Low cost radiant floor comfort systems
A rapidly assembled pre-fabricated array of heating elements, such as tubing or wire, on a rigid mesh, for use in radiant panel heating and/or cooling systems, reduce costs by streamlining both the design layouts and the labor operations to fabricate and install the systems. The pre-fabricated arrays may be installed with the mesh on the finish floor side for additional protection of the heating elements during and after installation.
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This invention was made with State of California support under California Energy Commission contract number 500-02-026. The Energy Commission has certain rights to this invention.
BACKGROUNDThis subject matter of this application relates to radiant floor heating and cooling systems, and particularly to systems that place hydronic tubing or electrical heating cables in contact with indoor room or outdoor surfaces.
Radiant floors are widely recognized as the most comfortable choice among heating systems. As a result, the radiant floor market has grown rapidly. However, the market could be much larger if installed system costs could be lowered significantly. Installations have been largely limited to custom homes where the owners are willing to pay more for improved comfort. Current radiant heating systems are more likely to be installed at sites where cooling systems are not necessary. Cooling is generally provided by ducted forced air systems, which for a modest additional expense can deliver heating as well. By comparison, combining radiant heating with forced air cooling is much more expensive to install. However, there is the potential in dry climates to install ductless systems that can deliver cooling as well as heating through floor tubing. Many rapidly growing housing market areas are in the dry climates of the U.S. southwest and mountain states. Production builders construct more than 75% of new homes in these areas. These volume homebuilders are more likely to consider radiant systems if costs can be reduced, because homebuyers are attracted to many radiant system features including superior comfort, high energy efficiency, and low noise.
There are additional market opportunities for lower-cost outdoor panel heat transfer systems. These include snow-melt and patio heating systems, patio cooling systems, and swimming pool solar heating systems that circulate pool water through tubing in surrounding or nearby concrete paving.
The most economical radiant floor systems place linear tubing or electrical conductors (wires) in concrete slabs, where reinforcing steel provides a matrix for securing the linear heat transfer elements in a desired pattern. The concrete transfers heat laterally, allowing wider spacing of the elements. For concrete slab construction, a typical method involves a concrete crew placing steel reinforcing wire, which is typically a grid-type reinforcing mesh that arrives in a rolled form and then is straightened, cut, and laid throughout the formed area. A radiant floor specialty crew then manually secures the tubing or wire onto the top of the reinforcing grid at 2′ to 3′ intervals with wire or cable ties. Tying the tubes or wires in place is a labor intensive, time consuming, process. The installers must either repeatedly bend over or be on their hands and knees for extended periods of time. In addition to working for long periods in uncomfortable positions, the installers must have considerable dexterity to secure the ties without damaging the tubing or wires.
The heating elements typically arrive at the site in rolls, and if the element is hydronic tubing, its “memory” of the rolled shape complicates the task of securing it in straight runs on the mesh. Radiant floor designs typically use customized serpentine and rectangular spiral layouts. These layouts or circuits can be complex because interior wall locations must be marked before the circuits are placed. The layout patterns are usually configured room-by-room with connecting lines entering through doorways to avoid passing under interior walls, thereby minimizing the danger that wall framing fasteners will penetrate and damage the tubing or wire.
The ends of the heating elements ultimately meet at a manifold or panel that becomes the distribution point for a group of “circuits,” whether hydronic or electrical. After the circuits are run, the concrete crew that formed the slab edges returns to pour the slab over the heating elements. During the pour, they typically reach blindly through the wet concrete with “J-hooks” to pull the reinforcing mesh up near the horizontal centerline of the slab. Because the mesh is not typically flat, and the ties are widely spaced, this operation sometimes results in pulling heating elements too near the surface, where they are more vulnerable to damage. If the system is hydronic, the tubing is pressurized during the pour, and a sudden loss in pressure indicates that the tubing has been punctured.
