These improvements relate to the normal advancements, innovations and improvements discovered during the almost three-year period the patent application was winding its way through the examination process. In few words these discoveries center around a mechanical design modification to the bifold glass door closure area, and a film-grid panel design modification for soot and creosote control.
The usual presentation of any fireplace when using wood for heating a room is to provide a sufficient source of heat for warming purposes. When a fireplace has glass door protection, little heat is emitted because the glass doors tend to prevent the infra-red heat waves from passing out through the combustion area glass doors. Heat waves will not willingly pass through glass of any sort. Opening the glass doors will give a “blast” of heat momentarily if opened, but nearly all the heat generated is immediately “lost” up the flue.
Heat loss up the flue is not easily controlled where flames are concerned with the damper “after the fire”. There is better heat regulation with damper control “before the fire”. Residual heat from glowing coals, or glowing charcoal embers is a steady source of infra-red heat waves and continues radiation for a much longer time. This form of infra-red heat easily passes through the Enigma Panel, hence the ideal use of the Enigma Panel design. Similarly, infrared heat radiation through the grate heats the discharge ends of the tubing into the attending room with less problem of heat loss.
The Applicant has tested several experimental designs in order to solve this problem of trying to get good quantities of radiant ‘infrared’ energy waves to pass undistorted through glass panes, for example, modern day fireplace combustor tempered-glass doors. The answer is not to use glass of any sort. Infrared heat waves become distorted and cannot pass freely through glass. However, all the popular fireplace insert makers continue to use thick tempered-glass commonly in all their beautiful fireplace brochures. Glass is a “killer” to radiant infrared heat waves. Quite by accident thin film was tried as a reasonable test door and for a fireplace. It was an acceptable success except for plastic memory and flame damage. Trials using mil-thick transparent film and a metal support grid in close contact can give suitable results until industry can devise a better heat-tolerant transparent plastic panel. The metal support grid is necessary to support the plastic panel (when used together “in-service”) and prevents the softened plastic from being sucked in toward the flame and damaged. The metal grid also acts as a “heat sink” and prevents the plastic from taking a permanent “set” (stretch) when it cools down.
The Applicant has been taking experimental approaches to solve this problem of trying to get good quantities of radiant ‘infrared’ energy to pass through the glass panes of modern day fireplace heat-tempered glass doors. The obvious answer is not using glass of any sort because infrared heat waves cannot pass freely through glass, yet all the popular fireplace insert makers use thick tempered glass commonly in all their beautiful fireplace brochures. Infrared heat is strong and powerful by itself, but when it tries to pass through glass it loses its energy, in other words glass is a “killer” to radiant infrared heat waves. Quite by accident thin film was tried as a reasonable test door and for a fireplace it was an acceptable success except for plastic memory and flame damage. Trials using mil-thick transparent film and a metal support grid in close contact give suitable results until industry can devise a better heat-tolerant transparent plastic panel. Until then the best heat pass-through is the “film grid” combination or “Enigma Panel”.
This sub-spec contains no new matter. This application started out as a Continuation-In-Part to: “Residential Fireplace Insert System”, (U.S. Pat. No. 7,509,954), now a separate patent application for the Enigma Panel.