Question: I have been receiving (and enjoying) your e-mails for about two years now. I live in Northern New York and have a wood stove in my basement and a fireplace in my living room, both as secondary heat sources. I have a question for you that perhaps you could answer. Our fireplace is a two sided Martin fireplace with glass doors on both sides. It uses a double wall chimney. I now have approximately 20 foot of chimney and it rises a few feet above the peak of my house. My problem is that I can't seem to prevent smoke from backing up in my house when I use the fireplace. I have recently added an extra chimney section which helped some but not totally. I now believe that the problem is not the height of the chimney but something else. Would an outside air vent kit into the fireplace help?? We run our ceiling fans to produce a positive pressure in the rooms. Does this actually help?? Note: It seems to work best with the glass doors on both sides shut, however this prevents a lot heat from entering the room. I realize this fireplace is mainly for looks, however the extra heat is nice. Also, with one side opened slightly the other side will tend to draft smoke back into the room. Answer: It could be two things. 1. The chimney needs more height (you've already done some of that) 2. Not enough "make up" air (air for combustion First, I'd forget about the ceiling fans. They stir the air up, and this is not good for draft. Then try running the unit with a nearby window open. If it works well, then it's the lack of combustion air...and an outside air inlet may solve your problem. Another hint is for your fire starting technique. Follow the rules about fire starting and tending at https://www.hearth.com/what/specific.html ....making certain that you start off with a nice hot fire to get the flue warm. This can help your draft get and stay established.