Radiant systems that are not placed in concrete slabs are relatively more expensive because they require the addition of a layout matrix to guide the layout patterns. Such systems usually require either closer spacing of the heating elements or additional components to spread heat laterally. The prior art includes several novel strategies for reducing the cost of “raised floor” radiant technologies that do not surround the linear heat transfer elements with concrete. For example, the Applicant's “low mass” radiant system shown in U.S. Pat. No. 4,782,889 uses a corrugated deck that spans across the framing members to hold the tubing, and spread heat laterally across the floor. A subsequent technology (U.S. Pat. No. 5,788,152) uses a composite plywood-aluminum deck to accomplish the same three functions. Both of these systems would benefit from use of a tubing product that arrives in a serpentine pattern rather than in rolls.
The above factors suggest a need and opportunity for improved radiant panel methods that reduce costs and enhance installation reliability.
SUMMARYThe subject matter of this application is directed to an improved heating element product and methods for fabricating and installing such elements, including radiant panel systems that reduce costs by streamlining both the design layouts and the labor operations to fabricate and install the systems. The improved products and methods include forming a heating element, such as hydronic tubing in a “figure-8” pattern that facilitates installation of the tubing in certain layouts. The subject matter of the application also provides, a method of rapidly assembling pre-fabricated arrays of heating elements, such as tubing or wire, on a rigid mesh. According to the subject matter of this application, the pre-fabricated arrays may be installed with the mesh on the finish floor side for purposes of protection of the heat transfer elements. These and other improvements will be further described in the following sections.
BRIEF DESCRIPTION OF THE DRAWINGSThe subject matter of this application will be described in detail with reference to the following drawings in which like reference numerals refer to like elements and where:
Although features of the subject matter of this application may be implemented use in a variety of deployment patterns, standardization can be maximized using a serpentine pattern in which the linear heat transfer element, such as tubing or wire, enters near one corner of a rectangular grid and is placed in a repetitive back-and-forth alignment of parallel runs. The “memory” problem for plastic tubing wound on a spool can be minimized an/or eliminated with a “figure-8” winding, which can be accomplished according to the subject matter of this application.
During the winding process, tubing 1 being produced by the extruder 2 is wound on two mandrels 3a and 3b of a winder 6 rather than on one larger mandrel as used in a standard tubing extrusion process. The diameter of the mandrels 3a, 3b will typically range from 6″ to 12″. As the tubing 1 from the extruder 2 is freshly wound about the mandrels 3a and 3b, the tubing 1 takes a “set” such that curved tubing segments 4 remain curved and straight sections 5 remain straight after removal from the winder 6. In an embodiment, the winder 6 tilts and rotates relative to the extruder 2 so that the tubing 1 clears the mandrels 3a, 3b as winding proceeds. As shown in
The winding process continues until the winder 6 is full. The tubing 1 is then cut and the cut end from the extruder 2 is connected to a second winder. The coiled tubing 1 is then removed from the first winder 6. If the heating element being extruded from the extruder 2 is a cross-linked polyethylene tubing (PEX), the coil of tubing then proceeds to a cross-linking operation. The completed coil of tubing may either be packaged for shipment or deployed and secured immediately to a grid in a process to be described below.
A common spacing of the tubing 1 on the grid 11 is 12″ on center. The configuration or pattern shown in
Another advantage of the figure-8 tubing 1 is apparent in considering installation of the channel fins 33. For example, conventional rolled tubing must first be secured to a subfloor to straighten the tubing before the channel fins can be placed. With the figure-8 tubing 1, the tubing 1 need not be secured to the subfloor 31 before the channel fins 33 are placed. Instead, the tubing 1 can be held by the channel fins 33 which are secured to the subfloor 31. This process works because the channel fins 33 can readily be snapped over the straight sections 5 of the figure-8 tubing 1.
The figure-8 tubing 1 may also benefit installations of the “Low Mass Hydronic Radiant Floor System” shown in U.S. Pat. No. 4,782,889 (1988). In this application (not shown), tubing is held by and in the grooves of a corrugated metal deck that replaces the subfloor in framed construction. As with respect to
In practice, one of the most cost-effective radiant heat designs combines low piping and manifold costs with relatively low pressure drop to minimize pump size and energy use. Optimal circuit lengths, tubing sizes, and tube spacings often dictate arrays that require two grid panels. For example, two 7′×20′ grids may be placed end-to-end to form a 7′×40′ assembly, or side-by-side to form a 14′×20′ assembly. For U.S. markets where ½ diameter (nominal) tubing is most common, the resulting 280 square foot area is appropriate for the optimal circuit.
