 Electrically heated glass was first developed in World War II to prevent aircraft windshields from frosting over and obscuring visibility. Since then, this technology has been become almost universally used in aviation. It has even reached supermarket freezers, where glass doors must remain clear for customers to be able to see the merchandise.
Electrically heated glass is a laminated glass, incorporating almost invisible electrically-conductive wires. It comprises two or more sheets of glass interlaid with one or more films of polyvinyl butyral (PVB). This assembly combines comfort with safety, whilst preventing condensation. Electrically heated glass is suitable for any circumstance where there is high moisture content in the air and where the difference between the internal and external temperature may lead to condensation risk.
Production
In order to electrically heat glass, a microscopic Tin (II) Oxide coating is applied to a pane of ordinary float glass. This coating is perfectly transparent and conducts electricity. An electrical current is supplied by two busbars located on opposite sides of the glass. The electrical resistance of the Tin Oxide coating produces heat energy. This heat radiates from the glass in the form of infrared energy. The busbars are typically connected to a power control unit that regulates the flow of electricity and thus the temperature of the glass.
Electrically heated glass maintains a steady and consistent temperature across the entire surface, and heat radiates off the glass in only one direction: toward the object or area to be heated. In addition, this technology imparts beauty and elegance to glass. The glass can also be coloured or etched with designs in order to complement the appearance of a room or appliance.
Groceries
Heated glass is both visually attractive and sanitary, making it ideal for use with food in a public setting. Since the glass is perfectly transparent, deli items are in full view of the customers, and remain hot and ready to serve. Keeping meat and other food items warm improves their taste and prevents spoilage. This technology is much more efficient and effective than heat lamps, and is a definite improvement over microwaving cold food just before it is served.
Electronic Controller
An electronic controller regulates power flow to the heating components, and thus controls glass temperature. With a simple twist of the dial, the glass can assume any temperature from approximately 70oF to 350oF. An important feature of the controller is its automatic fault and glass breakage detection capability that will automatically shut down the heating circuit if there is a problem. In addition, the appliance should include a GFCI breaker to guard against ground faults and leakage currents.
Electrically heated glass windows
Electrically heated glass can also be incorporated into a double-pane Low-E architectural window unit. With the heating element applied only to the interior side, the window will radiate warmth into the room no matter what the temperature outside. This eliminates heat loss, chills, drafts, and frost problems associated with ordinary glass in cold climates. In warm weather, heated glass prevents condensation, which helps prevent mould from growing on the window sill.
Towel warmers
Electrically heated glass can also be employed in the design of towel warmers for both custom homes and hotels, replacing traditional radiator style units. The invisible thin film conductor involved in this design is even more efficient than traditional radiator-type towel warmers. These stylish towel warmers are comprised almost entirely of glass, yet the glass used in these applications is never too hot to touch, and it does not contribute noticeable amounts of heat to the room.
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