Safety re: closing glass doors in fireplace

[pcampbell]

Is it safe to close the glass doors in the fireplace when the embers are red (with the flue still open) to go to bed.

I have noticed sometimes I do this and a flame actually comes back after closing the glass doors. There is no outside combustion air source for this fireplace that I am aware of.

 

[dougand3]

Yes, close them. Be safer - a hot ember can't pop thru screen. And you'll lose less house heat up the flue as fire dies. A flame pops up because combustion "box" gets hotter by trapping some heat and you're decreasing wide open intake air somewhat.