An electric dryer DOES need to be vented-out of doors.
Gas dryers should never be vented indoors due to fire and carbon monoxide poisoning hazards, but many wonder if this includes electric dryer venting. Choosing not to vent an electric clothes dryer to the outside of the home could cause two problems that could become hazardous-an accumulation of lint, and excessive humidity. The practice may also be illegal in your state.
Clothes Dryer Venting Indoors Causes Excess Humidity
A dryer full of wet clothes can contain up to one-and-a-half gallons of water. If not vented to the outside of the house, this water evaporates into the surrounding environment causing a condensation build up and subsequent water damage. Not only will walls and flooring materials sustain considerable water damage, the condensation build up could ultimately lead to the growth of health hazardous mold and mildew.
What about Indoor Dryer Venting Kits?
The suggestion to vent an electric clothes dryer indoors to gain heat abounds across the internet. In fact, there are commercial kits that make this possible. These units require vigilante scrutiny and even under the most careful conditions have the potential to create a variety of problems.
The indoor dryer unit is a simple design that includes a short length of dryer transition duct and a lint trap. You attach one end of the dryer transition duct to the dryer while the other is attached to the lint trap. The lint trap is then filled with water, which will collect the accumulation of lint. Just like venting the dryer directly into the room, the water in the lint trap will evaporate and cause condensation build up within the room. Also, because the ducting material is not in a fixed position, it can bend, crack, or break becoming a potential fire hazard.
Dryer Venting and Building Codes
If you still want to risk venting your clothes dryer indoors, make sure that this practice is not illegal in your state. Some state building codes require that dryer exhaust systems be vented outdoors. For example, Massachusetts State Building Code 780 CMR 6501.1 states, "dryer exhaust systems shall be independent of all other systems, shall convey the moisture to the outdoors, and shall terminate on the outside of the building". The only exception to this building code is in the case of the installation of listed and labeled condensing clothes dryers.