Can you use aluminum flex duct for a dryer exhaust line

[pknox (Phil Knox)]

Can someone provide the code where aluminum flex duct is allowed or not allowed for an electric dryer, or does it have to be metal?

Thanks in advance

[jjonas (Jeffrey Jonas)]

@pknox

…aluminum flex duct is allowed or not allowed for an electric dryer, or does it have to be metal?

Last time I checked, Aluminum IS a metal.

[dwigger (David Wigger, CMI, Retired)]

@pknox

aluminum flex duct

There are many varieties of that. More specific?

[rmayo (Randy Mayo, P.E.)]

M1502.4.1 Material and size. Dryer exhaust ducts must have smooth interior surfaces and be made from metal that is at least 0.0157 inches thick (28-gauge minimum). The duct diameter must be 4 inches nominal.

Purpose: The smooth interior finish requirement ensures unobstructed airflow. Corrugated interior surfaces or protruding screws create turbulence that disrupts airflow and provides places for lint to accumulate inside the pipe, which can reduce efficiency and create fire hazards.

[kleonard (Kevin Leonard, CPI/CMI)]

The cheap mylar stuff I call out everytime as a potential fire hazard, same goes for plastic. If you want to use a flex duct, make sure it’s a semi-ridgid aluminum duct.

There are approxametly 15,000 dryer fires a year.

Here’s another thread on the subject. Flue Metal vs Mylar Dryer Vent Pipe - Specific Inspection Topics / Interior Inspections - InterNACHI®️ Forum

[lkage (Larry Kage, CMI)]

The smooth interior surfaced dryer vent ducting is different than the dryer transition duct.

The latter may be less smooth on the inside for the short distance from the dryer to the wall connection.

[ryoung7 (ROBERT YOUNG, CMI)]

Afternoon, Phil. Hope to find you well.

Are you referring to clothes dryer, electric, transition ducts or flexible hoses that connect the dryer to the outside vent or termination?

[lhenderson2 (Lon Henderson, CMI)]

Shouldn’t Randy get the “Solved” designation?

[sfetty (Dave Fetty, CMI)]

The OP is rather vague here is the FBC for dryer transition duct.

M1502.4.3 Transition duct.

Transition ducts used to connect the dryer to the exhaust duct system shall be a single length that is listed and labeled in accordance with UL 2158A. Transition ducts shall be not greater than 8 feet (2438 mm) in length. Transition ducts shall not be concealed within construction.

[lkage (Larry Kage, CMI)]

@pknox

Can someone provide the code where aluminum flex duct is allowed or not allowed for an electric dryer, or does it have to be metal?.

@rmayo

M1502.4.1 Material and size. Dryer exhaust ducts must have smooth interior surfaces and be made from metal that is at least 0.0157 inches thick (28-gauge minimum). The duct diameter must be 4 inches nominal.

Purpose: The smooth interior finish requirement ensures unobstructed airflow. Corrugated interior surfaces or protruding screws create turbulence that disrupts airflow and provides places for lint to accumulate inside the pipe, which can reduce efficiency and create fire hazards

@lhenderson2

Shouldn’t Randy get the “Solved” designation?

[rmayo (Randy Mayo, P.E.)]

M1502.4.2 Duct installation. Exhaust ducts shall be supported at intervals not to exceed 12 feet and shall be secured in place. The insert end of the duct shall extend into the adjoining duct or fitting in the direction of airflow. Exhaust duct joints shall be sealed in accordance with Section M1601.4.1 and shall be mechanically fastened. Ducts shall not be joined with screws or similar fasteners that protrude more than 1/8 inch (3.2 mm) into the inside of the duct. Where dryer exhaust ducts are enclosed in wall or ceiling cavities, such cavities shall allow the installation of the duct without deformation.

M1502.4.3 Transition duct. Transition ducts used to connect the dryer to the exhaust duct system shall be a single length that is listed and labeled in accordance with UL 2158A. Transition ducts shall be not greater than 8 feet in length. Transition ducts shall not be concealed within construction.