Flexible plastic ducting

This material is frequently used to connect the dryer with the exterior so that warm moist air can be exhausted to the outside. It’s cheap and easy to use but I’m not a great fan of this material because the ridges can trap lint and severely restrict air flow. The photograph below shows excess plastic ducting used to connect the dryer with the exterior. It is located in a large crawlspace and the area is likely to be cold. Here’s what can happen:
• Due to the long run and changes in direction, the movement of exhaust air will be restricted. It is likely that before the air reaches the exterior, it will cool;
• The high moisture content in the air will condense and collect at the lowest point;
• The weight of the water will also pull the ducting down, making the situation worse;
• Eventually, the condensed water will totally block air flow;
• Being uninsulated in a cold or unheated crawlspace, the water could also freeze during the winter;
• The build-up of lint may also be a fire risk.
I recommended to my clients that they replace this with an insulated metal duct and have a horizontal run from the duct entrance above the white pipe to the exterior wall on the right, as shown by the arrow. This is a simple and inexpensive solution that will prevent major problems.
ducting Jan 21, 2015