Which type of clothes dryers are exempt from the general exhaust requirements?

Condensing (ductless) dryers are exempt from the general exhaust requirements because they operate differently than traditional dryers. These dryers use a condensation process to remove moisture from clothes, collecting the water in a reservoir or directing it to a drain, rather than expelling hot, moist air through a vent. As a result, they do not require an exhaust duct to vent air to the outside, which is a key feature of standard ducted dryers and gasoline-powered dryers. This lack of ducting means these units do not contribute to the same ventilation and exhaust concerns that typical vented dryers do, thereby making them exempt from the associated exhaust requirements in building codes.

Electric dryers, standard ducted dryers, and gas dryers typically rely on ventilation to expel the moisture-laden air outside, which is why they must adhere to the general exhaust requirements outlined in the mechanical codes.