid wood-based panel 3 and, as a thermal insulation layer 4, a infill with mineral wool mats for thermal insulation and sound insulation. At the height of the upper edge of the ceiling 5 , a power supply electrode 6 extending over the wall length is fastened. Depending on the current strength to be expected, the current supply electrode 6 consists of a metal strip, of a strip which is formed from a metal foil, or of a strip of a metal color if the surface heating power is to be chosen lower. A second power supply electrode 6 is arranged parallel to the upper power supply electrode 6 at the level of the floor edge 7 . Both power supply electrodes 6 are provided at the ends with connections which are in contact with copper lines 8 which are led in a cable cladding to a busbar or to a power supply device 9 operated with a protective extra-low voltage, this being controllable in a known manner of working.

A heating layer 11 , which consists of a mixture of graphite particles with a water-dilutable binder, is applied to the area enclosed between the two parallel spaced-apart power supply electrodes 6 , water glass being used in the exemplary embodiment. Based on the initial volume, the mixing ratio of graphite particles to water glass is 1: 1, in which a very easily spreadable mass is formed, with which the front of the plasterboard 2 can be coated in a single application. The application can be done with a conventional coating roller or by spraying. A particularly uniform coating can be achieved in that the heating layer 11 is applied in the form of a screen print. In this case, the mixing ratio can be increased in favor of the graphite particles.

The variation of the mixing ratios should not, however, go beyond a proportion of 2: 1, because the application of graphite is made unnecessarily difficult by a higher proportion of graphite and, ultimately, the resistance built up between the two current supply electrodes 6 can be changed by the thickness of the applied layer. The desired resistance values were empirically achieved by deleting in a good approximation with a deviation value of 10%.

Immediately after applying the mixture to the gypsum plasterboard 2, the heating layer 11 dries fairly quickly due to the rapid absorption of moisture by the gypsum plasterboard 2 , so that rapid further processing of the interior wall components is possible in the manufacture of a house from prefabricated components. If necessary, curing can be accelerated with an acidic gas such as CO₂. After the heating layer 11 has completely hardened, a smooth, smudge-resistant surface is formed depending on the chosen coating method, which can be provided with an optically appealing coating, with a wallpaper or the like.

In order to heat the wall 1 , a protective low voltage of 60 V is applied to the two power supply electrodes 6 , which is provided by the power supply device 9 . The surface temperature of the heating layer 11 was measured. These measurements resulted in temperature inhomogeneities of no more than ± 2 K over the entire heating surface. In long-term operation, the air in the room takes on temperature values which are only 2-5 K below the surface temperature of the heating layer 11 . The reason for this is the large-area coating of a room with a heating layer 11 that can be realized with the aid of the invention, the area proportion of which on the walls should be more than 70%.

In several experiments it was possible to demonstrate that when the electrical resistance heating is operated, even at an air humidity of 80% generated at 35 ° C., moisture does not condense on the wall surfaces covered with the heating layer 11 nor on the indirectly illuminated unheated wall surfaces of the room. The large-area heating in the area of long-wave infrared radiation also creates a homogeneous radiation climate, so that a radiation draft between warm and cold surfaces of the room is avoided. This creates a comfortable atmosphere that promotes the well-being of the people in the room. Due to the homogeneous heating, forced convection of the room air is avoided and the whirling up of dust-like pollutant particles or pathogens is reduced.

For retrofitting and retrofitting in existing buildings, a one-man board 12 made of plasterboard, shown in cross section in FIG. 2, is assumed within the scope of the invention, which has a thermal insulation layer 4 on the back. The one-man plate 12 , which has an average length of 2.5 m to 3.0 m and a width of 0.6 m, is provided according to FIG. 3 on the opposite sides on the narrower end edges in each case with a current supply electrode 6 which is connected to the ends of one long side are extended to a contact section 14 , which serves both for connecting a plurality of panel heating elements and for connecting a low-voltage source 9 . After the end portions of the one-man plate 12 have been provided with the current supply electrodes 6 , the application of the heating layer 11 can be carried out as described above. Immediately after the mixture has been applied to the plasterboard 2 , the resistance measured between the two power supply electrodes 6 is 13 k ohms when the heating layer 11 is wet. After drying out, the resistance between the power supply electrodes is 60 ohms. The screen printing method is particularly well suited for applying the heating layer 11 to a one-man plate 12 . The desired resistance values can be varied very precisely by means of screen printing, which is particularly advantageous if a gable wall 15 shown in FIG. 1 a is to be heated, which was built from a common masonry with openings 16 . Shortened one-man plates 18 are suitable for heating the not so high wall pieces 17 , in which first one-man plates 12 are provided with corresponding current supply electrodes 6 . In order to adjust the heating power, the shortened one-man plates 18 are coated with a heating layer 11 by means of screen printing, which has a total resistance of, for example, 300 ohms. The installation of the one-man shortened plate 18 is carried above and below the window is apparent break-through 16 as shown in Fig. 1a with a non-illustrated current-conducting connection is established between the current supply electrodes 6 fenstereinwärts directed. Thereafter, the heating of the gable wall 15 can be started up after connecting the power supply electrodes 6 to the power supply device 9 .

Claims (6)

1. Electrical resistance heating for air conditioning in apartments and buildings using an electrically conductive heating layer which can be heated by current, consisting of a mixture of graphite particles mixed with a hardenable binder, metallic strip-shaped power supply electrodes being provided on two parallel sides of the heating layer, characterized in that the mixture forming a heating layer ( 11 ) is composed on the basis of graphite particles and a water-dilutable binder and can be applied directly to a moisture-absorbing carrier plate by brushing, spraying, screen printing or the like in such a way that the surface load is related to the electrical heating power of the heating layer ( 11 ) Is 20 to 60 W / m², the carrier plate being formed by a conventional plasterboard plate ( 2 ) which is suitable for interior construction and has a thermal insulation layer ( 4 ) on the back becomes. 2. Electrical resistance heating for air conditioning in apartments and buildings according to claim 1, characterized in that the carrier plate is formed by a complete inner wall provided for a prefabricated house, which has a large-area plasterboard ( 2 ) which on two parallel sides with ribbon-shaped metallic power supply electrodes ( 6 ) is provided. 3. Electrical resistance heating for air conditioning in apartments and buildings according to claim 1 and / or according to claim 2, characterized in that the carrier plate by a commercially available, on the back with a heat insulation layer ( 4 ) provided one-man plate ( 12 ) made of plasterboard, which is formed on the The front is coated with a heating layer ( 11 ) based on graphite particles and a water-dilutable binder such that the total resistance, measured between the current supply electrodes ( 6 ), is 40 to 120 ohms. 4. Electrical resistance heating for air conditioning in apartments and buildings according to one or more of claims 1-3, characterized in that the carrier plate is formed by a shortened, commercially available one-sided plate ( 18 ) made of plasterboard with a heat insulation layer ( 4 ) is coated on the front with a heating layer ( 11 ) based on graphite particles and a water-dilutable binder such that the total resistance, measured between the current supply electrodes ( 6 ), is approximately 300 ohms. 5. Electric resistance heating for room air conditioning in apartments and buildings after one or more of claims 1 to 4, characterized in that as a binder Water glass is used. 6. Electric resistance heating for room air conditioning in apartments and buildings after one or more of claims 1 to 5, characterized in that the ratio of the volume fractions based on the starting components of the graphite particles Binder in the form of water glass ranges from 1: 1 to 2: 1.