An indoor dryer vent is one that doesn't have to be routed outdoors. Although a dryer is best vented outdoors for safe operation and heating efficiency, using an indoor vent can be more practical if the laundry room is located too far from an exterior wall, or cutting through the exterior walls is too difficult. An indoor dryer vent kit typically includes a reservoir of water to catch lint and other debris from the dryer that would otherwise be dissipated into the air by an outdoor vent.
A typical outdoor dryer vent kit includes rigid stainless steel duct pipes, clamps, and an exterior vent cap. The duct pipes are installed along the shortest path from the dryer to an exterior wall and clamped to the dryer vent opening. The vent cap is usually screwed to the siding. Installation requires cutting a 4-inch (10 cm) hole in the side of the house through which the duct pipe attached to the vent can extend. It may be impractical to make this hole if the house is brick or has another type of siding that is difficult to cut through.
Using an indoor dryer vent circumvents problems associated with routing pipes and cutting through brick walls. Instead of a vent cap, the pipes of an indoor dryer vent kit terminate in a reservoir of water that can be installed in any convenient location, even directly adjacent to the dryer. Some reservoirs can be mounted on the wall with screws, and some are designed to simply sit on the floor in an accessible location. Instead of rigid pipe, an indoor dryer vent kit usually includes a length of flexible duct pipe that can be secured to the dryer outlet and the reservoir with clamps.
Properly venting a dryer is essential for its safe operation and for the comfort of the home. Dryers expel warm, moist air that can significantly increase the humidity of the laundry and surrounding rooms and cause a host of problems, including damage to the drywall and the increased occurrence of mold. A dryer also expels lint, which can create a fire hazard if not collected and disposed of properly. The water in the reservoir of an indoor dryer vent kit collects both excess moisture and lint effectively, but must be cleaned at regular intervals. To facilitate cleaning, the reservoir usually has screw threads or snaps to make it easy to disassemble without the need for special tools.