NO! DO NOT TIE INTO EXISTING VENTS OR DUCTING. In some cases, this is a hazardous situation. Additionally, an ember could make it through the exhaust fan of the laser and ignite any dust or particulates settled in the existing duct line. It may also give off gases from sewage vents, creosote from chimneys, fuel pooling in exhaust systems, and more. Please ensure that ALL laser exhausts remain independent from other exhausts and dust collection systems.