What About Those Portable ACs?

Photo by Galvão Menacho from Pexels

Every few days, I see someone on a vanlife or mobile living forum ask about the portable personal air conditioners that are advertised in corny As Seen on TV type ads. Some are plugged into the wall, others are powered by USB.

If you are contemplating the summer heat in a van, boat, or another tiny dwelling, they can seem like a godsent. After all, they are cheap, small, and low-power.

The problem? They don’t work.

How a Mini Air Conditioner Works

Mini air conditioners are actually evaporative coolers. Inside their shells, they have a chamber where the user adds ice or water, and a fan that blows across that. The water evaporates as the fan blows, which makes the air that comes out the other side colder.

This type of air conditioning has existed for some time. In ancient Egypt, people would hang wet blankets across doorways to cool the breezes that flowed inside. In modern times, homes in dry regions are often cooled with swamp coolers, rooftop appliances that use water to cool air pumped into the home.

The drier the air, the better this works. This is why one in four homes in the Rocky Mountain region is cooled with evaporative cooling. In an area like that, it is cheap and effective AC.

But, the opposite is true, as well: humidity affects how effective your evaporative cooler will be.

Why This Is a Bad Thing

In a hot, humid state like Florida, you are already dealing with average humidity that hovers around 74.5%. This means that, on an average day, the air is already holding about three-quarters of the amount of water it possibly can. There just isn’t space for any more.

Add to that the conditions you face in a small space like a van or boat. In a confined space, excess moisture is an ever-present enemy. Your own respiration continually adds moisture to the air. Just sleeping, you’re pumping around 40 grams of water vapor into your environment every hour.

Your belongings are often crammed all together in ways that they aren’t when you are in a larger dwelling. One of the biggest complaints I see from liveaboard sailors is that we are always finding new patches of hidden mildew and mold.

An evaporative cooler is going to just add more moisture to this environment. Not only will it not work well enough to cool you. It’ll leave you damper than the humid summer air did in the first place.

A Caveat

I could see these cooling you enough for comfort in certain circumstances. If you happen to be in a very dry region and have adequate ventilation, the cooled air they blow directly on you could be enough for comfort. They’d operate like a personal version of those misting fans that many outdoor restaurants and bars set up in summer.

However, I just can’t see relying on those for your air conditioning needs in most environments. If you are in a region where you need to plan how to keep cool, you need other solutions.

Better Options for Staying Cool

So, how do the vanlife and boatlife folks battle the heat? These are a few methods that work for me:

First, I currently stay in marinas during the hottest parts of the summer. There, I have shore power that I can use to power a traditional coil air conditioner.

At anchor, air flow is key. I open up the hatches and make sure that a good breeze comes through at all times. Tools like wind scoops help concentrate and direct air flow.

Hand fans can be a life saver. I bought an assortment of wood and silk fans and usually have one nearby to cool down.

Drink plenty of water. Add a slice of lemon or cucumber if you aren’t a fan of drinking it plain. Avoid sugary sodas. Too much sugar plus too much heat is a recipe for a headache.

If you want to drink alcohol, stick with dilute, not too sweet drinks. I like to refresh with a Michelada or a shandy.

If you have a cooler or refrigerator, keep a wet washcloth in a ziplock bag. You can run it across your pulse points or the back of your neck when you need to cool down.

Final Thoughts

Heat can be a serious issue. Beyond factors like comfort, too much heat can actually be dangerous. If you are taking to nomad life, figuring out how you’ll deal with temperature extremes is important. But, no matter how cute and inexpensive they are, stay away from the evaporative coolers.

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