There are plenty of hot days over the Aussie summer and without a cooling solution, it can get pretty uncomfortable. The Zero Breeze Mark 3 was launched at CES 2025, and I got my hands on the Zero Breeze Mark 3 just at the tail end of the season, with some warm days and nights lingering.
What is the Zero Breeze Mark 3? In short, it is a portable air conditioner designed primarily for outdoor use. But as we will find out, it is not necessarily limited to that.
The specs boasts a cooling capacity of 5,280 BTU (British Thermal Units), suitable for space from about 9.2 square metres to 14 square metres and maintaining a temperature between 16 C to 31C.
What is important in a (portable) air conditioner?
It is always foundational to go back to basics, where cooling capacity is key. It is critical to match the correct size unit to the correct task. Undersized units will struggle to deliver, and oversized ones can waste energy and cycle inefficiently.
In the case of a portable air conditioner, where you are likely to have the unit in close proximity, noise levels under load are something for serious consideration. Other factors include size, weight, build quality, flexibility and drainage.
First Impressions
The Mark 3 comes as a base unit, which is the base air conditioner with a pretty hefty 50V DC power adapter to go into a general purpose outlet (GPO).
There are some key components that comes in the box with that:
- drainage pipe
- inlet ducts
- outlet ducts
- inlet adapters
- outlet adapters
It also comes with an IR remote controller.
The Mark 3’s air-conditioning unit is a sealed unit containing a fluorinated gas, and does not support user-refilled refrigerants. This is strictly a job for a certified technician.
The base unit can be powered via a GPO, car cigarette port, a generator or solar. Essentially whatever will work as long as it meets the power requirements. Other than the GPO method, the connectors for the other options are not bundled in together.
To make the Mark 3 truly portable, you can add batteries to the unit. The manual says you can chain “2, 3, 4 or more batteries”, but my research suggests that four batteries is pretty much the limit.
Getting Started
The Zero Breeze Mark 3 is not really a point and go device if you want the best results, but you can be up and running fairly quickly.
First point to note here is that Zero Breeze instructs users to leave the Mark 3 on a flat surface for a minimum of thirty minutes before turning on – particularly if it has been in transit. It is also important for proper operation, for the Mark 3 to remain level and on a flat surface, not tilted. The manual also calls out explicitly to not operate the unit upside down.
If all you want is spot cooling – blasting some cool air directly at yourself, then all you need to do is to position the front outlet at yourself and fire up the Mark 3. There is no ducts or installation required in this mode. You don’t have to be outdoors for this, but for a few good reasons this is highly advisable.
Firstly I assume most people would not want the drainage water just running over your floor indoors. Secondly like all air conditioners, you need an outlet for the hot air to be expelled away from the cooling zone.
So if you are trying this in an enclosed room, depending on the size, you might just find it heating up rather than cooling down.
This brings us back to basics: the efficiency of changing an enclosed space’s temperature is directly related to energy input versus room volume. Think of using a household fan in a gymnasium, there will be negligible effect. Conversely, put a gym-sized AC unit in a single-car garage and it’ll be freezing in no time.
Mathematics
Going back to the specifications. The Mark 3 boasts a capacity of 5,280 BTU. The British Thermal Unit is a measure of heat (as energy), and was originally defined as the amount of heat required to raise the temperature of one British pound (naturally) of water by one degree Fahrenheit, at a constant pressure of one atmospheric unit.
Without diving into all the mathematics behind the scenes, 5,280 BTU is equivalent to about 1.55 kW. Kilowatt is typically the unit used to quote the cooling power of a split air conditioner. The bigger the number, the more heat can be removed from the room and the bigger an area it can service.
The Mark 3’s rating is calculated to suit an area of about 9 to 14 square metres, which is bang on what Zero Breeze quotes in their specifications. This converts to a room range of 3×3 m to 3.74 x 3.74 m. That is a fairly confined space – interior of a tent, car cabin, small RV, study or small bedroom typically.
