A clothes dryer, also known as tumble dryer or simply dryer, is a powered household appliance that is used to remove moisture from a load of clothing, bedding and other textiles, usually shortly after they are washed in a washing machine. Many dryers consist of a rotating drum called a "tumbler" through which heated air is circulated to evaporate the moisture, while the tumbler is rotated to maintain air space between the articles. Using these machines may cause clothes to shrink or become less soft (due to loss of short soft fibers). A simpler non-rotating machine called a "drying cabinet" may be used for delicate fabrics and other items not suitable for a tumble dryer. Drying at a minimum of heat for thirty minutes kills many parasites including house dust mites, bedbugs, and scabies mites and their eggs; a bit more than ten minutes kills ticks. Simply washing drowns dust mites and exposure to direct sunlight for three hours kills their eggs. Combination washer-dryers perform both functions in one device. Others include steam to de-shrink clothes and avoid ironing. Tumble dryers Tumble dryers continuously draw in the ambient air around them and heat it before passing it through the tumbler. The resulting hot, humid air is usually vented outside to make room for more air to continue the drying process. It is simple and reliable, and therefore has been widely used. Improvised methods of salvaging this heat for in-home heating, by use of inline vent boxes equipped with Air Damper to redirect moist heated air to indoor areas, will also increase humidity within a dwelling. Although this may be beneficial in dry winter conditions, excess humidity from these devices increases likelihood of mold, mildew, and bacterial growth inside a home. Indoor venting may also be against local regulations. Gas dryers, unlike electric dryers, must always be vented outdoors, as the products of combustion are mixed with the moist air. Building codes and manufacturers' instructions usually recommended that dryers vent outdoors. An indoor lint trap kit poses a similar concern of increased humidity within the dwelling. "Long run" dryers might have an additional external exhaust fan to boost the exiting moist air through longer sections of vent pipe, as in apartments or dwellings where the vent cannot make a short direct connection from the dryer to the outside. Beyond issues with venting exhaust, other improvised efficiency efforts with conventional dryers attempt