If it requires a bottle of water, drink the water. Grab a magazine and fan yourself. Will work better.
Please do. Most of us are reading in the US.
I’ve had several of those, including the one in my living room right now. The older ones were crappy and loud, but the newer ones (especially with an inverter and variable compressor) can be both efficient and whisper-quiet. Instead of cycling on and off at full blast like the old models do, they can run quiet and slow and keep the room at the set temperature through the day. I keep mine running on the thermostat all day, all week, and basically never hear it. It’s about as loud as an electric fan on low, or maybe a bit quieter.
There can be a lot of difference between the bad, old ones, and the nicer, newer ones, though. Ratings are helpful, e.g. The 4 Best Portable Air Conditioners of 2026 - RTINGS.com or Best Portable Air Conditioners - Consumer Reports
And to be clear, these are the legitimate portable room air conditioners that actually pump heat outside, like this kind:
They are NOT the same thing as the likely scams (or shitty swamp coolers) the OP talked about.
Are you getting the ones where the supposed inventor always lives in your area, even if you’re in a tiny village?
I was intrigued as to why they think it’s a plus that the person breaking the laws of physics is local. It used to be that magical items were more believable if they came from far away.
Today’s BBC says the ASA are investigating - far too late of course.
As parts of the UK brace for another hot weekend, online adverts have been appearing for portable air conditioners claiming to be “designed by former Nasa engineers” and able to “cool a room in 90 seconds”.
The adverts have emerged on platforms including Facebook and YouTube, but the Advertising Standards Authority (ASA) has now warned the products are often “too good to be true”.
YouTuber Stuart Matthews, who bought several devices to test on his Proper DIY channel, told the BBC that despite paying £70 for one machine, it turned out to be “a small, simple fan worth only a few pounds”.
The BBC has approached Meta and YouTube for comment.
The ASA told the BBC that some of the adverts it had seen online in recent weeks made exaggerated claims, including that a small device could cool an entire home within minutes or used very little electricity.
It also said the adverts frequently featured fake customer reviews describing dramatic temperature drops or exceptional performance.
The adverts direct shoppers to websites selling the devices, typically for between £70 and £120.
‘Cool in 90 seconds’ - the fake portable air conditioners sweeping the internet - BBC News
The BBC just posted a report on this. Oh…ninja’d by bob_2…
’ 'Cool in 90 seconds' - the fake portable air conditioners sweeping the internet - BBC News ’
Maybe the latter has been overused; people make jokes these days about scams involving “Nigerian princes” and so on. Also, increasing xenophobia might make people more distrusting of things the farther away they are from.
Not that many, since I routinely use an adblocker, but yes.
He’s usually a maverick who invented it to save his father’s ailing engineering business, and turned down million pound offers from the ‘big AC companies’ because he wanted to keep it affordable for everyone.
I wonder how many of these things actually sell? Are people really that gullible?
Mind you, thermodynamics defeats a percentage of even science students, I guess…
Absolutely yes, people are that gullible and have been at least as long as we have written records.
As previously linked, we even had a thread here about it last summer asking how they could work.
To the extent there is a silver lining, it is that buying a massively overpriced fan should hopefully be an expensive life lesson rather than a devastating blow to most victims’ finances.
Where does the water condensate go? The unit that @What_Exit cited upthread says it comes with a drain hose, but confusingly, the description also claims “auto-evaporation”.
I found an ad for a very similar unit with a link to the user manual and it appears to answer these questions. Apparently it does its best to evaporate the condensate, presumably in the hot exhaust stream. But if it can’t keep up, or if it’s being used just as a dehumidifier, you need to attach the drain hose to the upper drain and put the other end in a bucket. Otherwise the water collects at the bottom of the unit and eventually it shuts off with an error code. That water needs to be drained into a drip pan through the lower drain.
Is that how yours works? Unless the auto-evaporation works really well it seems rather troublesome.
