Patent Publication Number: US-2006000184-A1

Title: Method of installing a radiant density floor heating system

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application is a divisional of U.S. patent application Ser. No. 10/637,282 filed on Aug. 8, 2003, currently pending, the entire disclosure of which is hereby incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention relates generally to a multi-layer conductive/insulation material having both conductive and insulating properties that is particularly suitable for use under a concrete slab, and in particular relates to a method of installing a radiant density floor heating system incorporation such a multi-layer conductive/insulation material.  
      Materials to control the movement of heat have been used for many years and in many forms depending upon the desired use. For example, a variety of materials such as sawdust, straw, wool blankets and bats of foam or fiberglass have been used for insulation. However, special uses require materials having special insulating characteristics. One of these special uses is to prevent radiant heat transfer under concrete slabs. In many parts of the country houses, driveways and the like are constructed on concrete slabs laid either directly on the ground or on sub-flooring. Many of these types of structures are heated through hot water systems or electrical circuits embedded in the concrete. When such construction is used the radiant heating goes upward into the room and downward through the ground or sub-flooring. It is therefore desirable to prevent or substantially reduce the amount of heat lost to the ground. One such means for reducing heat loss is to install a system of reflective cushioning material with sealed pockets of air.  
      Numerous suggestions for insulating materials for use under concrete slabs have been made. For example, U.S. Pat. No. 6,188,839 to Pennella discloses a two-layer insulation assembly for use under a concrete slab in a radiant heating system. These assemblies include a rigid honeycomb panel forming a plurality of insulating pockets alternatively disposed on the top and bottom surfaces of the honeycomb and a reflective layer above the honeycomb to reflect heat away from the honeycomb panel.  
      In U.S. Pat. No. 6,514,596 to Orologio there is described the use of separating sheets to thermally separate construction materials from underground soils to retain the soil in place and to serve as moisture barriers. This patent discloses an insulating material having thermal and moisture resistance. The sheet includes a structure in which a metal foil is bonded between two bubble-wrap layers. The foil is separated from the concrete by an insulation air cellular cushioning layer. The insulating material described in this patent is stated to reduce heat transfer.  
      U.S. Pat. No. 6,248,433 to Annestad discloses a multi-layer thermal material used, for example, to cover ice skating rinks. The multi-layered material includes an outer polyester sheet, an insulation layer and an aluminum film layer positioned between an inner surface of the polyester sheet and an outer surface of the insulation layer. The aluminum film may be coated onto the polyester sheet. The thermal material of Annestad is used to keep cold in and heat out.  
      In view of the state of the art, there is a desire to provide a conductive/insulation pad suitable for use under a concrete pad that prevents or substantially reduces the radiant energy from spreading out under the concrete slab.  
     BRIEF SUMMARY OF THE INVENTION  
      Despite numerous attempts to provide an effective product that can be used to insulate under concrete slabs, the materials presently used in the art are not altogether effective. Although there is ample evidence that air cellular cushioning products work in insulating under concrete slabs, it has been further suggested that the performance is from the foil reflecting radiant energy. It has been found that this theory is incorrect as it is a well-known fact that coating the foil surface or applying a film to it will substantially reduce the reflectivity of the foil. Moreover, it has been found that the use of the conductive/insulation pad of this invention reduces or eliminates ground water intrusion into the concrete slab. Cold ground water will reduce the performance of a radiantly heated slab. Secondly, the aluminum foil does not act as a reflector as well as it does a conductor of heat allowing radiant energy to spread out under the slab improving performance.  
      In accordance with the present invention, there is provided a multi-layered conductive/insulation pad. In a first embodiment of the invention a multi-layer conductive/insulation pad is provided having, in order, a first polymer layer, a conductive layer, such as a thin foil of metal or a metallized thermoplastic film, laminated to the first polymer layer, a second polymer layer laminated to the side of the conductive layer opposite the side of the first polymer layer. At least one air cellular cushioning layer is laminated to the side of the second polymer film opposite the conductive layer. Optionally, a protective polymer layer is laminated to the first air cellular cushioning layer on the opposite side of the second polymer layer. The first and second polymer layers are laminated to the opposite sides of the conductive layer to protect the layer from oxidizing and to protect the layer from the lime in the curing concrete, and, when used directly on the soil, the alkali content in the soil. The insulation component (air cellular cushioning material) prevents the ground water intrusion into the concrete slab, as well as heat loss into the cold ground water. The conductive layer, i.e., foil or metallized film, conducts the heat throughout the layer allowing radiant energy to spread out under the slab.  
