Electric floor heating system

Radiant floor heating has long been used for the heating of floors and/or occupied space above the floor. This type of heating system has advantages over other heating systems in several respects, most notably in the comfort level of the occupants. The heat from the floor naturally rises to provide a relatively uniform and draft free warmth. However, there are disadvantages as well. Hot air ducts that extend beneath the floor in order to warm it are subject to complexity and high construction costs and also require space for the ductwork.

Hydronic floor heating systems have become popular more recently. However, a hydronic system requires tubing which is typically installed in a concrete floor slab and connected to a pump and boiler system. Although a comfortable radiant heating effect is usually provided, these installation complexities generally restrict the use of hydronic systems to new construction and relatively large areas that are to be heated. They are usually not well suited for remodeling applications.

Electrically resistive heating systems having a meshwork structure which holds heating elements have been proposed for various heating applications. However, the systems that have been proposed in the past have not been suitable for floor heating applications for a variety of practical reasons. For the most part, they have been too thick to allow their use beneath floor covering materials. Also, connecting the electric heating elements to a source of power has presented significant problems both practically and aesthetically. Securely attaching the heating elements has been an additional problem. The tendency for the elements to generate significant electromagnetic fields has been another cause for concern.

The heating element is arranged in a "spike" pattern that minimizes the electromagnetic field generated when the element is energized. The heating element arrangement includes side by side inward and outward runs that are held in aligned openings formed between the twisted warp strands of the mat. The fields in the two side by side runs essentially cancel each other. In addition, connecting runs from each inward run to the next outward run are arranged end to end in what is essentially a single line with the current flowing in the same direction in each connecting run. A return wire from the last inward run extends along one edge of the mat adjacent to the linearly arranged connecting runs, again essentially cancelling the electromagnetic fields. The return wire also allows the lead wires to be conveniently located at one end of the mat where the power leads can be connected without having to provide electrical access elsewhere on the mat.