How to install hot glass

Thermique insulating glass units from Engineered Glass Products of Chicago transforms an ordinary double-pane window into a source of radiant heat. The glass becomes the heating element. Saint-Gobain of France is working on a similar product, but company officials report that it is not ready yet  for the North American market.

Installing Thermique windows requires a trained glazier to set the insulating glass unit and route the electrical leads correctly into the window frame, and a licensed electrician to terminate the electrical wiring connections.

First, inspect the unit and associated wire connections for any damage from shipping. Any visual evidence of damage to the buss, electrical lead solder connections or wiring may render the units unsuitable for installation.

Note that the Thermique unit has two labels specifying the “up” side and the “in” side. The assembly must be properly oriented to function as designed. Correctly installed, Thermique heated glass can help eliminate drafts, cold spots, condensation and heat loss.
Thermique achieves uniform heating across an entire pane of tempered glass, typically on the inside lite of a dual IG unit, through the use of a proprietary thin-film conductor and patented electrical connections. Each Thermique window assembly must be treated in accordance with the Glass Association of North America’s Glazing Guidelines, available at www.glasswebsite.com, or those from a similar nationally recognized IG accreditation organization for tempered glass. The only variations from standard procedure involve the wiring.

Since all tempered glass is fragile along the edges, it must be stored in a vertical position on setting blocks or a wood surface if the unit is not already assembled in an IG frame. An uneven resting surface is likely to damage the glass. Even particulates, such as sand and dirt trapped under the tempered edge, can cause the glass to break under its own weight.

Before installing the Thermique heated IG unit, a qualified technician must verify the terminal resistance integrity by attaching a digital volt meter to the two lead wires. The appropriate Ohms-resistance value for the unit will be included in each IG unit’s documentation for validation of the unit’s integrity and electrical characteristics.

Again, please note that the Thermique unit should be glazed according to accepted national guidelines.

If the unit is being installed into a metal frame, the lead wires must be fed into the electrical metallic tubing or conduit. If wires are dressed through drilled holes in metal frames, they must be protected against abrasion. Metallic framing elements must have ground continuity, either in the form of a third “green” wire to a good earth ground or a metallic conduit connection that is appropriately grounded. It is the responsibility of the on-site electrician to ensure the installation conforms to all federal and local codes. In the case of wooden or vinyl frames, grounding is not a consideration.

When threading the wire leads from the glass, take care not to use unnecessary force that could damage the wire connection to the buss bars inside the heated IG unit. Wires should not be used as pull points or have any stress applied to them. It is extremely important throughout the installation process not to strain, crimp or otherwise damage or put stress on the wires or buss bars. Additionally, wires should not be run in the sill weep channel to avoid immersion in water.

Once the lead wires have been threaded through the frame openings—and through conduit if required by local building codes—to an electrical junction box where the controller will be mounted, a certified electrician should check the wire-to-wire resistance to ensure that the circuit is still intact. Also, check the resistance from each wire to ground—it should be infinite or open—to ensure that the wires did not get shorted out.

The wires should be connected to the terminals of the designated controller per the supplied wiring diagram. Thermique heated window units should never be directly connected to 120 V power. They must be connected to the correct model Thermique electrical controller—available from EGP or a licensed dealer—matched to the specific unit size. Power must be off during the attachment.

Next, attach the wires leading back to the power supply panel and circuit breakers from the controller. Service feeds, and all associated circuits, must be protected by ground fault circuit interrupter breakers. It is the responsibility of the licensed electrician to conform to all industry recognized procedures as well as codes.

The circuit breaker, with an amperage size determined by the window size, can now be enabled to provide power to the controller. Check the voltage to be certain it is within industry values. Adjustments can be made to the controller to keep the glass temperature between 70 and 95 degrees Fahrenheit.

Once installed, a heated window is indistinguishable from ordinary glass, the technology silent and invisible. The glass remains transparent with no exposed wires, discoloration or distortion. Even the framing materials are identical to traditional windows.