How Washer Dryer Combos Work

There are two types of all-in-one washer-dryer combos -- vented and ventless. "We have a vented version that we sell mostly to our marine and RV markets, but our ventless version is the one that is most common for use in high-rise apartments and condos, that type of thing," says Lee.

A vented unit basically works like a regular front-loading washer and a regular dryer. The wash cycle includes tumbling the clothes with water and soap until they're clean, then spinning them to help remove some of the excess water [source: LG Electronics]. For this drying system, the unit takes in air from the surrounding room and heats it up [American Gas Association]. This heated air is then spun with the clothes. The air picks up moisture, producing steam, which leaves the house via the vent. The system then takes in new air from the surrounding room and heats it up again to restart the process.

Alternatively, a ventless unit is a unit that doesn't require an outside exhaust. "There really isn't any washing difference; the main difference is on the dry side," says Lee. "The machines use a condensing drying system, and it works like a dehumidifier."

In a ventless system, wet clothes start in the drum. A condensing chamber, which can be plastic or metal, is cooled. Then the air inside the dryer drum is heated. As the drum spins, the interior heated air takes up moisture from the wet clothes. This moisture-laden air is then circulated through the cooled condensing chamber, which produces condensation, or a change of the moisture in the air into its liquid form of water [source: Lee]. The condensation then leaves the unit by the water drainage tube. The dry, hot air is then recirculated with the clothes, and the process repeats itself [source: Creative Laundry Systems, Inc.].

Whether you choose a vented or ventless unit, all-in-one combination units offer a range of program options to best fit your fabric care needs. You can wash and dry your clothes in one process, or you can also set the units for a "dry only" or "wash only" cycle [source: Equator Advanced Appliances]. Units also offer a range of settings, including delicates, timed drying and extra rinse [source: Creative Laundry Systems, Inc., Equator Advanced Appliances, Summit Appliance].

So how efficient are washer dryer combos?

When choosing between a separate washer and dryer or an all-in-one combination, there are some advantages and drawbacks that should be considered. One of the most obvious advantages of an all-in-one unit is the space savings. Since many of these units are about the size of a standard dishwasher and can fit under a countertop, they offer those with limited space a laundry option [source: Lee]. Since you don't have to run a vent outside, the ventless versions offer even more flexibility of positioning.

Along with space savings, there is also an element of time savings. Since these units have settings to let you both wash and dry at the same time, you don't have to worry about remembering to switch over the laundry. This may also alleviate the need for a second wash if you forget to switch over those wet clothes and they start to smell moldy.

Finally, all-in-one units can be energy savers. First off, the washing portions of these machines work much like front-loading washing machines. Front-loading washing machines typically use less water than traditional top-loading units; for this reason, these units also use less energy to heat the reduced amount of water [source: Federal Trade Commission, California Energy Commission]. Front-loaders also can spin more quickly and usually produce drier clothes at the end of the cycle, meaning less time in the dryer [source: Federal Trade Commission, California Energy Commission].

All-in-one units do have their drawbacks, or at least qualities that you should consider before purchasing one. While washer dryer combos are space-saving, that can mean a reduced capacity when it comes to load size [source: Lee]. Maximum load sizes for a combined wash-and-dry cycle can range from 6-10 pounds depending on the unit [source: LG Electronics, Ariston]. A cycle for an all-in-one unit can also take a longer time than stand-alone machines, ranging from about 2-3 hours [source: Lee, LG Electronics].

With both advantages and disadvantages, a washer dryer combo must be evaluated as any other appliance before making your final decision on the laundry system that's right for your needs. For lots more information on home appliances, see the links on the next page.