Gas Dryer Vent Size

When using a straight piece of flexible metal vent hose the maximum length allowed for safe ventilation is approximately 30 feet according to the appliance aid website.

Gas dryer vent size.

Using a vent hose that is too small presents a fire risk while one that is too large can result in inefficient drying. Let s start with what the irc international residential code says. The maximum airflow is 230 cfm. You should use only 4 inch 10 2 cm diameter minimum rigid aluminum or flexible metal duct and an approved vent hood which has a swing out damper that opens when the dryer is in operation.

Dryer vent pipes properly called vent ducts come in a variety of materials. Dryer vent hoses vary in size but most used for residential dryers are between 4 and 5 inches in diameter. Dryer vent hoses that are run in a straight line from the dryer exhaust to the outdoors provide the best ventilation and reduce the likelihood of trapped lint. The exhaust airflow of any whirlpool produced dryer at the maximum rated vent length is at least 105 cfm.

The maximum length of a straight run of dryer duct is 35 feet with a 5 foot deduction in length for each 90º bend and half that for 45º bends based on using a 4 inch smooth metal vent with no screws protruding into the air flow. Some are flexible and others are rigid. Most dryer ducts are round and 4 inches in diameter. Because all types are sold for use with dryers you would naturally assume that all are suitable for this application.