So you’ve got a two or more level house, with fireplaces on each level connected by the same chimney flue. Older homes are usually where this situation can be found. A system such as this can cause many problems, including a smoking issue that can be very difficult to fix. Smoking problems that arise from a chimney system such as this, where two fireplaces are venting through the same chimney, can cause smoking problems on any level of the home due to lack of air on the level which the fire is burning.
Say you have a fire in the fireplace in your living room and your kids in the basement start yelling that smoke is coming out of the fireplace down there. This is a classic example of lack of air for combustion on the top floor. Older homes were originally built without much regard to the amount of air available for combustion because older homes were much more drafty. Small gaps around the windows and doors and generally less sound construction allowed more air to enter the home to replace the air being used up for combustion.
If your older home has been fitted with new windows or doors which are more air tight than the old ones, you have a higher likelihood of experiencing a smoking problem. The solution to this problem is generally not difficult, but does require professional assistance. The bottom line is that the fireplaces on each floor of the home need to have adequate air for burning, and that needs to
be done in any way possible. An outside air source installation is generally inexpensive and non obtrusive. It involves removing a brick or two from the outside of the chimney and a brick or two from the firebox itself to install a vent, which can be opened and closed as needed, to provide the fireplace on that level with air.
Basement fireplaces, however, may not be situated on the home such that a vent can be installed. Only if the back of the chimney can be seen on the outside of the home is this possible. Chimney professionals have come up with ways to facilitate air into a basement which involves running a pipe down into the basement to provide outside air to the entire basement. You will need to discuss this option with a chimney professional.