EcoAir Crystal MK3 Portable Air Conditioner review: tested during a heatwave

Price on writing: £250 | Buy now from Amazon

How we tested

Mumsnet editor Poppy tested this portable air conditioner in her WFH office during a heatwave in June. Taking detailed notes on set-up, effectiveness and quality, she tested all the unit's functions over the space of two weeks.

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Our verdict

With temperatures hitting 30°C already this summer, portable air conditioners are becoming more and more popular in the UK. They're called portable because they don't require permanent or professional installation. When summer ends, you can wheel it away into a cupboard or, in the case of the EcoAir Crystal MK3 Portable Air Conditioner, start using it as a dehumidifier to help dry laundry indoors.

In order to function properly, portable air conditioners do need to be vented out of a window. The EcoAir Crystal MK3 comes with a window kit included (not all air con units do), suitable for any type of window.

Setting it up is quite straightforward, if a little fiddly, and there's a helpful instruction booklet included. Once vented, the air conditioner is ready to roll, and it gets to work quickly cooling rooms up to 26sq m.

The air conditioner cools the room effectively and quickly, it started to feel more comfortable in my stuffy WFH office within a minute or two. Without a sleep mode, it is a little noisy, but it certainly takes the edge off during a heatwave.

At £250, it's a great price for a 9000BTU machine. Its double use as a dehumidifier makes it even better value for money. I'd definitely recommend this air conditioner to those looking for an effective way to cool their home in hot weather, without breaking the bank.

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How easy is the EcoAir Crystal MK3 Portable Air Conditioner to set up and start using?

As with all portable air conditioners on the market right now, the EcoAir Crystal MK3 needs venting out of a window. It comes complete with a window kit that'll work on pretty much any type of window.

Setting it up is a bit time consuming and fiddly, but you only have to do it once. The Velcro can be left on your window frame (if you don't mind how it looks) and the plasticky zip up fabric can be stored away easily for the colder months.

First, I connected the venting hose to the air con unit. It slides into place - it's worth looking at the instructions for this part.

To set up the window kit, you'll need a pair of scissors. Roughly measure the Velcro tape along each side of your window frame, cutting and sticking them down as you go. No need to be 100% exact. Repeat on the edge of the window itself. The plasticky fabric sticks to the Velcro, creating a sort of zip-fly for your window. Post the venting hose through the gap, and zip the fabric up around the hose to create as small a gap as possible.

Once it's set up, the controls are straightforward. Controls are on the unit itself or on a small, light remote control. You can adjust the target temperature and fan speed, set a timer for it to turn off, or switch to fan mode.

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What's it like to use the EcoAir Crystal MK3 Portable Air Conditioner day-to-day?

My office felt cooler straight away, and I could see the temperature dropping after a few minutes on the unit's digital display. With 9000BTU, it's a powerful machine and didn't struggle to cool my medium-sized room.

The air conditioner has two fan speed settings but no sleep mode, and it is quite noisy.

I find the best way to use a portable air conditioner, if the noise bothers you or you want to use it in your bedroom, is to run it for an hour or so before you want to use the room. Close all the windows and doors and the air conditioner will turn the room into an oasis of cool. Then once you're ready to go to bed or start work, turn the air con off, keep the doors and windows closed and the room should stay cool for an extended period.

The remote control comes in handy for turning the air con off and on, or adjusting the temperature. It can also be used as a fan, for those days when it's not quite hot enough to justify having the air con on, but you still want a cool breeze.

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Does it work well as a dehumidifier?

The EcoAir Crystal MK3 also functions as a dehumidifier, which is a great selling point. As the UK doesn't get hot enough for air con that many days of the year, it can be difficult to justify a large-ish unit like a portable air conditioner. Using this one as a dehumidifier means you don't necessarily have to find somewhere to store it over the cooler months.

The air conditioner's instructions say the dehumidifier function (AKA 'dry mode') is for 'summer use only'. I contacted EcoAir to find out why this is, and they explained that the dehumidifier is a compressor rather than a desiccant. In a nutshell, this means the air it expels in dry mode is slightly cool, whereas a desiccant dehumidifier expels slightly warm air. So, using the dehumidifier function might make your room a tiny bit cooler, but this is true of any compressor dehumidifier, including Mumsnet's favourite model, the Meaco Arete One.

Unlike most standalone dehumidifiers however, the water tank of the EcoAir Crystal MK3 isn't removable, so you need to attach the drainage hose (included) either to empty a full tank of water or set it up to continuously drain into a bucket.

When using the unit as a dehumidifier, it's just as noisy as the air conditioning function, which isn't great for drying clothes overnight. However, it does the job and I'd much rather have one multi-purpose unit than two, personally.

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Does the EcoAir Crystal MK3 Portable Air Conditioner offer good value for money?

At £250, this is a great value air conditioner, especially when you consider the BTU rating and dehumidifier function. You can pay £400, £500 or even £600 for a top-of-the-range portable air conditioner these days, and units like the AEG Comfort 6000 will come with an app, more power and quieter motors.

But if you're looking for a portable air conditioner without the bells and whistles, that'll do a good job taking the edge off in a swelteringly hot room, I can thoroughly recommend the EcoAir Crystal MK3.

About the author

Poppy O'Neill is a Content Editor at Mumsnet and a mother of two. She researches and reviews the products Mumsnetters swear by, with a particular focus on home essentials, laundry and fans. From a highly-recommended retractable washing line to the best quiet fans money can buy, and Mumsnet's favourite dehumidifier to the steam generator iron that'll cut your ironing time in half, she loves to deep-dive into research and find the very best products on the market.

With an MA in Creative Writing and a PGCert in Lifestyle Journalism, Poppy's written about parenting topics for The Sunday Times, The Guardian, The Mirror and The Sun. She's a best-selling, award-winning author, and her books for children and parents have been translated into 12 languages.