In an ideal world, the cooling curve would be linear—cold air in, hot air extracted, everything operating at optimal efficiency, governed by principles like enthalpy. But of course, the real world is far more complex. Several factors affect performance, including ceiling height (remember, hot air rises and height increases volume), sunlight exposure, the number of people in the space, the quality of insulation, and how many devices are generating heat.
Ever entered a restaurant before the dinner rush and found it chilly, only for it to warm up as more people arrive? The settings didn’t change, your body heat and everyone else’s made the difference.
In Use
Could I have conducted objective, scientific testing? Sure. But I live in a regular house, not a controlled lab. That makes repeatable baseline testing impossible.
What I do know is that there are a couple of rooms at my place that can get stuffy and warm on sunny days, and fans do little more than circulate hot air. It was the logical place to give the Mark 3 a good run, but it didn’t come without challenges. Just how should I set it up?
Firstly don’t forget to attach the drainage tube, unless you really enjoy mopping up water or drying out carpet. Make that the first thing you do when setting the Mark 3 up.
For best performance, you want the hot air to be ducted as far away as possible from the cool zone to facilitate heat exchange. With the duct system you have a variety of possible configurations depending on your space. You could place the Mark 3 inside or outside the enclosed space, you could fit the various inlets and outlets to direct cold air, hot air, ambient air etc. This is a good time to refer to the instruction manual to assess what would be best for your needs.
The test bedroom is about the optimal range of the Mark 3.
My challenge comes in the form of a window that is mounted on the top half of a wall, of the old style winding chain type so it creates a slant opening. There is no flat platform I can use to lift the unit closer to the window, and because it’s essentially on the second floor I can’t explore the option of putting the Mark 3 outside. So it was down to making use of the ducts.
I needed to install an outlet adapter and attach a duct to it, run it up the wall and point it out the window as best as I could. That part was manageable with a bit of ingenuity and the help of a chair.
The bigger problem I had was getting the duct to stay put with the adapter. It was an exercise in frustration when I am already sweating. That was until I pulled off the adapter and worked out you can just mount the duct by screwing it in once it is aligned properly. This mistake is on me.
Zero Breeze also includes some blanking plate with pre-cut openings so you can better keep hot air away if it suits your window or vent opening.
With all that done, I only needed to ensure the drainage pipe outlet sits in a bucket and I was ready to fire it up. It amuses me that the rear of the Mark 3 has a red LED strip (when powered off) not unlike a brake light in a modern car. When it is running, the LED is blue. It makes it easy to figure out which end is which.
The Mark 3 has a few operational modes:
Rocket Mode: Run at maximum cooling capacity with power between 350 – 500W
Cool Mode: Run at moderate cooling capacity with power between 200 – 350W
Sleep Mode: Lowest cooling capacity with power between 150 – 200W
Fan Mode: Fan only, power between 12 – 18W
Dry Mode: Remove excess humidity, power between 350 – 500W
Care Mode: Keep air flow from the outlet at constant tempeature, power between 150 – 350W
Heating Mode: Increases temperature by up to 6.5C (note the manual says it is up to 20F which makes it -6.6C)
For me, the priority was to cool the room down to a more comfortable level before the kids bedtime. So it was rocket mode to get things moving. After that it was to maintain the temperature for comfort.
Is the Mark 3 a miracle gadget? Hardly. The laws of thermodynamics and physics are immutable. The further you can separate the cool and hot air, the better the result within the constraints of the cooling power of the unit.
In the less than optimal set up that I can do in the bedroom, the results were pretty average. This was due in not small part to the inability to properly vent the hot air away from the room. It left the Mark 3 to essentially compete against the ambient room temperature and itself in an attempt to cool the room down.
In a different room where I had better control over the hot air venting, the Mark 3 is a little more effective at it’s job. Admittedly this is a room that is half the size, but it has a large exposure surface to sunlight. The temperature change is not dramatic, with more like a slow decrease over time that is hard to track if you are staying in the room with the unit the entire time.
In either scenario, the Mark 3 is noticeably much more efficient if you are standing in front of the cool air vent. A small tent designed for 2.5 or three people, or a standard car cabin, is pretty much the ideal space for the Mark 3. Both of these situation would generally have substantially small volume of air to displace compared to a room in a house.
