The use of the white vinyl flex pipe is all but completely prohibited, both by building departments and appliance manufacturers.
Flex lines on a dryer are not a good idea, especially on a gas one - they can and do restrict the air flow, collect lint, and pose a fire hazard. Use solid ductwork instead, and you'll shorten the drying time since the air will flow better, and help prevent lint buildup.
A friendly #PSA, every dryer manufacturer has a warning ⚠️ label that says do NOT use plastic of foil duct. They can be a potential fire hazard AND the necessarily contribute to poorer airflow. After being hung up on twice by a local appliance store for attempting to have a friendly civil conversation to simply share.
In summary, while flexible accordion piping may seem like a convenient option for dryer venting, a hard pipe provides better airflow, fire safety, durability, and aesthetics. Investing in a hard pipe may cost a bit more upfront, but the long-term benefits make it a worthwhile investment for any homeowner.
M1502.
The transition ducts are the common flexible hoses that connect the dryer to the outside vent or termination. Code M1502. 4 stipulates that these hoses be no longer than eight feet. They also cannot be enclosed within the construction of the house.
The maximum developed length of a clothes dryer exhaust duct shall not exceed 35 feet from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet for each 45-degree (0.8 rad) bend, and 5 feet for each 90-degree (1.6 rad) bend.
Rigid Metal Ducting: Rigid metal ducting, such as aluminum or galvanized steel, is widely considered the gold standard for dryer vent systems. These materials are non-combustible and can withstand high temperatures, reducing the risk of fires.
Disadvantages of Flex Duct
Flexible ducts are more prone to air leakage around the seams, which can lead to lower HVAC system performance. Additionally, the pliable nature of flex duct tends to make them prone to tangling or crushing when they pass through tight spaces or fixtures.
Vent Type and Length
Any Dryer ducting used must be UL-listed. UL now requires that all Dryers be installed with either rigid or flexible metal ducting. Rigid is preferred. A UL-listed semi-rigid Dryer duct can be used if the vent length is 8 feet or less.
Metal tape can also be used to secure the flexible aluminum duct, too, but clamps make it easier to remove the tubing for cleaning. Aluminum foil duct is inexpensive and relatively easy to work with, but its ribbed walls can trap lint, a potential fire hazard.
Route the dryer vent horizontally to the home's outside wall. Duct work should pitch 1/4-inch per foot to the outside. This keeps moisture out of the pipe. For basement laundry areas where your ductwork will run vertically to the outside wall, you may need to use 90-degree elbows.
A shorter hose provides a direct path for hot air and moisture to escape, reducing the chances of lint buildup and blockages. If your dryer hose looks a mess, call Dryer Vent Wizard today!
The exhaust duct should be rigid metal 4 inches in diameter and no more than 35 feet in length or as specified by the duct manufacturer. This length should be decreased by 2.5 feet for every 45-degree bend the duct makes and 5 feet for every 90-degree bend the duct makes.
Although dirty, this break allows heat and moisture to escape and limits your immediate risk of a dryer fire. PVC piping will not do this which leads to water pooling and severe clogs. These clogs will cause your dryer to overheat and become a potential hazard.
Some dryer vent installations also have an external lint trap, which is also known as a secondary dryer lint trap or a 4″ In-Line Dryer Lint Trap.
Dryer venting tips and practices
Flexible transition hose between the dryer and the wall outlet should be either the foil type or the aluminum flexible duct (most preferred). Do not use the plastic or vinyl. Concealed ducting must be rigid metal (galvanized or aluminum) duct.
DO NOT terminate dryer vents in crawl spaces or attics. Dryer vents that terminate in crawl spaces or attics allow for moisture to deposit and encourage mold growth and health hazards. Dryer vents must terminate outside of the building.
Never install a dryer vent which has a bend greater than 90 degrees. Sharp bends restrict airflow and will lead to excessive lint buildup.
Loud Noises: One of the first signs of flex pipe failure is a loud rumbling noise. If there's a crack in your flex joint, it will sound like you have an excessively noisy engine. The exhaust flex joint may also produce a hissing or tapping sound that gets louder the faster you go.
The longevity of HVAC flex ductwork hinges on several key factors, including material quality, installation, and maintenance. Typically, well-installed and properly maintained flex ductwork can endure for 15 to 25 years.
According to most building codes, dryer vents don't need insulation. But, it can be a good idea—especially if your laundry is located in or runs through an unheated area of your home, like a basement or crawl space.
Metal can withstand the heat generated by the dryer, and is will not accumulate dust and lint like plastic pipe. Aluminum duct is usually a safe bet, and it's fairly inexpensive. Steel is another option, though it is pricier than aluminum and PVC. Better safe than sorry when it comes to your home.