Although the subject matter of this application has been described with reference to various exemplary embodiments, it is to be understood that the subject matter is not limited to the exemplary embodiments or constructions. To the contrary, the subject matter of this application is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the exemplary embodiments are shown in various combinations and configurations, others combinations and configurations, including more, less, or only a single element, are also within the spirit and scope of the invention.
Claims
1. A method of fabricating a heating/cooling element for a radiant comfort system, comprising:
- forming the heating/cooling element of a material having a shape memory;
- winding the heating/cooling element into a pattern of turn portions and straight portions onto a winding device;
- removing the heating/cooling element from the winding device after a predetermined period so the heating/cooling element retains the pattern of turn portions and straight portions.
2. The method of claim 1, wherein winding the heating/cooling element includes receiving the heating/cooling element about two mandrels disposed on the winding device so that the turn portions turn more than 180 degrees about each mandrel and wind alternately clockwise and counterclockwise about the two mandrels, and the straight portions are disposed between the mandrels.
3. The method of claim 1, wherein the heating/cooling element is an extruded polymeric tube.
4. The method of claim 3, wherein the polymeric tube is comprised of one of a high density polyethylene or a cross-linked polyethylene.
5. The method of claim 1, wherein the heating/cooling element is a tube connectable to a fluid source to heat/cool an area.
6. The method of claim 1, further comprising:
- securing the heating/cooling element to a substrate in a serpentine pattern with the turn portions open to approximately 180 degrees and the straight portions are substantially parallel to one another; and
- placing a covering over the heating/cooling element and the substrate to protect the heating/cooling element and facilitate heating/cooling transfer.
7. The method of claim 6, wherein the heating/cooling element is a tube connectable to a fluid source to heat/cool an area.
8. The method of claim 6, wherein the substrate is a rectangular mesh grid and the straight portions are oriented transverse to a length of the rectangular mesh grid.
9. The method of claim 6, wherein the substrate is a structural sheet and the covering is a poured material that covers the substrate and the heating/cooling element and hardens after pouring.
10. The method of claim 6, further comprising placing at least one metallic heating/cooling transfer element in contact with the heating/cooling element before placing the covering.
11. The method of claim 6, wherein the substrate is a structural sheet and the covering is a rigid panel.
12. The method of claim 6, wherein the substrate is a corrugated metal sheet having troughs narrower than an outer dimension of the heating/cooling element and the heating/cooling element is placed into the troughs before placing the covering.
13. A method of installing a pre-fabricated radiant comfort system, comprising a mesh grid and a flexible linear heating/cooling element attached to one side of the grid to form a pre-fabricated assembly, the method comprising:
- installing the pre-fabricated assembly at an installation location with the grid disposed between the heating/cooling element and the finish surface; and
- covering the assembly with a finish surface.
14. The method of claim 13, wherein the grid element is held in a substantially vertical position while the element is being attached thereto to form the pre-fabricated assembly.
15. The method of claim 13, wherein the element is attached to the grid using a motorized wire-wrapping tool.
16. The method of claim 13, wherein the heating/cooling element is a flexible tube for conveying a liquid heating/cooling transfer fluid.
17. The method of claim 13, wherein the heating/cooling element is an electrical wire.
18. The method of claim 13, wherein the mesh grid is comprised of a metal and the finish surface is concrete.
19. The method of claim 13, further comprising joining at least two pre-fabricated assemblies by the heating/cooling element.
20. The method of claim 19, wherein the two assemblies are foldable about the joining element without damaging the element.
21. The method of claim 20 where the folded assembly allows a required minimum bend radius of the heat transfer element at the fold line.
Type: Application
Filed: Jun 28, 2005
Publication Date: Jan 25, 2007
Applicant: DAVIS ENERGY GROUP, INC. (Davis, CA)
Inventors: Richard Bourne (Davis, CA), Marc Hoeschele (Davis, CA)
Application Number: 11/167,160
International Classification: B21D 53/02 (20060101);