Heat pumps are starting to catch a lot more attention for heating and cooling your home now than they have in the past. The same is true for other uses, but … this one really surprised me … what about putting a heat pump in your dryer? There’s some insanely cool, or should I say hot, engineering inside this dryer that doesn’t require a vent to the outside or a high voltage outlet. This thing runs off of a standard 15 amp household outlet and will use four to five times less electricity than a typical electric dryer. So if they’re that good, why aren’t they used everywhere? Well, I’ve been living with this Miele model for a while now and I have some thoughts on that. It’s one of my favorite pieces of new tech in my home. It’s kind of genius, but not perfect. How does this thing work … and are heat pump dryers even worth it?
I’m sure some of you probably think I’m a bit of a heat pump fanboy, but the technology really is incredible. It’s the most efficient way to generate heat … well, not really to generate it, but to move it, which is why it’s so energy efficient. I won’t go into all the details on how heat pumps work, but at a high level they capture heat from the environment and use a compressor to amplify that heat and put it where you want it. A big knock against heat pumps for heating and cooling your home is that they may be slow to respond, meaning it may take longer to heat or cool than other systems. Another is that they might not be able to get as hot as you need in super cold environments. While there’s a seed of truth to both of those complaints, it’s not that simple, and I’ve addressed this in other videos.
When it comes to a heat pump dryer like the Miele TXI 680 WP (a name that roles right off the tongue), you might hear similar concerns. For full transparency, I have no association with Miele and paid for this with my own money. Common complaints you might hear are that It doesn’t get as hot as a typical dryer, or that the clothes aren’t completely dry at the end of a cycle. On both of those, it’s somewhat true, but in practice I don’t think it matters. I’ll get to why in a minute.
First, the way heat pump dryers work is kind of ingenious. It’s essentially a closed loop system made up of two circuits. One of those circuits is the air circuit that helps to dry the clothes. The second circuit is the coolant circuit that extracts the heat and moisture from the processed air.1
As I mentioned before, a heat pump uses a compressor to generate heat. When you compress something, like a fluid that’s running through a heat pump system, that fluid is heated up. If you run that heated fluid through a radiator with cooler air passing through it, you’ll transfer that heat to the air. That’s the first step of this heat pump dryer.
This shouldn’t surprise anyone, but that hot air helps to evaporate and remove the moisture from the clothes you’re trying to dry. In a typical dryer, this hot moist air is what’s vented to the outside of the house. You need to keep pumping in hot dry air to fully dry the clothes. This creates a bit of a problem though, because as you’re ejecting that hot, moist air from the house, it has to be made up from somewhere else. That’s made up by colder outside air seeping into the house to make up for that exhausted air. Otherwise, the dryer would be trying to pull a vacuum, and your house probably doesn’t seal well enough for that. Ultimately, the dryer is not only drying your clothes, but costing you more money by forcing your HVAC system to work in overdrive to recondition the house from that energy loss. It’s a one-two punch of … why are we doing it this way?
Well, a heat pump dryer like this Miele doesn’t eject that hot, moist air. Instead, it recirculates it through that second coolant circuit I mentioned earlier. As you heat the hot air flowing into the drum, you’re helping to cool down the fluid that was passing through the radiator. That cooled-down fluid is then used in another radiator to cool down the hot, moist air that’s exhausted from the drum. This is basically like an air conditioner at this stage. When you cool hot, moist air you end up getting condensation, which is then collected in a water reservoir. You can also opt to run the condensation hose to a sink or drain so you don’t have to empty the reservoir after every couple of loads. But from our experience, emptying it is really easy and not too annoying. You could also reuse that water for other uses if you wanted to, like watering plants. I have run the hose to the nearby drain though for our setup.
That cooled heat pump fluid flows back through the compressor, is reheated and sent back to the first radiator. Then that cooled and dried air flows through that first radiator and is heated back up. It’s such a clever system that’s constantly recapturing and reusing the heat. So clever that if you compare the Energy Star ratings of this Miele model and a popular electric dryer from Samsung, you’ll see that the Samsung is estimated to use 608 kWh of electricity per year.2 The Miele is estimated to use 133 kWh per year.3 Where I live electricity prices are roughly $0.30/kWh right now. That means the Miele will cost $142.50 less to run each year ($182.40 vs. $39.90) … in theory.
The theory of this tech is really clever and cool (or hot), but how does it hold up? What’s the user experience actually like? My wife and I have been living with this thing for the past couple of months and it’s taken some getting used to. It’s not all sunshine and rainbows, but don’t take that as a negative review. There’s two main things that could be viewed as negatives. One of them takes getting used to, but the other might be a barrier for some of you.
The first thing is that when you dry a full load on the normal cycle of the dryer, the clothes often don’t feel fully dry when you take them out. This was something that really set my wife and I off at first. We would run loads through two dryer cycles to get them to the feeling we’re used to from every other machine we’ve ever used. We also tried running every load through the max settings, which increases the drying time and temperature (and lowers the efficiency), but that didn’t make a substantial difference.
