Heated mats for melting snow and ice from outdoor surfaces

A device for melting snow and ice on outdoor surfaces such as driveways, sidewalks, and walkways, comprising:

• a first mat defining an interior chamber, said mat being substantially closed off about the circumference thereof, and comprising a plurality of concentrically-arranged tubes spaced apart in said interior chamber and mounted therein through which may flow a mixture for heating the surfaces of said first mat defining said interior chamber, each said tube having an inlet end and an outlet end;
• an inlet manifold passageway with which each said inlet end and each said outlet end of said plurality of tubes is in fluid communication, so that mixture flowing through said inlet passageway flows through each of said plurality of tubes from each said inlet end thereof to each said outlet end thereof and back to said inlet passageway, said inlet passageway having a first intake end and a second outtake end, said inlet passageway also being mounted in said interior chamber;
• a return-flow manifold passageway substantially parallel to said inlet manifold passageway and comprising a first intake end and a second outtake end;
• a first interconnecting passageway having a first end in fluid communication with said outtake end of said inlet passageway and a second end in fluid communication with said intake end of said return-flow passageway, whereby the mixture may flow from said inlet passageway to said return-flow passageway;
• a first valve positioned in said interconnecting passageway for controlling the flow of mixture therein;
• a second interconnecting passageway having a first end in fluid communication with said outtake end of said inlet passageway, and a second end remote therefrom for fluid communication with an inlet passageway of another like-mat;
• a second valve positioned in said second interconnecting passageway for controlling the flow of mixture from said outtake end of said inlet passageway to another like-mat;
• a third interconnecting passageway having a first end in fluid communication with said intake end of said return-flow passageway, and a second end remote therefrom for fluid communication with the return-flow passageway of another like-mat;
• and
• a third valve positioned in said third interconnecting passageway for controlling the flow of mixture between adjoining return-flow passageways of two like-mats, whereby the flow of mixture through one or more mats may be selectively controlled.