experiment: $6 swampcooler

This spring I was in a walmart somewhere and saw a Pelonis 1 gallon humidifier on clearance for $6. Walmart usually has the worst clearance prices so I was surprised to see it for 75% off.

This was interesting because a swamp cooler and humidifier of this design are doing the same thing: blowing air through a wetted, porous medium. The goals are different (humidification vs cooling) but the mechanism is the same. The closest analog I saw on Amazon was this one.



Note: I tested power first because it takes a while for the pump to start moving water and the medium to saturate.

The label carries a power rating of 18w. Measurements with a kill-a-watt showed

  • LO = 7.5w
  • MED = 11.1w
  • HI = 15.9w

In this kind of device the water pump runs at constant rate; the selector switch only changes the fan speed.

If we can interpolate from my bigger cooler’s 60w/176cfm fan this one would be ~47cfm.


The test was performed when the interior of the van was 84°F (heat spike today in Los Alamos) with 16% RH. The air was coming out of the humidifier at 63°F.

A 21°F delta feels good when it’s blowing right on you (see below). It’s not going to cool the interor of a vehicle.

Output was too small to budge the measured RH inside the van.


It’s not sold as a swamp cooler but it works like one. But there are some drawbacks that will make it impractical for most people.

  1. the cfm (and therefore cooling output) is very small. I’d say it’d need to be a foot away to feel substantial cooling.
  2. the cooled air comes out the top, entirely reasonable for a humidifier but not so great for a cooler. One might make a cardboard shroud to redirect the cooled air horizontally. In the pic to the right I propped up a clipboard over the exhaust as a test. It worked but air escapes on the open sides. A full shroud would fix that.
  3. it is intended for stationary use and the top section just sits on the lower section. If someone were actually going to use it they might want to duct tape the bottom/top halves to keep it from separating unintentionally.

But for $6 with the above mods it might be useful in very dry areas for cardwellers or folks who want it close to blow over them while sleeping.


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