We just moved into a new-to-us home. It is 20 years old. Our dryer was not working properly and the appliance repair tech said our vent was clogged. I called Pureair to check it out. When Joe came, it was not only dirty, it was totally clogged. They vacuum, sprayed, brushed and vacuumed some more. When they left, an hour or so later, the vent line was clean and the drier should work well and, most importantly, be safe.