QUESTION: I have a conentional fireplace with a glass door. When burning the fireplace requires that a window or door be left open for draft.
I want to provide combustion air by creating an opening to the outside through the back of the chimney. The combustion air could come up from the bottom, or back of firebox.
Is there any reason not to do this?
ANSWER: there was a time it was code to have the "make up air vents" in fireplaces but they fond it was not enough with only 1-4" vent. The problem is your house is venting air out "house stack effect" stop the air from getting out (other open fireplaces, attic doors, vent, leaky windows...etc) the smoking will be much less or stop all together. you may still need to open a window to start your fire and close it after it is going....nature of the beast.
---------- FOLLOW-UP ----------
QUESTION: Just want to clarify.
A 4" or better combustion are vent inside the fireplace is a good idea but may not solve the problem completely.
How about an extra large combustion air source from inside the firplace (direct from outside) and a glass door that provides a perfect seal (like a wood stove door)?
Our house is almost air tight during the winter when all doors and windows are closed. I want to ensure the fire can burn hot without creating excess (uncontrolled) drafts.
Welcome back Brian, they do not make "glass door that provides a perfect seal (like a wood stove door)" you might do better installing a fireplace insert, most have 6" smoke pipe and draft can be controlled by draft controls, might only have to open a door/window to start and add wood, I am not a big fan of making holes in a fireplace for make up air. As far as your house being air tight I do not think so if you are having such a hard time with smoking, I would check with a lit piece of incense every door, window, light in the ceiling, bathroom/kitchen vent and see it it is moving air, be careful.