Chimney and dryer ducting

In an 1877 duplex I smelled “dryer sheet” scent when I was in the attic near a shared chimney. The chimney is not in use from the side of the building that I was on because the furnace was not functional. The chimney felt mildly warm. I am assuming that the owner of the other side of the duplex (that side is occupied) is using that chimney to vent both their furnace and their dryer. I am new to all of this. I am studying toward my license, but haven’t even read the HVAC course yet.
I am assuming that the neighbor is creating a fire hazard though by mixing the dryer vent with the furnace exhaust. Please give me your thoughts.

That assumption is most likely incorrect (I hope). It’s extremely dangerous to share a dryer vent with that of a furnace. Most likely what you smelled is either dryer exhaust entering the attic from the outside or dryer vent terminated or leaking into the attic (also very wrong).


Thank you so much. The dryer sheet smell was only near the chimney. If I moved away from the chimney the smell decreased.

People do crazy & dangerous things all the time. The only way to get to the bottom of it is to find out where and how the dryer is venting.