Roof Venting

For dryer efficiency and safety, the shortest and straightest ducting route is always best. Every turn increases friction loss (unless you use non-restrictive elbows). Air velocity reduction from friction loss promotes lint build up and makes the dryer work harder to completely dry each load. Length of run also reduces efficiency. The longer the run, the more friction loss is created which is why building code restricts total run length. Often, going straight up through the roof is the shortest route.

While elbows and length-of-run are important factors for efficiency and safety, the exhaust termination is often the biggest restriction point. The DryerJack®, in fact, was born of extensive testing of the Dryerbox and Dryer-ell and how they improve airflow. In real-world tests, inefficient roof terminations would often all but negate the improved efficiency of eliminating restrictive elbows. While it sometimes made sense to vent through the roof, every roof vent that had previously been used was inefficient (often to a dangerous degree). In order to take advantage of the shortest route, a better termination was required

Roof Vent Airflow Restriction for Non-Dryer Specific Vents

Problem Roof Vents
WCI Airflow Reduction	.35	.30	.45

Versus the More Efficient DryerJack™

DryerJack 477 Low Profile and Efficient

A Better Roof Termination

DryerJacks are the first roof vents designed to meet the more stringent venting requirements of dryer exhaust systems. Unlike the vents shown above-left, the DryerJack is dramatically more airflow efficient.

Considering that back pressure higher than .6 WCI is generally recognized as inefficient, you can see that venting through the roof with non-dryer specific vents is immediately problematic. The less back pressure is created by the roof vent, the more efficiently the system performs.