Condenser (Ventless) Dryers In USA
Maytag, Hotpoint and Frigidaire all had "ventless" condenser dryers back in the 1950's. The first two were water cooled and the last used the same air/condenser coil system found in European (non-heat pump) condenser dryers today. The Frigidaire only extracted 50% (give or take) of he moisture according to CR, the rest was sent into the room.
By the 1970's or sooner no American appliance manufacturer offered condenser dryers of any sort. But in the 1980's or early 1990's you started to see imports of European versions by Asko, Miele, Creda, Malber, Equator and maybe a few others. Malber and Equator used water cooling systems, and the rest closed condenser coil systems.
As to why condenser (non-heat pump units) take longer and consume slightly more energy than vented dryers is a simple matter of physics and design.
With a vented dryer a constant flow of heated and dry air replaces the moisture laden air that is sent out of the dryer. This results in slightly faster drying times. OTOH condenser dryers are like air conditioners or refrigerators with only "half" a cooling system. That is they rely purely upon the difference between ambient room temperature air and what is inside the dryer to remove moisture. Because the air circulating is often somewhat still moisture laden it cannot pick up as much when it returns to the clothes. Much depends upon the climate/air temperature and humidity levels of the place where the condenser dryer is located.
It comes as no surprise that condenser dryers are popular in Northern European countries where outside venting isn't possible. During the colder months those countries provide the ideal climate (cool to cold) so the dryer can take in such air and thus "condense" more moisture out of a load of laundry.
OTOH during a hot humid NYC summer, or really any place where it is warm to hot and humid a condenser dryer will take ages to finish a load if it can complete it at all. You can get good results by turning on the air conditioner (provides that aforementioned cool and dry air), but then you are not only using energy to dry laundry but to cool the house and make the dryer work.
Can only use my AEG condenser dryer from about November to March or early April. Once outdoor temps begin to climb into the high 50's or above it just isn't worth the bother. As it is my "compact" Whirlpool portable will dry a full load faster than the condenser dryer.
Being as all this may again condenser dryers weren't about energy efficiency from a start. More how to solve a problem of using a tumble dryer where venting wasn't possible.
Case in point many new apartment developments in NYC are featuring laundry facilities with condenser dryers. This is mainly because the laundries are being located where access to an outside wall (for venting) isn't possible. When you are converting a former Verizon, Woolworth, MET Life, building and or dealing with other issues involving creating apartments in the City you have to think outside of the box.
All this being said condenser dryers do leave things with a wonderful scent. They also leave terry towels and other items more fluffy and soft than vented dryers IMHO. That however in no way endears them to me that much more.
