Every year, according to the National Fire Protection Agency (NFPA), there are more than 14,000 dryer fires reported. The importance of properly configured and maintained dryers and dryer exhaust systems can hardly be overstated. And what about efficiency? Problems with dryer exhausts can lead to increased drying times, that wastes energy and increased wear and tear on the appliance and clothes. Efficient, well designed exhaust systems can let the dryer work at peak operating levels.
Dryer vent pipes, properly called vent ducts, come in a variety of materials. Most dryer ducts are round and four inches in diameter. Some are flexible and others are rigid. Since all types are sold for use with dryers, you would naturally assume that all are suitable for this application. Unfortunately, that is not the case. Vinyl duct, and in some situations, all flexible duct, is not allowed by building codes. Also, dryers may come with the manufacturer’s specifications for ducting to use with a particular model.
Warning
If the duct becomes blocked with lint, the duct can become very hot and potentially catch fire. This hazard has resulted in numerous house fires. Plastic duct is the least-safe option, and you will not find a listed product made of this material. The bottom line is, don't use it.
Now is the time to look behind the dryer. The first thing to keep an eye out for is plastic. If there is a plastic connector or plastic transition hose. It is a fire hazard, and should be replaced. There are some dangerous "slinky foil" transition hoses that might look like UL 2158A listed transition hose, but they are not. A UL 2158A can be adjusted, but it takes some work to move it around. Slinky foil just flips around and is well... slinky. Check for lint leaking out of the dryer or around the dryer transition hose. Lint blow back into the heating element can create a very dangerous situation.
Warning
Always use metal duct tape to secure the joints; don't use screws, because they catch lint. Do not use regular plastic duct tape because it dries out and deteriorates.
Duct length can also be an issue. In some cases, it can be obvious that the exhaust system only runs a few feet to get from the back of the dryer to the exterior of the building. A rule of thumb is shorter is better. Even straight pipe creates airflow resistance, and a long run can prevent lint from escaping. If a run is to long (35 feet or more) or has a lot of turns (elbows) it may be time to consider a re route of the dryer venting.
Understanding the exit port. You'd be surprised how many vents, have screens, are too small of an exit port, have no damper. All of these are prohibited by building codes for venting a dryer and need to be replaced. Surprisingly, a bad termination can be responsible for 90% or more of air flow restriction.
How often should you clean your dryer and exhaust system? One of the key things to consider when determining the frequency with which to clean your vent is how often the dryer is used. If you only dry four or five loads of laundry per week, an annual cleaning should suffice. However, if you have an exceptionally large family and dry as many as four or five loads a day, it may be a good idea to clean your dryer vent once every six months or, if you want to be extra cautious, once every three months.It is always a good idea to keep an eye out for problems with your dryer and to check for any clogs or issues with your vent between cleanings.
Failure to regularly clean dryer vents will increase drying time and, in turn, increase the cost of your utility bills. Furthermore, as dryer lint is highly flammable, the hot temperatures caused by a plugged-up vent's lack of sufficient air flow are liable to give way to large fires. In fact, dryers with clogged vents or lint screens are one of the most frequent causes of in-home fires. Also, when a dryer vent is blocked, carbon monoxide will be forced out inside your home. So in addition to saving you money, regular vent cleaning just may save your life.