How does a heat pump tumble dryer work?
Heat pump is the latest technology in tumble dryers, but how does it actually work? It sounds complex, but it’s relatively straightforward and good to know if you’re considering upgrading. After all, these are the most energy efficient type of tumble dryer; one reason why they dominate our list of the best tumble dryers.
To help answer your questions, we’ve explored exactly how this technology differs from other types of dryer, including its pros and cons. Plus, we’ve looked into exactly how much you could save by converting.
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Vented vs condenser vs heat pump tumble dryers
There are three main types of tumble dryer to choose from, each of which dries your clothes in a different way:
Vented tumble dryers
Not as predominant in the UK, but there are still some models available. These draw in air from the room, which is heated via a heating element (on electric models) and applied to the load. This is then vented along with any residual moisture through a hose to the outside (so you’ll need to be near a window or duct). These generally come at the cheapest price point of the three. Gas models do exist, as well as electric, for different methods of heating the load, but electric is the more popular of the two in the UK.
Traditional condenser tumble dryers
These use a heating element to heat the air that’s used to dry the clothes, then the air passes through a condensing chamber where it’s condensed into water, which is collected in a water tank to be emptied once full, or drained separately via a drain hose if your machine allows. There’s more freedom of placement for these dryers, as they don’t need an external vent, although the room should be well ventilated with access to cool air. Condenser dryers are more expensive than vented versions, but not as expensive as heat pump dryers. However, they do use more energy compared with heat pump dryers, as they operate at higher temperatures and don’t reuse the hot air.
Heat pump tumble dryers
Heat pump dryers are a type of condenser dryer, technically speaking, but they differ from the traditional models because they use a closed loop system. This removes moisture from clothes via hot air, which then passes through an evaporator to extract the water as condensation. This collects in a separate tank to be emptied (or drained away via a drain hose if attached), then the same air is reheated and recycled into the drum, rather than being vented. The dryers are generally the most expensive of the three options, but they’re also the most energy efficient, so you would make back the additional cost over time. Like traditional condenser models, you’re not limited in placement by a vent or hose.
Why are heat pump tumble dryers so energy efficient?
Heat pump tumble dryers operate at a lower temperature compared with vented and traditional condenser models, so they will take longer to dry the load, although this does make them gentler on your clothes. These dryers ultimately use less energy, as the hot air is recycled rather than needing fresh power to heat it up.
According to Gwilym Snook, tumble dryer expert at ao.com: ‘The clever part, and what
sets a heat pump apart from other tumble dryers, is that it uses the extracted heat energy to further heat the air entering the drum – rather than venting it out.’ That means the residual heat isn’t wasted, and reheating fresh air via a heating element isn’t needed.
Having said that, the energy consumption does differ from one heat pump tumble dryer to another. That’s why we recommend opting for one with a moisture sensor, so it will stop the cycle automatically once the clothes are dry. It’s also worth checking the energy rating, so you can see how models compare.
How much can heat pump tumble dryers save?
According to The Renewable Energy Hub, the most efficient heat pump tumble dryer will cost as little as £25 per year to run, compared with conventional models costing upwards of £77 per year. That’s over three times the energy consumption.
Pros of heat pump tumble dryers
More energy efficient – recycles hot air rather than venting it.
Better for the environment – less energy use means a smaller carbon footprint.
Gentler on your clothes – less heat means it’s less abrasive on your laundry.
Easy to place around the home compared with vented – no need to be near a window.
Cons of heat pump tumble dryers
Takes longer to dry – because it operates at a lower temperature.
More expensive up front – although you'll make this back in energy savings.
Not ideal in a garage or basement – the surrounding environment should be at room temperature for the best performance.
Overall, a heat pump tumble dryer will cost more up front, but will save you money on your energy bills over time. So, if your budget can stretch to it, it’s worth the expense. If cost is a concern, you could always check out the best value heat pump tumble dryer from our tests (Hisense DH5S102BW 5S Series).
ASKO T608HX.S Freestanding Anticrease Heat Pump Dryer
Score: 94/100
With 18 programs, a clear LCD display, a well-lit drum and easy-to-empty water tank, this heat pump dryer aced our tests, delivering dry, crease-free laundry. Note it has the smallest capacity of the models we tested, at 8kg.
Miele TEL785WP Freestanding Heat Pump Tumble Dryer, 9kg load
Score: 93/100
As well as drying your clothes, this Miele model will also inject fragrance, so they come out not only dry and crease-free, but scented, too. Testers loved how quiet it was, found the drum well-lit and said emptying the water tank was effortless. A very reliable all-rounder.
Hisense DH5S102BW 60cm Freestanding 10KG Tumble Dryer
Score: 92/100
This dryer boasts lots of great features, including a clear digital display, bright drum light, start-delay feature, and child-lock. It also comes with a drying rack. It performs well too – combining efficient energy consumption with effective drying. The water tank isn't the quickest to empty but that's the only niggle.
Boss It Rapid Dryer Ball for Tumble Dryer
Score: 79/100
This dryer ball's mirrored surface helps reflect heat onto your laundry, speeding up drying times. In our lab tests, it cut down our machine's drying times by 30 minutes and reduced energy consumption. Our panel also found that drying times were shortened and cycles more efficient when using the ball, and everyone found it simple to use, albeit a little more noisy.
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