A dryer's exhaust system basically consists of a vent pipe, ducting and an external vent. Emissions from the dryer exit the pipe and travel through the ducting and finally through the external vent outside. It's extremely important that air can pass through the exhaust system without restrictions. If a clog forms in the exhaust system due to condensation and lint buildup, it can result in slow drying times and your dryer can overheat.
Signs of Condensation Buildup
If condensation builds up in the exhaust system components, it attracts lint. Once lint mixes with the moisture it forms a thick residue that limits airflow. It will likely take longer for the machine to dry clothes when airflow is hampered. Instead of running one drying cycle, you might run several to get clothes dry. The more restricted it becomes the greater chance that your dryer will overheat, since it won't be able to properly regulate the drum's air temperature.
The best way to prevent condensation buildup is to empty your dryer's lint tray after every laundry load, and clean the dryer's entire exhaust system once per year. This cuts down on the amount of condensation in the system and decreases the chance that it will combine with lint and lead to an obstruction. Clean the exhaust system more regularly if the external vent drips with condensation; this is also a sign that a blockage exists.
If you routinely find moisture in the dryer's drum or even moisture streaming from the external vent, it can indicate a problem with your dryer's venting. Make sure that the ducting isn't longer than 25 feet, and make it shorter if possible; the longer the ducting, the greater chance of condensation forming. Eliminate unnecessary bends in the ducting where condensation can develop. The ideal ducting for promoting unrestricted airflow is 4 inches in diameter, according to Don Vandervort's Home Tips website. If it's smaller than 4 inches, moisture can become trapped inside.