Heating
The data on using the Mark 3 as a heater is a little confusing. In one section it says increases the ambient temperature up to 20F. Well I don’t know about you, I suppose an Eskimo would think -6.6C is warm.
In another part of the manual, the unit allows you to set it up to 28C on the controller. And in another literature, it says it can top out at 31C.
Fact is, it is a lot easier to heat up a room than cooling it down. Whilst the Mark 3 is not a dedicated heater, but 6:30am on a cold autumn morning setting up your stall at a Sunday market, walking in front of that blast of hot air is the closest thing to heaven on earth at the time.
Noise
When you are practically going to bed with the Mark 3, the noise level becomes an important parameter. Unlike split units where the noisy bit goes somewhere well, the furthest the Mark 3 can be away from you is limited by the length of your duct.
Rated at 46 decibels when running, the Mark 3 is just 6 decibels above the average suburban area at night (40 dB) and quite a bit quieter than the average domestic refrigerator (55 dB). However, for a noise sensitive person, having the Mark 3 running in the bedroom whilst they try to sleep was a no go zone. In the dead of the night quietness, tit was just a noise they could not handle.
Personally, noise doesn’t bother me, I can sleep through almost anything. Most of the time the heat doesn’t bother me either.
Battery
Depending on your usage, each external battery will give you between two to eighty-five hours of run time. The best rated battery capacity is seven hours if the Mark 3 is used in the lowest cooling capacity.
As mentioned earlier, you can daisy chain up to four batteries concurrently to extend the running time.
Speaking of batteries, each one has a sturdy loop on the side for carrying.
Size and Weight
The Mark 3 base unit weighs in at 10kg. The top of the unit has a built in handle which makes it simple to pick up and move around.
Dimension wise it is 56 x 26 x 31 cm (LxWxH) which is relatively compact overall, but not a throw it in a bag kind of small.
Each battery pack adds 6.4kg and 11cm height to the overall size (51 x 21 x 11cm). If you are fully loaded at four batteries, then you are looking at a good 35.6kg total.
Other Features
A cool touch (pun intended), is that the air outlet has a breathing light around it. The colour of the light reflects the temperature at the air outlet, from 16C (blue) to 28C (red). It gives you an at a glance indication of what the Mark 3 is doing.
There is a small screen on the top to give you a digital read out as well, so you are not just guessing by the breathing light colour.
It also comes with a handy remote control which gives you complete control over the unit. You can even child lock it so your little ones can’t play around with the settings.
Gripes
It’s one of those rare occasions where I really do not have much to complain about. I suppose if I want to nitpick, the unit has quite a footprint especially when you are packing a car full of gear or merch. The ducts also add more bulk on top of that.
As much as I love some creature comfort, especially at the Sunday market, there’s not always space in the car alongside the merchandise.
The charging brick is huge, but that said, there is a fan built into it. You can hear it when you plug it into power.
Conclusions
The Zero Breeze Mark 3 is a portable air conditioner aimed at specific use cases – like cooling a tent, RV cabin, or vehicle interior. After all, who wants to idle the car just for climate control?
It is not a substitute for a proper household air conditioner. In those scenarios, it only really helps if it is blowing cool air directly on you.
That said, for heating, it is quite effective. I have used it to warm the bathroom for the kids, without heating the entire house.
The Zero Breeze Mark 3 base unit has a RRP of A$1399,99 but at the time of publishing discounted by $100 to A$1,299.99.
Each battery pack is valued at A$899 as a standalone buy, but if you bundle a single battery with the base unit, it’s on sale for A$1,899.99 or for two batteries A$2,499.99.
It is not a small amount of money to outlay, and whether you take the plunge really depends on how much you value your creature comfort where ever you go. Reality is that camping gear are rarely cheap, and cheap camping gear are rarely good or reliable. I think back to some of the summer hikes that my younger self has done, the Zero Breeze Mark 3 would have been a godsend.
DRN would like to thank Zero Breeze for providing the review unit.
