When we purchased our dryer at The Brick, they couldn't (or wouldn't?) install so we called an appliance installer who used that coil type tubing to connect the dryer to the external vent. In very little time, the dryer just wasn't efficient anymore. We called the Wizard! They replaced the coil with solid tubing, cleaned out the vent at both ends (at the dryer and at the outside wall, put in a new exterior vent and gave us some really good advice to boot! That was about 2 years ago and we've had no issues since... but it's probably time to consider having them inspect and clean it again just to be proactive. We have no doubt that it will be money well spent.