Question: A GREAT WEBSITE question..I recently moved into a new home with one of those prefab fireplaces. I am having trouble getting the chimney to draft properly. I did install glass doors and restricting air to the fire until the fire is established helped a lot. After a good hot bed is established the chimney drafts well. My question is how high should a chimney be in reference to the room it is drafting out of to be effective assuming no other problems. We have a high ceiling 18ft and a chimney about 17Ft. A friend of mine said he thought the chimney had to be higher the room it was drafting out of for proper drafting. Looking for any suggestions you may have...Thanks Allen Answer: Interesting question. I never thought of chimney height in relation to the roon it is in because the chimney, in order to meet minimum height requirements, usually has to extend quite a few feet about the height of the room. Maybe your room has a low ceiling in one end (with the fireplace) and then slopes upwards toward the other end.In most cases, I don't think this would make a big difference. However, a tall room can have it's own "stack effect" meaning that air rises within it. This could cause a negative pressure at the fireplace which would hurt the draft.Outside air for combustion at the fireplace would help with this problem. Most pre-fabs have this as an option. Also, opening a window nearby when you start the fire should help. Your chimney height of 17 feet is on the low end, but certainly sufficient.