Smoke in Basement
Hoping someone can provide us with some insight/suggestions. We've had a chimney sweep/repairman out to help and he capped the flue but had no further ideas.
50 year old home, We have a fireplace on main floor venting into a chimney that runs side by side with an old furnace flue. The old furnace was replaced and is now exterior vented through the cellar wall and the old furnace flue in the chimney has been capped. Since the new furnace was installed, there is a good deal of smoke that flows in to the basement thru the furnace cleanout every time we have a fire.
There is no smoke on the upper floors of the house. The exterior chimney is in good repair.
Could there be an air exchange between the flues inside the chimney (maybe a broken liner?) or is this likely due to an improperly capped unused flue?
Thank you for any advice you might be able to offer.