As stated above, the crew performed professionally however since the suction hose (large wide tube) was routed through the garage door for the shortest distance to the furnace and when the vacuum ran a huge draft into the house occurred from the open door. The truck's diesel engine ran for over an hour and fumes poured into the hours through the garage! I had to jery rig a barrier of plastic bags and duct tape around the open door to keep from becoming overcome by truck fumes! I also opened the patio door to provide fresh air, the crew said "that can't hurt.." Your crew closed my garage door onto the tube but fumes still came in..they said they'd work fast...I can't believe this is a safe way of "cleaning" air ducts and recommend a review of your venting procedures for customer safety..
Alan White