What Exactly Is A “Swamp Cooler”? And Do They Work?

okc hvac

What Exactly Is A “Swamp Cooler”? And Do They Work?

As June begins to give way to July here in Oklahoma City, temperatures are steadily climbing—and so are our energy bills. If you’re like a lot of homeowners, you might be researching ways to keep your cooling costs manageable. At some point, you’re likely to come across a promising option with an odd name: the swamp cooler.

What’s a swamp cooler?

Swamp coolers, otherwise known as evaporative coolers, are a simple, efficient, cost-effective, and environmentally friendly way to keep some homes cool. We’ll get to that “some” in a bit, but first let’s talk about sweat.

Yes, sweat.

When our body temperature starts to rise, our sympathetic nervous system cues our sweat glands to go to work. While different parts of our body release different types of sweat, it all serves the same purpose: to cool us down. As our sweat evaporates from our skin, it takes some heat with it (we’ll spare you the physics lesson), and that helps decrease our body temperature.

Evaporative coolers, which are about the same size as a room air conditioner, work in a similar way:

  1. Warm air is drawn into the unit from outside.
  2. The air passes over water-saturated pads.
  3. Water evaporates into the air (again: physics), and cools it down.
  4. A fan pushes the now-cooled air into the room.
  5. Warmer air in the room, displaced by the cool air, is pushed outside.

How is a swamp cooler different from an air conditioner?

Standard air conditioners recirculate the same air continuously, while evaporative coolers rely on a steady supply of warm, outside air. In addition, swamp coolers don’t typically use a duct system like central air conditioners do. Instead, air is directed to different parts of the home by opening and closing doors and windows.

Third, air conditioners require some type of refrigerant to cool the air, and  those chemicals tend to be tough on the environment. By contrast, evaporative coolers need just one liquid: water. (Granted, that’s a point in the con column for drought-prone regions.)

Perhaps the most encouraging difference between the swamp coolers and air conditioners is cost—both to install and operate. Evaporative coolers are much, much less expensive to purchase and install, and, on average, they use about one-quarter the energy required by traditional AC units, according to energy.gov.

So, why are swamp coolers only good for some homes?

Here’s when we may disappoint you: Swamp coolers are only effective in dry climates. (Sorry guys- that means they won’t really work here in OKC.) Since they work by adding moisture to the air, already humid environments may just get stickier, rather than cooler.

To determine if a swamp cooler could make a significant difference for you, you’ll need to figure out two things: the wet bulb temperature and the dry bulb temperature. Determining the dry bulb temp is easy; just take a look at your thermostat and write down the current temperature in your home. The wet bulb temperature is how warm or cool it would be if the humidity were at 100%. To simulate those conditions, simply cover a thermometer with a wet cloth sock, and run a fan across it.

Now, calculate the difference between those two, which is called the wet bulb depression. An efficient swamp cooler can bring down the temperature by as much as 95% of the wet bulb depression. As the web and dry bulb temperatures get closer and closer (and they will, the more humid the climate), the swamp cooler’s effectiveness decreases dramatically. In general, if your web bulb temperature is higher than 70ish degrees F, you’ll be bummed by your results.

What sort of maintenance do swamp coolers require?

Here’s another reason to hesitate about chucking your OKC AC in favor of an evaporative cooler (aside from the fact that, like we mentioned earlier, they won’t really work here): they require a good deal of maintenance. You’ll need to clean or change the pads at least monthly, or they’ll begin to stink—which is likely where evaporative coolers earned their swampy nickname.  You’ll also have filters and a pump to contend with, and you’ll need to clean and scrub the reservoir periodically, because the evaporation process leaves behind mineral deposits that can damage the unit over time. Finally, some evaporative coolers are installed on the roof, so you’ll cause wear and tear to your home as you do your monthly maintenance.

How can I be sure if a swamp cooler is right for my home?

Like we mentioned earlier- swamp coolers aren’t really an option in this area. We’ve helped OKC homeowners with their non-swamp cooler HVAC needs for years, and we’d be happy to help you, too. Give us a call today!

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