Dehumidifier Performance

Having ever so many books & papers in the Basement Shop & Office, I must run a dehumidifier to fight the mildew to a standstill. It’s actually under 55% most of the time, but humid summer days are killers.

Being the sort of bear who owns a Kill-A-Watt meter, I jotted down dates, runtime hours, and kWh when I filled each 5-gallon bucket. Eventually, we acquired a cheap scale that found its way under the buckets to weigh the outgoing water.

My data collection foundered on errors of omission, power failures, and general forgetfulness, but, nonetheless, a few interesting numbers emerged.

Outside weather:

  • Dry weather = 0.14 kWh/elapsed hour
  • Wet weather = 0.37 kWh/elapsed hour

It draws about 485 W, so the duty cycle works out to

  • 0.14 kWh/hour -> 140 W -> 29%
  • 0.37 kWh/elapsed hour -> 370 W -> 76%

If I were more industrious, I’d grab a plot of daily humidity from the NWS and rub those numbers against it, but … maybe next year.

The thing requires somewhere between 2.0 and 3.5 kWh to extract each pound of water. It’s rated at 1.6 liter / kWh = 3.5 lb / kWh, undoubtedly under standard conditions, so the actual efficiency is in the right ballpark.

3 thoughts on “Dehumidifier Performance

  1. Hey Ed,

    Just wanted to say you have the most fascinating blog entries. I have taken to reading every one even if the title doesn’t seem all that interesting when it pops up in the RSS reader. You always surprise and you lead an interesting life. :)

    Keep on hacking and keep on telling us about it! I need someone to point to more geeky than myself when my wife gets on my case… ;)



    1. you lead an interesting life

      I think that’s the traditional Chinese curse, isn’t it? Of late, it’s certainly applied around here!

      more geeky than myself

      It’s an ugly job, but somebody’s gotta be the kind of guy you point out to your kids and say “If you [don’t] do x, you’ll wind up just like him!”

      Glad to be of service…

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