Watch the video on Installing Dryer Vents to Code.
The laundry room is one of three areas in a home—the other two being the kitchen and bathroom—where a mechanical contractor installs exhaust vents. In the laundry area, an exhaust duct running to the exterior is installed to remove heat and moisture from the clothes dryer. If the dryer is fueled with propane or natural gas, the exhaust vent also removes combustion gases.
Removing moisture from the home is one critical function of exhaust vents. Moisture must be exhausted from the laundry area to protect interior finishes, drywall, lumber, and other sensitive building materials. Also, the clothes dryer can start lint fires, so removing heat as well as moisture from the dryer is very important.
Here are a few guidelines for ensuring that a dryer vent is installed to code requirements.
Codes typically require that the dryer duct be no more than 25 feet long. It should be 2.5 feet shorter than 25 feet for every 45-degree bend and 5 feet shorter for every 90-degree bend. If the duct is more than 25 feet in length, the system requires a booster fan or a high-output dryer. Ducts should be smooth metal with a minimum diameter of 4". Flexible ducts shouldn't be used, since they collect more lint and can easily be crushed, impeding airflow and potentially starting lint fires. The ducts shouldn't have screws or connectors, which could collect lint, blocking the flow of combustion gases. Backdrafting can occur if the ducts are blocked, sending harmful carbon monoxide back into the home.
The male ends of the duct should face the direction of the airflow. The duct exhaust must not mix with or pass through other systems, such as the return-air plenum, because heat, moisture, and combustion gases could mix with the conditioned air in the home.
The dryer exhaust duct should vent to the outside, and the vent should be at least 3 feet from any other opening. The vent should also have a termination cap and damper to keep vermin out of the home. There shouldn't be a screen over the opening, since it would trap lint and possibly cause a fire.
To learn more about installing dryer vents to code, visit:
www.buildiq.com
www.codecheck.com
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