Clothes dryer heat recovery systems are designed to save money and the environment by taking advantage of the warm air created by your clothes dryer instead of just letting it escape into the world outside your home. They range from very simple indoor venting systems to more complex heat exchange systems.
The simplest method of dryer heat recovery is just to vent the warm air your electric dryer creates into your home during cold months to save on your home heating bill instead of directing it outside. (This is an absolute no-no for gas dryers) Several manufacturers make specialized water filtration systems to take as much lint out of the exhaust as possible before the dryer releases it into your home.
Though this is the simplest method, there are several problems that this method creates. Venting a clothes dryer indoors may also be against building codes in your area. You can read more about it here: Does an Electric Clothes Dryer Need to Be Vented Outdoors?
Heat Exchange Systems
When a dryer exhausts warm air through its venting system, it must bring in new air to replace the escaping air. The dryer has to use energy to heat this new air to use it to dry the clothes. Heat exchange systems use the exhaust’s hot air that’s escaping from the dryer to heat the incoming air. This way the dryer has to expend less energy heating enough air to completely dry every load of laundry. You can save money on your utility bill and save the environment by consuming less energy.
Problems Associated with Heat Recovery Systems
Clothes dryer heat recovery systems aren’t viable with gas-powered dryers because the exhaust fumes include carbon monoxide, a colorless odorless gas that can lead to death by suffocation. More than 2000 people die from carbon monoxide poisoning every year in the US. Also, about five pints of water are removed from every load of clothes you dry. This moisture escapes through the ventilation system. If you route the ventilated dryer exhaust back into your house, you are pumping this moisture in with it. If you reside in an arid climate or have a badly insulated house, this probably won’t create a problem. But if you live in a climate that is damp or have a well-insulated house that isn’t equipped with a mechanical ventilation system, this moisture will be trapped in your house and can cause mold to grow. If condensation already appears on your windows during cold weather, your house is probably too well insulated and not well vented enough to pipe moist warm dryer exhaust in without consequences.
“Pennsylvania Inventor Develops Clothes Dryer Heat Recovery System.” US Fed News Service, Including US State News. HT Media Ltd. 2007. HighBeam Research. 1 Apr. 2010 <http://www.highbeam.com/>.
“Dryer Heat Recovery System.” Progress Energy. N.p., n.d. Web. 1 Apr. 2010. <progress-energy.com/custservice/flabusiness/efficiency/CA/library/MISC002.asp>.
Hellevang, Ph.D, Kenneth. “Keep Your Home Healthy.” NDSU. N.p., n.d. Web. 1 Apr. 2010. www.ag.ndsu.edu/pubs/ageng/structu/ae1204w.htm.
Maxwell, Steve. “Reclaiming Dryer Heat.” Home Envy. N.p., n.d. Web. 1 Apr. 2010. www.homeenvy.com/db/5/405.html.