The Inspecting Evaporative Coolers/Swamp Coolers article reviews external and portable systems and distinguishes what needs to be inspected and does not need to be inspected.
Good article, but there are a few mistakes. I am not familiar with the terms latent and sensible heat, so maybe I have misunderstood the terms and applications. From the linked article:
“The ability to make something feel cooler is called latent, and the measurement of something cooler is called sensible cooling. Adding cool, moist water vapor to the air will make the space feel cooler and, in certain cases and applications, is a more cost-effective cooling method. This is why misting systems are added to certain commercial properties. The moist air feels cool on the skin.”
The primary advantage that ECs employ is that when the water evaporates, it’s change of state from a liquid to a gas absorbs heat, thus cooling the air. This is similar to the principle that an AC system uses.
The reason misting systems work is that the water mist is still a liquid, and whatever it happens to land on, and then evaporate from (latent heat of evaporation), gets cooled as it goes into a gaseous state. Also, as the tiny water droplets fall, they are evaporating, thus slightly chilling the droplet(s) having a conductive cooling effect. Yes, the air directly below a mister is slightly cooler, but for a mister in a dry climate, that is a secondary effect.
The Explainer section is confusing, while the evaporative principle is touched upon later in the How section.
ECs do, as the article states, also moisten the air (gaseous form) which depending on the exterior humidity levels may help make it ‘feel’ cooler, however this is secondary to the cooler air temperature.
Portable EC units are infrequently used, as they are not that effective. Placed inside a structure with closed conditions, the constantly evaporating water increases the humidity, which subsequently lessens evaporation, lessening the cooling effect to close to zero after high humidity is reached. Building solar heat gain will still occur, and coupled with the high humidity actually makes the interior more uncomfortable than if nothing was done. Placed in a building opening (like a doorway, or garage bay) with an open building condition, drawing in dry air, there is a large area for exterior (hot summer) air to intrude which is very inefficient to say the least.
It might help people unfamiliar with this type of cooling system to think of them as whole house fans, plus plumbing. I have never heard of an EC being referred to as ‘external’. External AC condenser? Yes, but a necessary descriptor? Additionally, I have never seen a sprayer used to wet the pads, that would lead to… I suppose it is possible, but to prevent resultant problems system modifications would be needed.
There are more than a few additions I would make to the Common Concerns section.
Thanks for your feedback. I changed external to permanently-installed in the article. Hope that clears up any confusion. What additions would you add to common concerns?