There’s at least three categories of these. The first category is things that technically work, in ideal conditions, and not very well even then. These are the swamp coolers and the ones you need to load with ice. The second category is simple fans that don’t cool at all, but they’re still at least (crappy) fans. The third category is the complete outright frauds, who will take your money and send you an empty box (that must have gotten damaged in transit), or nothing at all.
Here’s a very typical one.
Most of the portable units I linked to either have small condensate tanks that need emptying or a hose to go to a drain. Some people put the hose to a small pump so it can go out the window or to a sink drain.
Auto Evap could mean it send some of the humidity out with the hot air exhaust, but if it is just into the room, then it is failing to do the job.
Especially considering that for the purposes of a scam, you only need to target people more gullible than average not the majority of the population. If only, say, one in five people are gullible enough to be tricked, that’s still a huge number of targets.
The scammers usually operate on needing only 1-2% of the population to be that gullible.
I’ve got one of those, that we got several years ago when our heat pump failed and it was going to take several days to get it replaced.
Like you say, it’s on wheels so you can easily roll it from one room to another so you can have A/C in the room where you need it at a given moment. So it’s portable in that sense.
And as you also mention, you have to have a window handy to wherever you’re using it; it’s got an accordion-style duct to get the hot air from the A/C to the window.
Even those aren’t great. The problem is that accordian-fold duct. It’s not insulated, and the accordian-folding increases its surface area, so you’ve got a thin pipe of hot air running through the room you’re trying to cool. Most of the heat still goes out the window, but it’s still significantly less efficient than a conventional window-mount unit.
Yeah, if you want one room cooled all the time, the window-mount unit is your best bet. When we had to deal with several summer days without central A/C, we got window units for the two bedrooms, and used the portable for wherever we were downstairs.
The portable worked quite satisfactorily, as far as we were concerned, and cost about the same as a window unit, so it was a lot cheaper than buying window units for every room in the house. The duct was only a few feet long, so you did have to park the unit pretty close to a window, but that also meant that the hot air from the exhaust was out the window quickly. I don’t recall being able to notice that the air was warmer a couple feet away from the duct.
What a fantastic device! It needs no venting to the outside, draws almost no power, yet can cool a whole house or apartment in minutes! 
How does it work? The ad explains all!
The compact device draws in the hot, muggy indoor air and passes it through an internally sealed cooling chamber. A special nano-honeycomb filter strips the heat energy from the air at a molecular level
No mention is made of where all this heat goes, as required by the basic principles of thermodynamics. Apparently it’s just “absorbed” by the “nano-honeycomb filter”! This miraculous feat in contravention of physical reality is apparently made possible by the fact that the nano-honeycomb filter is “special”.
The ad also informs us that the inventor was offered millions for his patent by traditional A/C companies, but he refused because his mission is to provide a quality air conditioner to his fellow citizens at the lowest possible cost. He asks nothing more from life and I presume seeks his reward in heaven later on. In fact, he’s so dedicated to the cause that currently the device is going for 50% off (while supplies last!). You can click on a link to find out if this amazing offer is still available to you!
The only real clue to what this thing is beyond just a fan is in the FAQ, where there’s a question about how often it needs refilling with water, and the answer is that it has a large tank and will run for 10 hours or so on one fill.
So it’s actively blowing water into an already hot and humid room, and I assume that this “invention” is a swamp cooler in a nice case, making it worse than useless in any but the driest desert climate, and not very effective even there.
The hilarious pseudo-science in the ad is obviously designed to appeal to those who are simultaneously both ignorant and gullible. Naturally, it has many testimonials from incredibly satisfied customers!
Another factor is the type of window available. Ours are almost all horizontal sliders rather than double hung, and while there are window units available for that type I’ve found them to be prohibitively expensive. Only one room really needs a/c (it has a patio door facing west with no shade), and for that room a portable unit placed as close as possible to the exhaust window works quite well.