5+ feet. The optimal viewing distance for our fireplace is at least 4-5 feet away extended indefinitely. From this distance the fireplace will look perfect and very much like a real fire. Any closer and you might see a little bit of reflection on the bottom of the glass, but that completely disappears once you back up a few more feet.
The quality of the flames will look outstanding at any distance because it’s a video projection, and therefore will always look good, even up close as the flames are presented in high-definition.