Help with Shared Chimney

[mncomic]

I have a 1950's home with a fireplace upstairs and one downstairs. The one upstairs is the only functional one
but when I use it I get smoke downstairs. Any advice on how to eliminate or reduce this? Thanks

 

[begreen]

Odds are that both flues terminate at the same height at the chimney top. This can lead to siphoning from one into the other, especially if the basement is a negative pressure zone. If this is the case, the solution is to put an extension on the upstairs flue to raise it 12-18" above the basement flue. They also make chimney flue balloons that can be inflated into the downstairs flue to block it off.

Do a google search for chimney flue extension or extender or stretcher. Here is one example:

Chimney Flue Extender | Specialty Flue Extension with Designer Lid - Rockford Chimney

The Specialty Flue Extension with Designer Lid increases the height and draft of your chimney flue. Reduces risk of smoke being drawn into the flue.

www.rockfordchimneysupply.com