Abstract: A multiple-pane, hermetically-sealed, thermal-resistant window with a spacer between adjacent panes for maintaining separation between the panes wherein the corners of the spacer are rigidified and locked by a corner insert which prevents separation of adjacent spacer frame members and wherein the spacer frame members are attached to the window frame to prevent and/or reduce movement of the spacer frame members. The seal around the cavity between adjacent panes is completed after the temperature of the window components and the cavity air is about equal to the temperature of the ambient air. A resistance heating wire is applied to the outside surface of the spacer frame intermediate the adjacent panes of glass.

Abstract: A multiple-pane, hermetically-sealed, thermal-resistant window unit is disclosed having a spacer between adjacent panes for maintaining separation between the panes, wherein the corners of the spacer are rigidified and locked by a corner insert which prevents separation of adjacent spacer frame members and wherein the spacer frame members are attached to the window frame to prevent and/or reduce movement of the spacer frame members. The seal around the cavity between adjacent panes is completed after the temperature of the window components and the cavity air is about equal to the temperature of the ambient air. A resistance heating wire is applied to the outside surface of the spacer frame intermediate the adjacent panes of glass.