Hiya,
Our 9 story co-op has two units per floor all which have bathrooms with forced air vents that lead to a fan on the roof. One apartment's second floor bathrooms don't vent properly. The other second floor bathrooms do. All of the vents above that level are fine. We cannot find an HVAC firm that will come in with a flexible camera to tell us if there is a tear or clog in the duct work. Ripping up the stack where that duct is located means ripping through some very expensive renovations. The apartment directly above the bad fan has open walls now. We've had two HVAC firms come through, neither one could do the job once they arrived. Can anyone suggest any vendors? Thanks!