Dryer Vents and Dryer Venting Basic Guide

How a Dryer Vent Works

Clothes dryers function by tumbling wet clothing through heated air in a rotating drum. This heated air evaporates the moisture, picks it up, and with a fan, pushes it out of the dryer.

Not only that, the vent carries this moist air from the dryer to the home's exterior. On the back of every dryer is a 4-inch diameter metal vent that expels the water-laden air.

Why Dryer Vents Are Necessary

With most dryers, you cannot blow this air into your house interior. The air is moved from the dryer to the exterior with a flexible, semi-rigid, or rigid tube. One end of this tube attaches to the dryer, and the other end attaches to a hole cut in the side of the house. Blowing moisture-laden dryer air directly into the home promotes mold and mildew. So, dryer vents are critical and must be vented to the exterior.

There is an exception, though. Ventless dryers are an increasingly popular option. Ventless dryers condense the moisture-laden air back into liquid water again, collecting it in a bin or sending it into the home's drainage system. Ventless dryers take longer than vented dryers: up to twice as long. But users report that the dried clothes feel softer.

Best Type of Dryer Venting Tube

The dryer duct, or tube, is at the heart of dryer venting. Major types of dryer ducts include:

Aluminum Foil Duct: Inexpensive and easy to find, foil accordion-style ducts are the most common type of dryer duct. Coiled metal wire gives these ducts their cylindrical shape. Since these ducts are metal, they are inflammable. Classified as a transition duct, this product cannot be used within wall assemblies.

Best for: Aluminum foil dryer ducts are best for saving money since these are the most common type around. Prices are usually competitive and large home centers may have several options to choose from.

Semi-Rigid Metal Duct: This type of dryer duct looks similar to an aluminum foil duct in that it is an accordion-style flexible metal tube. It also is a transition duct that must be used outside of wall assemblies. The difference is that the metal is semi-rigid and less prone to crushing.

Best for: Since the inside of the duct is smooth, lint and other debris move more freely through the duct. If your dryer has chronic problems with lint clogging the aluminum foil duct, you may want to consider moving to a semi-rigid metal duct.

Rigid Metal Duct: The only dryer vent that can be installed within a wall, the rigid metal duct has a smooth interior to encourage the flow of air and lint.

Best for: When you want to tuck the dryer venting tube away and see as little of it as possible, install a rigid metal duct.

Slim Duct or Periscope: Constructed of rigid metal, a slim or periscope dryer vent allows you to push the dryer back close to the wall. As a transition duct, it must be kept out of the wall assembly.

Best for: To make the dryer venting nearly invisible, choose a rigid metal duct. But if you're not ready to break into the wall, the second best option is to install slim or periscope ducting.

Vinyl Vent: Once widely used, the plastic or vinyl dryer duct is no longer recommended as it is a fire hazard. Some codes do not allow these vents.

Best for: None. Vinyl venting tubes, even if available, have been surpassed by better venting tubes and may even be illegal in your area.

How to Install a Dryer Vent and Tube

Installing a vent and tube to a dryer is a simple project, especially since it is possible to buy complete dryer vent kits with all of the items you need.

The most difficult part is cutting a hole in the side of the house. This can be accomplished with a jigsaw, multi-tool, or reciprocating saw.

1. If the rigid aluminum vent pipe has been shipped flat or in any other non-cylindrical shape, form the pipe into a cylinder while wearing gloves.
2. Cut a 4 1/4-inch diameter hole in the exterior wall.
3. Attach the plastic vent cap to the vent pipe.
4. From the outside, insert the vent cap and pipe assembly through the hole, then screw it into place.
5. In most setups, a four-inch diameter flexible metal tube attaches to the dryer's rear vent with spring or plastic clips.
6. Attach the other end of the metal tube to the vent cap and pipe assembly that is attached to the house.

Cleaning the Dryer Vent

Dryer vents filled with lint and other debris are responsible for close to 3,000 home fires and five deaths per year. Cleaning dryer vents regularly keeps you and your family safe and your home out of danger.

After unplugging the dryer from the electrical receptacle, detach the tube that runs from the dryer to the house. With a vacuum, clear out the tube. If you cannot reach all areas, purchase a new tube. With the vacuum, clean the vent leading out of the dryer and the vent cap assembly attached to the house. Clean out the dryer's lint filter. Replace all items.

Dryer Vent Care and Troubleshooting

Keeping the dryer vent duct clean and airtight will only assist in the overall operation of your dryer. Common problems that frequently arise:

Tube Detaches From Dryer

Dryer duct tubes often fall off of the dryer or the wall attachment points. You'll know the source of the problem as soon as you walk into the laundry room: the air will be hot, moist, and will smell like laundry detergent.

Remove the tube and clean it out; sometimes, the weight of lint combined with air pressure causes the tubes to disconnect. Reattach with new spring or plastic clips.

Punctured Dryer Vent Tube

The foil on aluminum foil ducts is very thin and is subject to puncturing. For small repairs, purchase aluminum foil tape to patch the hole. Do not use any other tape for this repair.

If the tube has several punctures or if the hole is large, purchase an entirely new duct tube. Duct tubes are inexpensive, usually $10 to $20.

Dirty or Clogged Vent Tube

Lint and other debris in dryer duct tubes is hazardous. Most likely, your dryer is missing its lint filter. Or if you have a filter, the filter fabric might be imperceptibly torn away. Purchase the correct lint filter. Do not repair.

Vermin in Dryer Tube

Mice, rats, and other vermin can enter your home from the outside via dryer duct tubes. On the exterior of your home, examine the plastic or metal grille covering the louvered vent exit. The grille should be firmly attached. Reattach or buy a new grille and attach that one.

Cold Air Coming in Through Dryer Vent

Whether it's a bathroom exhaust fan, kitchen hood vent, or dryer vent, any type of penetration into the house envelope for venting can let in cold air. With dryer vents, first go outside and check the louvered flaps at the end of the vent line.

Except when the dryer is running, the flaps should always be in a down and closed position. But dryer lint can get stuck in the flaps and keep them open. Remove the lint by hand or with a shop vacuum, then close the flaps.