      For the product to be efficient, the conductive layer needs to be as close as possible to the concrete slab, without having any insulation between the slab and the conductive layer. An advantage of the pad of the present invention is that the air cellular cushioning layer insulation between the conductive layer and the concrete slab is eliminated which makes the conductive layer a more effective conductor of heat allowing radiant energy to spread out under the concrete slab.  
      In another embodiment of the present invention the multi-layer construction of the pad of the first embodiment has added thereto a second air cellular cushioning layer laminated to a third polymer layer on the side opposite the first air cellular cushioning layer. Optionally, a protective polymer layer is laminated to the second air cellular cushioning layer on the side opposite the third polymer layer.  
      After the ground or sub-flooring has been prepared for pouring a concrete slab, the conductive/insulation pad of one of the embodiments of the present invention is placed directly on the soil or the sub-flooring. Typically, a heating element is placed on the conductive/insulation pad, generally slightly above the layer, so that some of the concrete may settle under the heating element and so that when the heating element is activated, heat generated from the heating element is conducted away from the pad allowing radiant energy to spread out under the concrete pad. After the concrete slab with the heating element embedded therein dries, a floor surfacing such as tile or the like may be laid.  
      It is, therefore, an object of the present invention to provide a conductive/insulation pad having a conductive component consisting of a foil or metallized film protected by polymer films on both sides and an insulation component consisting of at least one air cellular cushioning layer.  
      Another object of the present invention is to provide a reflective layer that conducts heat throughout the layer allowing radiant energy to spread out under the slab and preventing dispersal of heat below the reflective surface.  
      An additional object of the present invention is to provide a concrete pad having a foil or metallized film that is protected by pigmented polyethylene on one side for surface identification purposes.  
      Yet another object of the present invention is to provide a concrete pad in which the insulation layer is protected from sharp ground objects by an additional layer of heavy-duty polymer film.  
      Other objects, features and advantages of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:  
       FIG. 1  is a perspective view in partial section of the conductive/insulation pad of the present invention as it is used to conduct radiant heating across a concrete floor;  
       FIG. 2  is a diagramic enlarged sectional view of a first embodiment of the conductive/insulation pad of the present invention taken along line  2 - 2  of  FIG. 1 ;  
       FIG. 3  is a diagramic enlarged sectional view of a second embodiment of the conductive/insulation pad of the present invention also taken along line  2 - 2  of  FIG. 1 ; and  
       FIG. 4  is another perspective view in partial section of the conductive/insulation pad of the present invention illustrating use in another environment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.  
      Referring more particularly to the drawings, there is shown in  FIG. 1 a  perspective view of a radiant heating assembly  10  showing a conductive/insulation pad  20  overlaying the ground  12 . A heating element  14  is placed above the conductive/insulation pad  20  and positioned so that the heating element  14  may be surrounded by the slab  16 . The slab  16  comprises a layer of concrete or other cementitious material and is poured so that it covers the conductive/insulation pad  20  and embeds the heating element  14 . After the concrete slab  16  dries, the slab may be covered with tile  18  or other type of flooring material.  
      In  FIG. 2  there is shown a first embodiment of the multi-layer conductive/insulation pad  20  of the present invention. This embodiment is a four or five layer construction wherein there is a first polymer layer  22 . Layer  22  is a clear or pigmented polymer layer. Following the first polymer layer  22  is a conductive layer  24  laminated to the first polymer layer  22 . The next layer is a second polymer layer  26  laminated to the side of the conductive layer  24  opposite the side of the first polymer layer  22 . The next layer is at least one air cellular cushioning layer  28  laminated to the side of the second polymer layer  26  opposite conductive layer  24 . An optional protective layer of polymer material  30  is laminated to the air cellular cushioning layer  28  to the side opposite the second polymer layer  26 . The protective layer  30  is a heavy-duty polymer layer to protect the air cellular cushioning layer from sharp ground objects. The concrete pad  20  conducts radiant the heating provided by heating element  14  upward through the concrete allowing radiant energy to spread out under the concrete pad. The pad is flexible allowing easy installation and may be rolled up so that it can be easily transported.  
