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What Is a Heat Pump Ventless Dryer

The first thing you need to know about heat pump dryers is that they are a type of ventless dryers, meaning that they do not have an exhaust vent. Heat pump dryers have a similar composition to condenser ventless dryers. However, there are a couple of differences in their mode of operation, the key difference being their method of heat generation.

Here is a detailed guide on the workings of heat pump dryers. In this article, I shed light on the mechanism of heat pump dryers. I also provide information on how they’re different from other dryer models, and the cost of setting up as well as running the unit. I also highlight the pros and cons of heat pump dryers. 


A heat pump ventless dryer uses heat pump technology to heat the air instead of a heating element. Coolant runs through coils and is compressed and expanded to provide and remove heat, respectively. Air is pushed over hot coils before entering the drum and over the cool coils after leaving the drum.

Defining a Heat Pump Ventless Dryer

The name “heat pump ventless dryer” covers all the main and defining features of this type of dryer but many people do not actually know what all these terms mean. I didn’t myself until I had done some research. Even then, I had to put in a few more hours to fully understand the “heat pump” part!

A heat pump ventless dryer is a dryer that has an in-built condensing and filtering system that negates the need for the appliance to be vented outdoors. The term “heat pump” refers to the technology that this dryer employs to dry your clothing.

The mechanism of this technology is what makes these dryers stand out as the most efficient models available today.

How Heat Pump Dryers Work

Heat pump dryers function through a closed-circuit system where the air is re-used to dry clothes. Here is a summary of how they work. 

  • Air is drawn into the dryer.
  • The dryer heats up the air.
  • It uses heated air to dry the clothes.
  • The heated air leaves the drum and is cooled.
  • Moisture is extracted during the cooling process.
  • The air is reheated and recycled into the drum.

Now let’s get into the process in a bit more detail.

Refrigerant Heats Air 

One of the unique features of heat pump dryers is the presence of refrigerant, which is responsible for heating and cooling the air before and after it exits the drum.

The coolant is contained in coils over which the air flows; the coolant and air do not come into direct contact. Within the coils, the coolant transitions from gaseous to a liquid state during the course of the drying cycle.

Cooling coil

In its liquid state, the coolant cools the air, and while in its gaseous state, the coolant heats the air before it re-enters the drum.

Like other dryer models, heat pump dryers draw in air from the room. Once the air enters the dryer it is pushed over the coils in the compressor side of the heat pump.

In the compressor, the coils are smaller, so the coolant flowing through them is pressurized. As the volume decreases, the pressure increases and so does the temperature. This heat is then transferred to the air blowing over the coils.

Hot Air Enters Drum And Removes moisture from clothes

The heated air proceeds to the drum and while the dryer rotates, it absorbs moisture from your clothes through evaporation. After every cycle, moist air exits the drum.

Evaporator Cools Air and Extracts Moisture

After the hot damp air exits the drum, it passes through the primary and secondary lint filter on its way to the evaporator. The refrigerant coils in the evaporator are much wider and the coolant runs through them in a liquid state.

The greater volume means there is less pressure and less pressure means lower temperatures. The heat is transferred from the air to the coolant (down the temperature gradient).

As the air loses heat, it also loses its ability to hold water. As a result, the moisture in the air condenses out and is collected in a water tank located in the dryer or drained out through a hose.

Water tank in white ventless dryer

Air is Reheated and Re-cycled

The cool, moisture-free air is then reheated following the steps discussed in the first part of this section. After it is re-heated the air is sent back into the drum. 

The process is repeated until the clothes in the drum are dry. 

The fact that the air is recycled is another desirable feature of the heat pump ventless dryer.

How This Differs from Other Dryers

The fact that the heat pump dryer uses heat pump technology (coolant in coils) to heat the air makes it different from every other tumble dryer.

Vented dryers utilize an electric heating element or a gas burner to generate heat, and condenser ventless dryers use an electric heating element to generate heat.

Both heat pump and condenser dryers function without a vent. So, they recycle air to dry fabrics. However, due to the lack of a heating element, the operating temperature of heat pump dryers is considerably lower than that used by vented and condenser dryers. 

difference of gas dryer, condenser dryer and heat pump dryer

Average Load Capacity

Heat pump dryers come in different models and sizes. So, the exact load capacity of your heat pump dryer would depend on the drum size.

The size of the dryer usually influences the size of the drum. Although it’s possible to find heat pump dryers with sizes similar to that of a standard dryer, the size of most heat pump dryers is usually relatively small in comparison to conventional, vented models. 

Vented dryers can take up an average of 4 kg to 9 kg of wet fabrics while heat pump dryers have an average load capacity of 3 kg to 5 kg.  

Typical Drying Time

The operating temperature of heat pump dryers is lower than what is used by both vented and condenser dryers. As a result of their lower operating temperature, heat pump dryers take longer to dry clothes

The lower operating temperature of heat pump dryers is mostly due to the lack of a heating element as well as the absence of an external exhaust system. 

Here’s a table showing the time the different dryer models would take to dry an identical load of laundry. 

Dryer TypeDrying Time
Heat pump dryer1 hour 20 minutes to 1 hour 40 minutes
Condenser dryer1 hour to 1 hour 15 minutes
Vented dryer30 minutes to 45 minutes

Heat Pump Dryers: Expenses

Purchasing Cost

Heat pump dryers are the most expensive dryer models on the market right now. The average cost of purchasing a heat pump dryer is between $800 to $1300. Depending on the model and dryer features, they can cost more, with some models being priced up to $3000. 

Running Cost

The dryer operates at temperatures lower than that used by both vented and condenser dryers. As a result, they do not cost as much to run. On average, a heat pump dryer uses 2.16 KWh, which, depending on the cost of electricity, could cost between $0.24-$0.30 per drying hour.

This is a lot less than condenser dryers and vented dryers which use between 5.2 kWh and 5.34 KWh. Condenser dryers cost about $0.58-$0.6 per drying hour and vented units cost between $0.59-$0.70 per drying hour.    

But the actual amount you spend would be determined by the cost of electricity in your area. 

Installation Cost

Installing a heat pump dryer is pretty inexpensive. 

The only thing that you might have to spend on while setting up the unit is an electrical outlet, ideally one that’s 240V. An electrician would charge between $120 to $200 to install the outlet. But if you’re skilled enough to do it yourself (and doing so is legal in your area), you’ll be looking at spending between $15-$30. 

Guaranteed for Life, NEMA 14-50 Commercial / Industrial Grade U.L. Approved 50 AMP 240V Receptacle

Heat Pump Dryer: Pros and Cons

ProsCons 
More energy-efficient than other dryer modelsCosts more than vented and condenser dryers
No need to install a ventTakes longer to dry clothes
Can be installed anywhereWater container must be emptied manually
Long-lasting
Gentler on fabrics than other dryer models

Sources

https://www.appliancesonline.com.au/academy/appliance-news/heat-pump-dryers-are-they-worth-the-money/

https://www.energystar.gov/products/heat_pump_dryer

https://www.youtube-nocookie.com/embed/zw183KZQNwc?width=640&height=480&iframe=true

https://www.iernaair.com/blog/heat-pump-service/the-refrigerant-in-your-heat-pump-what-you-need-to-know/

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