Heat pump clothes dryers use heat pump technology to extract moisture from your clothes. Rather than generating heat with a gas burner or electric coils, a heat pump moves thermal energy from one area to another using a refrigerant and a condenser—like an air conditioner in reverse. As with other heat pump technologies, such as air source heat pumps, these dryers are energy efficient.

While a conventional electric or gas dryer draws in cool air from your home and expels warm, moist air through a vent, a heat pump dryer circulates warm air within a self-contained system, eliminating the need for an exhaust vent. The ventless design and compact size of a heat pump clothes dryer allows for plenty of flexibility in its placement in your home. Compared to a conventional electric dryer, energy savings can be up to 60%.

Diagram of how a heat pump dryer works.

Heat pump clothes dryers deliver both ventless convenience and energy efficiency. The dryer warms, cools, and condenses the same air within a self-contained system. Like an air-source heat pump, a heat pump dryer contains a closed loop of refrigerant lines and two sets of coils—an evaporator (cold) and a condenser (hot). Condenser coils heat the air (1) sending hot, dry air through the drum (2). Warm, moist air exits the drum. (3) It passes over the evaporator coils to cool the air and extract the moisture (4). The moisture drains away or collects in a removable tray for you to dump out later (5). The cycle begins again by the condenser coils heating the air (1) sending hot, dry air through the drum, repeating the process.

TYPE OF DRYERHOW IT WORKSVENT TO OUTDOORS?
Heat pump clothes dryerExtracts moisture from clothes within a closed-loop system using heat pump technology—the most energy-efficient optionNo
Hybrid heat pump clothes dryerUses a mix of heat pump technology and electric coils, which speeds up drying time but is not as efficientNo
Combined condensing washer/dryerWashes and dries in a single cycle in a single applianceNo
Conventional electric dryerGenerates heat using electric resistance and expels hot air through an exhaust ventYes
Conventional gas dryerBurns fossil fuels to heat the air inside the dryer and expels hot air through an exhaust ventYes

Electricity requirements

If you previously had a gas dryer, installing a heat pump clothes dryer may require upgrading your electric outlet to 240-volt. If all-new wiring isn’t an option, some manufacturers offer 120-volt models. Most existing conventional electric dryers already require a 240-volt outlet.

Size

In general, clothes dryers come in two size ranges. Full-size (or standard) dryers typically have a capacity of 6 or more cubic feet, while compact dryers are typically around 4 cubic feet. Many heat pump clothes dryers are compact, but full-size and full-size hybrid models are also available. While compact models are smaller, a field study found that 95% of loads that people dried in their full-size dryer would also fit in a compact dryer.

Using your heat pump clothes dryer

Overall drying time depends on the moisture content in the clothes coming out of the washer. The average load will take longer to dry in a heat pump clothes dryer than in a conventional dryer. Because heat pump dryers extract moisture from the clothes at a lower temperature, they also tend to be gentler on your clothes, easing wear and tear. Heat pump dryers don’t vent air to the outdoors, which means all the heat from the dryer remains in your home. This has the added effect of making the room slightly warmer than a conventional, vented dryer would—especially if the dryer is in a small, enclosed space. Keep this in mind when deciding where to place the dryer in your home.

Maintenance

A heat pump clothes dryer is easy to maintain. In addition to the normal lint trap, the dryer contains an additional lint filter to protect the intricate coils from the lint contained in the recirculated air. This will need to be cleared every few cycles and is easy to access and clean.

Moisture from the dryer is collected in a removable tray, which you’ll need to empty out every cycle. You can skip this step by affixing a hose to the dryer so the water drains into a nearby sink or floor drain.

The condenser coils may have to be cleaned every month or so. You can do this simply with a brushed vacuum head. As with any appliance, regular maintenance will keep your heat pump dryer working most efficiently and will help maximize its useful life.

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