Design and features

• Relatively compact for a powerful portable AC
• Air con, dehumidify and fan modes
• Remote control, app control and smart home support

The ProBreeze OmniCool 12,000BTU (3.5kW) portable air conditioner is a three-in-one unit that can cool rooms of up to 35m² – there are smaller versions (down to 5000BTU) and larger versions (up to 14,000BTU), but crucially, these aren’t focused on quiet performance like the OmniCool is – keep that in mind a little later. If you want the quietest AC in ProBreeze’s collection, this is it. 

Having used 12,000BTU portable AC units in the past, I was pleasantly surprised by how compact the OmniCool was when getting it out of the box. It’s wide, but it doesn’t protrude that far, measuring in at 440 x 350 x 740mm, with an angled vent at the top that rotates in use and automatically closes when not in use, helping keep the outlet free from dust – and making for a cleaner overall look.

As with most AC units, it’s mounted with casters to make it easy to move around. That’s definitely a good thing here, as the unit itself weighs a not-insignificant 28.5kg, which can make it a challenge to get it up flights of stairs. Still, there are handles on both sides to help with grip.  

And, like other portable AC units, there’s a hose on the back that’ll need to be vented out of the window – it essentially expels all the hot air from your room.

Thankfully, ProBreeze includes a few options to help create a seal around the vent and stop hot air from coming in and cool air from going out – the problem of negative pressure that all portable AC units suffer from. You’ll find a sliding bracket for sliding windows, along with a more flexible material venting kit that sticks to casement windows. The latter worked best for me in my office.  

You’ll find controls front and centre on the AC unit, though it also comes with a remote and app support. 

In its cooling mode, you can adjust the temperature, fan speed (with three modes to choose from), and outlet oscillation. There’s also a fan-only mode with the same controls, and a dehumidifier mode that, thankfully, doesn’t require a permanent drainage hose, unlike some cheaper units (moisture is sent out of the hose through your window or door). 

You’ll also find the staples of the portable AC experience including a timer, which goes up in one-hour increments up to 24 hours, along with a sleep mode that’ll sightly raise the temperature overnight to adjust for your drop in body temperature as you sleep. 

The bundled remote comes with its own screen, helping you manage the mode, fan speeds and other settings without seeing the screen on the AC unit itself, but it doesn’t use Bluetooth to sync – and that can cause issues. 

If you exclusively use the remote to control the AC, it’ll be fine, but if you use the remote, then change something on the AC unit itself, the remote won’t be aware of those changes – and it can cause it to become unsynced and, well, a bit confused. As such, I much prefer to use Alexa (or Google Home, if that’s your thing) to turn it on and off, and the ProBreeze app to change the mode settings.

The app can be a little clunky to use at times – I’d rather have full AC controls on the AC’s homepage in the app, but you first need to tap Remote to access that functionality – but it generally works as expected and gives you breakdowns on things like average temperatures. 

Performance

• A-rated with a 2.6 EER
• Great cooling capabilities
• More granular dry mode settings would be nice

Despite the massive 12,000 BTU output of the OmniCool, it’s an A-rated appliance, consuming 1.35kW of power for a cooling capacity of 3.52kW. That makes for an Energy Efficiency Ratio (EER) of 2.6, which is pretty solid for the output, although a way behind the 10,000 BTU De’Longhi Pinguino 100 Silent, which has an EER of 3.57,

However, I found it never hit those heights in actual testing. Even with the AC running on full power, it’d peak at around 1.25kW before settling into the 1.15kW range, suggesting slightly more efficient performance.

Of course, it all comes down to the actual performance – no point in getting excited about energy efficiency if it doesn’t actually cool the room – and I’ve been pretty happy with how the unit has performed over the past month or two of use. 

With a 12,000 BTU output, the OmniCool can cool spaces up to 35 metres², so it makes relatively light work of my outdoor office in most conditions. My outdoor office is exposed to the sun for most of the day, and even on relatively cool days, temperatures can climb. And, during the current UK heatwave, it’s hitting highs of nearly 40°C inside, despite having curtains and doors closed. 

However, running the OmniCool for around 45 minutes brought the internal temperature down to a much easier to manage 26°C – though it could never quite bring it down to the 25°C target I’d set, meaning it stayed on full power for the entire 45 minutes – a cost of just under 23p using current energy prices. 

That is an extreme example, of course, and with regular summer temperatures in the mid- to high 20s, the ProBreeze does an excellent job at bringing the temperature down and keeping it there, usually taking 10-15 minutes to noticeably bring down the temperature before switching to a fan mode that sips just 20-50W of power when not in active cooling mode. 

On some occasions, however, I’d find it not quite as successful at reducing that hot feeling I had – though I soon realised it was more down to the humidity of the room rather than the actual temperature. 

Thankfully, with a built-in dehumidifier, the OmniCool makes light work of reducing moisture in the air. The catch is that, unlike the regular AC mode that can go up to full power fan settings, the dehumidify mode is stuck on the lowest speed setting, so it doesn’t feel quite as immediately impactful. 

I do wish that there was some kind of icon that’d let you know when there’s high humidity detected – there’s a temperature gauge for current temps, but nothing else – and I also wish that I could specify a level of humidity to aim for, either on-device or via the app, but that’s also not available here. Instead, it’ll run at full power until it detects that humidity has dropped, then switch back to a regular fan mode until it’s needed again.  

Still, it can do a great job at making the room feel drier – and that’s arguably just as important in high-humidity heatwaves like those we’re currently facing in the UK. And, with an internal evaporation system, you’ll only ever need to manually empty it on the most humid of days. I haven’t needed to yet, anyway. 

What impresses me more is the sound – or lack thereof, really. Considering the size and output of the AC and my past experience with big, bulky AC units, I expected it to make a racket, especially at full power in cooling mode – but that wasn’t really the case. 

Sure, there’s some noise, and you’ll probably have to turn the TV up a bit if you’re watching something, but it’s more the sound of the air rushing out than the rattle you get with some AC units.

I measured just over 55dB in its cooling mode at the lowest fan speed and closer to 61dB at full fan speed, while it’d drop to around 48dB when on its fan mode – louder than a fan for sure, but much quieter than some high-output portable AC units. 

Should you buy it?