Hi, I need a nudge in the right direction.
I live in an apt complex built in the 70s that was recently flipped into condos. I had my HVAC replaced about 18 months ago. I am on the second floor of a two-story building and there is a vent that runs from the first floor HVAC closet, goes into the attic/atmosphere. There is a vent that comes out of the top of my HVAC unit and joins this main vent.
Recently, a new tenant moved in downstairs and he smokes inside. When he smokes, I can smell smoke coming from my HVAC closet. I sealed all the visible seams on the vent tubing with a putty-type of sealant and with metallic duct tape, and the smell still reoccurs.
The smell is most prevalent when I am not running my HVAC unit at all (windows open because it's a nice day, at night the temps are comfortable without HVAC assistance, etc.), so now I suspect that some sort of negative pressure is sucking the smoke through my HVAC unit into my condo.
Is this prognosis feasible? If so, what are potential solutions? What else could be going on?
Thanks in advance!