"Flame blue" is an interesting color. Since that term is rarely used, it conjures up specific images. The obvious is that we are looking at blue flames on this cover art. Since everything is blue here, it doesn't automatically seem outstanding that the flames are blue. However, being told that the color is "flame blue" makes those blue flames seem significant. Could the room be blue because of those blue flames, or did the artist make everything blue to reflect the significance of blue flames? The hottest part of a flame is usually blue, and since there seems to be a definite preponderance of flames in Book 5, it may have to do with the burning process (or it may not).
We have seen blue flames already in the series. Some of them may not have much significance. For instance, the Goblet of Fire had blue-white flames, the flames that Hermione used in Book 1 to distract Snape, by setting his robes on fire, were blue, plus the fire that Hermione kept in the jam jar to warm themselves outside as Snape limped over to them, had bright blue flames.
The most closely related seem to be the candles leading to Nick's deathday party. Those candles had black tapers (rather than the white we see here), but just like those here, they had bright blue flames and were described as casting blue light on everything around them. There also was a chandelier in that dungeon, made up of candles with bright blue flames. Their description was "blazed midnight blue." Sound familiar? That is the exact color mentioned in the press release!! This definitely leads one to ponder a ghostly connection.... goto top
HP Super Sleuth Scott Graupner (iharrypotter.net) reminds us that we were told in Book 1 that we shouldn't be trusting any doors. When Harry first gets to Hogwarts, he discovers that doors aren't always what they seem, and that walls have nasty habits of pretending to be doors. So, maybe the question isn't how many doors, or what the doors are doing, but are they even really doors at all?