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 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. 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. 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. But even this big battery can only power the device for roughly 3.5 hours at max power. The unit I got also has a battery, which is quite hefty at I think 840 Watt hours. 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 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. So this brings us to how the device is powered. 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 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. 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). 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. So it’s different from all these cheap units that use either evaporation or an ice reservoir to cool. 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. I am rather torn about writing this review.
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