This may sound pretty damning, but this is when my wife had an epiphany about a month ago. After a single cycle at the normal setting, she took the clothes out of the dryer even though they still didn’t feel fully dry. She gave a few items a shake in the air and… like magic, they suddenly felt dry! That’s when we realized what was happening. The moisture level inside the drum is higher than what you’d normally experience with a vented dryer. Because of that the clothes need to just air out for a minute or two outside of the machine to release that last bit of moisture and humidity as the clothes cool off. Since that epiphany, we’ve recalibrated what we expect the clothes to feel like when finished. We now have to give a few items the “shake test” before we pass judgment and have noticed that one cycle on the normal setting is enough the vast majority of the time. If we’re doing a load of something like towels, we may have to run it on max or extended modes. Bottom line: this perceived negative is real, but it’s more about expectations and recalibrating yourself than anything else.
The second negative is one that can’t be recalibrated, but has nothing to do with the heat pump technology. This Miele is tiny. Like really tiny. The drum capacity of this unit is 4.02ft3 (0.11m3). I’m sure everyone in Europe is laughing at the fact that: 1) I’m using cubic feet, 2) I’m not air drying my clothes, and 3) that I think this is small. On point 1, I’m American. One point 2, Air drying isn’t always a great option, so I’m going to put that to the side (go ahead and argue about that in the comments). As for 3, the size, I’m American. This Miele is pretty typical for Europe from what I understand. Here in the US, though, we like everything big, and dryers are no different. Typically you’re going to see something 7-8ft3, so about twice the capacity.
If you’re a family of 4 or 5 people, this size of dryer is going to be challenging for you to say the least. For my wife and I, it’s just fine … but again, it took some getting used to. So, depending on how much laundry you’re running through as a family every week, the size of this specific dryer may be a dealbreaker.
That actually leads me to one of the questions I brought up in the beginning. If heat pump dryers are so ingenious, why aren’t we seeing them everywhere? I think part of the answer to that question is cultural. There hasn’t been a big desire for crazy efficient dryers here in the US until now. With electricity prices rising, that desire is shifting. And if you’re like me and trying to produce as much energy as you use over the course of a year with solar power, you’re keenly aware of obtaining energy efficient appliances to help with that goal. And if you want to avoid exhausting conditioned air outside your house, a ventless dryer is super appealing.
There are a bunch of heat pump dryers hitting the market right now from different manufacturers, and some of those are much larger than this Miele. LG has one that’s roughly the same size as mine, but they also have something they call the WashTower. It’s a stacked washer/dryer combo that has a 7.2ft3 dryer capacity. The heat pump technology works in pretty much the same way as my Miele. It does require a 240 volt outlet though.
GE also just came out with a single combo unit in their Profile line that is crazy cool … or hot. It has a 4.8ft3 capacity, but what sets this apart is that it washes and dries in the same drum. I know single drum combo units like this have existed for some time, but I’m not aware of any heat pump models like this one. Best part is that it also runs off of a standard 15 amp household outlet, just like the Miele. Because everything is in one drum, you could set this on a timer to run overnight and wake up in the morning with fresh, dry clothes. And if you live in an area with time of use rates for your electricity, you can probably save some money by running it overnight. I love that.
One last thing on the point of why a standard household outlet is so important. It opens up a lot of flexibility for where you put your washers and/or dryers. For my Miele dryer I can put it anywhere I want because it doesn’t require a vent and wouldn’t require an electrician to install a new outlet. If we found that one dryer wasn’t enough, we could easily put another unit somewhere like our bedroom closet, no extra wiring or ductwork required.
Finally, the ultimate question I’m sure that’s on everyone’s mind: what about the cost? Miele is kind of a premium brand, so it has a high price tag regardless of the underlying technology. This model cost $1,799, which is pricey. Again, some of that comes down to the brand and build quality. This unit also has smart home tech, so I can see how much time is left on a cycle on my phone, and get notifications when it’s done. I’ve actually linked mine into my broader smart home so a light in the kitchen goes green when a load is done. There’s also an announcement that’s played on our Homepods. Necessary? No, but it’s really handy to keep the laundry moving.
For comparison, the LG heat pump dryer I mentioned earlier costs around $1,100. The GE combo unit retails for around $2,900, but again, that’s including a washing machine as part of it. And the LG stacked combo, which also has a washing machine, retails for around $2,300. For comparison, one of the better selling dryer models out there, the Samsung I mentioned earlier, retails for between $700-$900. You can also find very affordable, not energy efficient, electric dryers for $500-$600.
Is it worth the price premium for a heat pump model? It depends on your goals. If you’re just trying to save money, then it depends on the electricity costs in your area. The Miele (and other heat pump dryers) are around 133 kWh4 vs. something in the 600 kWh range. As I mentioned, in my area that could mean about $140/year in savings. Comparing the Samsung to the LG model that costs $1,100 would take about three years to equalize. The Miele would take about eight years to equalize. There’s definitely an upfront price hit you take going this way, but the standard electric dyer we used at my old house was 17 years old and still going strong. I’m expecting this Miele to do the same, which means a pretty significant savings over that time span. But the part that’s hard to equate in this is how much energy is lost from vented dryers … just from energy loss through that vent.
At the end of the day, my wife and I are happy with the Miele dryer. It’s got some quirks that take getting used to, but for the two of us it’s working size-wise and energy-wise. But if you have a large family and need more capacity, I’d look elsewhere at something like the combo units from LG or GE. Regardless of the brand, make, or model, the genius engineering of heat pumps into our appliances like this really seems like the future of all dryers … and it’s why it’s one of my favorite new pieces of tech in my home.