Many furnaces are also equipped with glass doors that are especially necessary when the fireplace is warming up and can not deal with smoke and thus lets the bitter smell in the room. The glass cover helps to prevent it. The doors can be swinging or lifting. By the way, furnaces with a fireproof door are safer than open grates, and allow you to manage the flow of warm air much better and easier. The only drawback is that sometimes the heat-proof glass may be covered with soot.
The modern gas fireplaces is truly a beautiful thing, the ultimate marriage of efficient functionality and elegant beauty. They are not like the old gas fireplaces, with their meek blue flames and their obscured tempered glass door panels that trapped in what little heat there was. These contemporary fireplaces feature real-looking yellow and orange flames curling around real-looking ceramic "logs," which are very visible through newer-style ceramic glass door panels, which also let the heat pass through to the rest of the room or outdoor space. A newer model gas fireplace has more cool accessories than the old gas fireplaces - child safety screens and pull screens, storage cabinets, mantles and display shelves, ornamental ceramic logs, overlay doors and louvers, decorative panels and all-purpose grills. They can be made of anything from cast iron or stainless steel to molded cement, or even bronze, with ceramic, stone or copper garnishes.