Bests & Worsts Reviews from Amazon

I am rather torn about writing this review. On the one hand, the unit really does work as a proper air conditioner, it has two separate air circuits, one that sucks in room air, cools it, and expels it into the room, and another one that sucks in outside air, transfers room heat to that air, and expels the hot air back out. So it’s different from all these cheap units that use either evaporation or an ice reservoir to cool. But the problem start with the fact that the indoor cooling circuit and the outdoor heating circuit are too closely together, limited simply by the size of the device. This usually leads to a decrease of efficiency, and as I calculate it, the unit has only around 10 SEER (which are basically cooling BTU per hour divided by electric Watts used, with a few adjustments for the effects of seasonal changes), so 2300 BTU/h (their claim) divided by 240 Watts (their claim, and verified using a Kill-A-Watt by me). So as ACs go, 10 SEER is not much at all these days, and it may even be less since we have to trust their 2300 BTU/h number for that. However, it is very difficult to do better in such a small device because of the small separation between “hot” and “cold” circuits, and furthermore, in a small unit, losses in ducting and surface heating are exacerbated compared to a big unit, just like kids get too cold or too hot quicker than adults because their surface area divided by body weight is higher. So this brings us to how the device is powered. The 240 W it draws running at high capacity is not a problem for a wall outlet; however, their unit operates at 24V, so a heavy (and cheap looking) transformer is needed. That transformer itself is not very efficient, it gets quite hot during regular use, and in fact if kept in the same room, heats the room right back up and denies some of the gain of the AC. The unit I got also has a battery, which is quite hefty at I think 840 Watt hours. But even this big battery can only power the device for roughly 3.5 hours at max power. But then, there is no way to even recharge the battery without shutting off the AC, since the hefty power brick can handle either the device or the charging of the battery, but NOT both at the same time. For this the size of the brick would have to be doubled, which would make it heftier yet, and produce yet more heat that the weak AC would then have to remove. I actually set out on an experiment, trying to cool a very small spare bedroom on the north side of the house that has only a small window, to see if the Zero Breeze Mark 2 could handle it. One of the uses I had bought this unit for was during power outages when the whole house AC would not run, and the unit would be powered by a large “solar generator” battery, which during the day is re-charged by solar panels or a gasoline generator. I sealed off all the regular AC ducts for the room, and running it for a few days, I can confirm that it actually sort of works, even in a typical Florida summer. Running it continuously mostly on high power, it lowered the temperature by about 10 F, and equally importantly, it removed huge amounts of water from the room, roughly about one gallon per day. Overall it made the room somewhat comfortable, and definitely to the point where one could sleep and live in that room while waiting for “real” power to come back; yet at the expense of a pretty high operating noise. The other use I had planned for the unit was during car or RV camping. But the first problem is that it’s also not really possible to either re-charge in the car, or even operate the unit continuously from a regular car battery, even if the car were running to keep the main battery charged. The typical car cigarette lighter plug is only rated for about 10 Amps, which at 12-13 Volts means less than say 150 Watts. There isn’t much one can do in that plug design, otherwise the connecting tip gets way too hot. So, a specialized setup would be needed, ideally with wiring directly to the car battery and involving a step-up DC transformer from 12V to 24V. And all that only really works once the car is running, since the useable capacity of a typical car battery is a bit less than the capacity of the Lithium Ion battery the Zero Breeze ships with. So you would need a hefty extra battery bank as it is found in RVs or camping trailers; but the unit itself is too weak to cool the entire trailer or RV even at night when there isn’t external solar heat load, so an area has to be curtained off. And then that still leaves the need to route the two ducts for the outside air, which becomes very cumbersome and clunky looking in a hurry. So overall, yes, from a scientific perspective, the unit works, and it works just about as well as it can, given its size and power constraints. It also has a very appealing design, at least compared to other HVAC equipment. But overall, while the manufacturer has done a good job pushing physics to its limits, it’s not quite enough to result in a practically overly useful unit. So, with mixed feelings, I sent mine back in the end.