       FIG. 3  illustrates another preferred embodiment of the conductive/insulation pad of the present invention, pad  20   a . This embodiment the uses the five-layer construction of the first embodiment and adds a second air cellular cushioning layer  32  laminated to the third polymer layer  34  on the side opposite the first air cellular cushioning layer  28 . An optional protective polymer layer  30  is laminated to the second air cellular cushioning layer  32  on the side opposite side of the third polymer layer  34 .  
      The polymer layers may be a polyolefin, such as polyethylene (PE), low density polyethylene (LDPE), polypropylene (PP), co-polymers of polyethylene and polypropylene, polyethylene terephthalates (PET), polyamide, and polyvinyl chloride. A preferred polymer layer is a PETROTHENE® NA345-013, a low density polyethylene film extrusion grade from Equistar Chemicals, LP. These films are preferably extruded at a thickness of about 0.5 mil to about 3.0 mils. The first and second polymer films are coated or attached to both sides of the conductive layer to protect the layer from oxidization and the lime in the curing concrete. The optional protective layer is a heavy-duty layer to protect the air cellular cushioning layer from sharp ground objects and alkaline content in the soil. The first polymer layer may be colored or pigmented. The heavy-duty protective layer may also be a durable non-woven polymer film scrim. By coloring the first polymer layer the user may readily be able to determine which side of the pad to have facing upward toward the slab.  
      The conductive layer is material that will reflect heat. In particular a thin foil metal or metallized thermoplastic film having conductive/reflective properties may be used. Preferably the foil is aluminum, which has a lower emissive value of less than five percent on each surface to essentially eliminate heat transfer by radiation. The polymer layers on either side of the reflective layer reduce the oxidation of the conductive layer helping to retain the reflectivity of the layer. The conductive/reflective layer, i.e., foil or metallized film, conducts the heat allowing radiant energy to spread out under the slab.  
      The air cellular cushioning layer or layers provide both thermal conduction and convection insulation and, in combination with the conductive/reflective surface, excellent radiation insulation. The air cellular cushioning layer has a first thermoplastic film having a plurality of portions wherein each of said portions defines a cavity and a second thermoplastic layer in sealed engagement with said first layer to provide a plurality of closed cavities. Such air cellular cushioning layers are well known in the industry and are readily available from Sealed Air Corporation. The insulation component (air cellular cushioning layer) prevents the ground water intrusion into the concrete slab as well as heat loss into the cold, water/ground layer.  
      The conductive/insulation pads  20  and  20   a  offer significant resistance to heavy loading, whereby appreciative non-breakage of air bubbles is often found. Preferably, outer polymer layers are made slightly thicker than the inner layers to better resist abrasion.  
      The multi-layer conductive/insulation pads are lightweight and thin. For example, a typical pad weights about 1.20 to 1.50 ounces per square foot. The pads are typically from about 0.2 cm to about 0.8 cm thick, preferably about 0.3 to about 0.35 cm. thick. The thinness and flexibility of the pads facilitates the manufacture, transportation and handling of rolls of different desired sizes.  
      Referring now to  FIG. 4 , there is provided an alternative embodiment of a radiant heating assembly  10   a  showing a conductive/insulation pad  20  installation overlaying the a sub-flooring  12   a . The pad  20  is the same pad used in the embodiment of  FIG. 1 . As in  FIG. 1 , a heating element  14  is placed above the pad  20  and positioned so that the element  14  is surrounded by the concrete slab  16 . The concrete slab  16  is poured so that it covers the pad  20  and embeds the heating element  14 . After the concrete slab dries, the slab may be covered with tile  18  or other type of flooring material.  
      Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.