Anatomy of a Dryer Ventilation System

The purpose of your clothes dryer is to dry your wet clothes that have just been washed in your washing machine. To do this, the dryer applies heat (at a level of your setting, if so equipped) and moves the clothes around while creating airflow. The heat and spinning dry off the clothes, and the airflow carries the hot, wet air out of and away from the dryer.

The heating element heats up, and a fan-like device pulls air from the heating element through the dryer. Normally the heating element is at the back of the dryer - if you look, you'll see a bunch of little holes. The air is pulled through the lint screen (normally at the front of the dryer, near the door) and then out the dryer vent.

This is why you should clean your lint screen every load. If the lint screen is clogged, airflow will be recuded and drying efficacy will be reduced. But the lint screen still only captures 75% of the lint. The rest of it goes into the vent system and can be captured in there. If you take out your lint screen and look behind or under it, you will likely see a build up of lint. Some people use long lint brushes to clean this part of their dryer on a weekly basis.

At the bottom of that area behind or under the lint screen is where the fan-like device (it is actually somewhat more like a turbine - cool, huh?) pulls the air out of the dryer into the vent. Then inside the dryer is a bit of vent, which leads to an outlet from the dryer. At the back of your dryer is where the external ventilation system begins.

The vent is normally made up of a transition vent, a main vent, and a hood assembly. The transition vent goes from the dryer to the wall or floor. The main vent is hidden away from sight and leads to the outside of your residence. The hood assembly is the part that is visible from the outside. Behind the hood is a tailpipe which connects to the main vent. And there you have the path it takes.

You may notice that your transition vent seems much longer than it needs to be. This is normally done to make it easier to service the dryer, such that there's enough extra vent to be able to pull the dryer away from the wall a bit without the vent coming disconnected from the dryer. The transition vent may be made of flexible foil-like material (shown above), it could be a more rigid flexible pipe (shown to the left), it could be hard straight pipe (illustrated to the right) and elbows, or it could be some combination of these materials. White plastic should be an alarm to you, as this is not safe - it is flammable and should be replaced.

The main vent should be as rigid as possible. Since it is normally out of sight at best and inaccessible at worst, you want it to be foolproof. Whenever possible, it should be all hard straight pipe and elbows. Sometimes hard flexible pipe is needed. Soft flexible foil should be avoided if at all possible.

The tailpipe will almost always be a hard straight pipe segment connected to the hood. The hood may be a full-sized four-inch hood, a compact two-inch hood (not recommended), or a low profile hood (that's the one with three or four flaps but no real hood). This generally closes while the dryer is not running and opens when it is running. This keeps unwanted visitors (e.g. birds) out but allows proper airflow when needed.

This overview of the parts of the dryer ventilation system is the basis of knowledge needed to properly service a dryer ventilation system. Next time, I'll explain how to clean the inside of the dryer.