types of dryer ductwork explained by experienced local HVAC pro

5 Types of Dryer Vent Hoses and How to Choose One

Dryer Vent Hoses Allow Clothes Dryers to Exhaust Moist Air outward while drying freshly washed clothes. You can purchase dryer vent hoses (also called dryer ducts) in a variety of materials, some flexible, some rigid. Most dryer vent pipes are round and 4 inches in diameter. As all types are sold for use with dryers, it is natural to assume that they are all suitable for this application.1 Unfortunately, this is not the case.

Local building codes generally do not allow vinyl/plastic breathers and some regulations prohibit any form of flexible breather. Additionally, clothes dryers may come with manufacturer specifications for the hoses to be used with a particular model.

Below we analyze the five common dryer vent pipe materials used to install a dryer vent and the factors to consider when deciding which is the best solution for a new appliance. or to replace existing pipe to be machined Not suitable for entire conduit; may not be permitted by some codes; can trap lint

Semi-rigid aluminum Economical, easy to work with Can trap lint; may not be allowed by some building regulations

Thin duct Excellent for limited spaces A bit pricey; complicated installation

Rigid metal More efficient type, long life A little expensive; installation can be complicated

Plastic/vinyl Very inexpensive Not allowed by code due to potential hazard

01 of 05

Aluminum Duct

Flexible Aluminum Air Duct

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Best for: transition ducts in exposed locations.

Made of flexible aluminum foil with an integrated spiral wire for reinforcement, this type of duct is suitable for transitioning from the appliance to the main rigid duct that goes to the ventilation hood outlet external.

Generally, it should not be used for the entire length of conduit.

The aluminum duct can fit an accordion from about 1 to 8 feet, which is usually sufficient for most installations. Double check to make sure this type is approved for your dryer model and allowed by local code. Transition ducts should not be hidden in walls or other building cavities and generally have a maximum allowable length of eight feet. The film duct is held in place with dryer clips or large hose clamps.

Metal tape can also be used to secure flexible aluminum conduit, but the clips make it easier to remove the tubing for cleaning.

Aluminum foil duct is inexpensive and relatively easy to use, but has ribbed walls that can trap lint, causing potential fire hazards. Best used for relatively short sections to join the dryer outlet to the main vent.

Tip

The best way to ensure that a conduit is safe for your installation is to look for a product listed or certified by a national testing laboratory such as UL (Underwriters Laboratories). Building codes often specify "listed" or "L and L" (listed and labeled) conduit for all new installations.

02 of 05

Semi-Rigid Metal Duct

Dryer Duct

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Ideal for: Transition ductwork in exposed areas.

> Semi-rigid metal conduit pipe (usually aluminum) is flexible and similar to aluminum pipe but a bit stiffer. Like aluminum tubing, semi-rigid tubing should only be used for transition ductwork from the dryer outlet to the main duct and cannot be concealed in walls or floors. It is usually installed with pliers, which makes it easy to remove for cleaning. Semi-rigid metal ducts are often stronger and have a smoother interior (takes less lint) than aluminum ducts.

Semi-rigid metal conduit is also relatively inexpensive. Although it is sometimes used for an entire exposed duct, such use is debatable. This type of duct tubing has an internal corrugation and therefore tends to trap some lint. Semi-rigid tubing should be used for the entire duct run from the dryer outlet to the vent hood, only if the duct is fairly short and straight (less than 8 feet), only if it is exposed rather only hidden, and only if local code permits such use.2

Tip

If you are using flexible tubing, cut it to the shortest length needed to transition between the outlet of the dryer and the rigid duct or vent hood outlet.

This minimizes flexing or sag, making the hose less likely to trap lint.

03 of 05

Thin Conduit

Best for: Running conduit where space is limited.

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Thin duct, sometimes called periscopic duct, is a rigid aluminum telescopic tube used to make transition ducts in confined spaces. It has a wide rectangular shape except for the two ends where it connects to the dryer and the vent outlet, which have round necks. It allows the dryer to be pushed very close to the wall.

It can be a great space saver as long as the dryer and the extractor hood are close together. Most slim ducts can be adjusted from about 27 inches to about 48 inches in length. It is also adaptable to vertical, horizontal and diagonal installations.

Thin ducts are a bit more expensive, but offer a good option when distance between walls is an issue. They can be somewhat difficult to install and are sometimes used in conjunction with short-lived semi-rigid pipes for transitions.

04 of 05

Rigid Metal Duct

Rigid Metal Duct

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Ideal for: any dryer vent application, concealed or exposed.

Rigid metal conduit is the only material suitable for concealed conduit installations, that is, conduit that passes inside walls, floors, or other enclosed spaces. Available in aluminum and galvanized steel, rigid metal duct is very smooth on the inside, so air flows with little friction and picks up the least lint of any duct material.

Rigid metal duct is more expensive than other types, but is extremely durable and efficient.

And building codes generally allow lengths of up to 35 feet, compared to a maximum of 8 feet for transition pipes. Adjustable metal elbows, even with smooth walls, can be used to make the passages between the rigid vent and the dryer outlet at one end and the hood at the other end. This type of configuration, with a smooth-walled vent running from the dryer to the hood outlet, allows for optimal installation. However, working with rigid metal ductwork and adjustable collars can be a bit tricky, which is why some homeowners will choose to have the installation done by a professional.

Warning

Always use metal tape to secure joints; do not use screws, as they can catch lint.

Do not use regular plastic tape as it will dry out and deteriorate.

05 of 05

Plastic or Vinyl Duct

Plastic Dryer Duct

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Best for: Do not use. Vinyl plastic ductwork is not permitted by most building regulations.

Flexible plastic (usually vinyl) ducts are similar to aluminum foil ducts, but have a thin plastic wall instead of metal foil.

Despite its popular use for many years, plastic conduit is no longer permitted by most building regulations. The grooved interior of the flexible duct traps lint easily.

Warning

If the duct becomes clogged with lint, it can become very hot and potentially catch fire.3 This hazard has caused many home fires. Plastic conduit is the least secure option and you will not find a UL Listed product made from this material.

The bottom line: don't use it.

Choosing your dryer vent hose

There are several types of dryer vent hoses, but some are better than others and some should be avoided due to problems with security possible. The dryer vent pipe is not a very expensive material, so there is little point in saving money by "buying cheap". Instead, be sure to follow local code guidelines for installation. Some basic guidelines for choosing:

In general, it is best to choose rigid metal tubing for as much of the duct as possible, as this type provides the best air volume and few obstructions internal to capture flammable lint.

Thin metal conduit is the best choice when distance between walls is an issue. It also has smooth walls that don't trap lint, although the air volume may be slightly less than a tubular metal duct.

Semi-flexible metal duct is a good choice for transition ducting from the 'rigid dryer' outlet to metal duct because it can be bent to form fairly smooth bends and bends. But even then, a better choice would be adjustable rigid metal elbows with perfectly smooth walls.

The worst choices (and usually an illegal choice) are flexible vinyl or plastic ducting and aluminum ducting. /p>

Both tend to trap lint, and plastic ductwork can melt easily if the heat buildup gets too much.

Tip

It is advisable to get into the habit of cleaning Ventilate the dryer regularly: annual cleaning is preferable. There are a variety of inexpensive accessories that allow you to brush the inside of dryer vents and vacuum them without trapped lint.

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