Look at your water heater vent pipe. About 3 inch diameter, maybe 4?
Then look at your chimney. How big is it?
When you send vent gases out, you have to replace that air with air that
comes INTO the house. The water heater has an opening of maybe 12
square inches, the chimney has a lot more. So it has to pull air in from
around doors and windows to supply the draft for the smoke to go out the
chimney. If you've got a 'tight' house, that air won't be sufficient for the
chimney, and the fireplace won't be able to send the smoke up the chimney.
So where can it go, but into the room?
There are often openings for air to be pulled into the firebox area, to
supply
combustion air. Either you don't have them, or don't know about their
presence.
I suggest that you learn more about building a fire inside a house before
you
do it again. And remember that the utility companies see a fireplace as a
net
heat loss area. Especially if you forget to close the damper. You do know
about the damper, don't you? Don't answer that.

Dustin -o-m wrote in message
...

When I light up the fireplace, the room is filling up with smoke.
I've checked the flue and it's definitely opened as far as it can go.
What I'm wondering is, is it possible that the chimney, or the pipe
leading up to the roof, is partially clogged? I've heard others
mention too that it could be due to the air flow outside, causing the
smoke to drift inside the house.

Also, the fireplace has what appear to be transparent doors on it (I'm
guessing they're glass, but not sure). Is it safe to close these
doors while the fireplace is lit? I just didn't want pressure to
build up or something weird to happen.

If the chimney/flue/pipe (whatever it's technical name is) is clogged,
what are the solutions? I've heard something about special logs you
can get for the fireplace that help clean out the pipe, do these help?
What do I need to repair this?

Thanks,
Dustin