Sticky Wicket
Dear Suzy,
Should I spring for a dehumidifier? My folks swear by theirs. I just can’t figure — between the outrageous amount of energy a dehumidifier consumes and the fact that in Austin I’d be changing pans about every hour — whether it’s really worth it. I know that running one will allow us to run the AC at a higher thermostat setting, but stiiilllll…
Your insights into this sticky matter would be appreciated.
Jeanine
Dear Jeanine,
I’d say if your parents swear by the dehumidifier, make ’em buy you one as a token of their beliefs. But for me, the idea is suspect. Not that I suspect parents in general for misinformation; I called my own dad, an electrical engineer, to help us with the numbers on this one.
First, I looked up dehumidifiers in the hefty 3578-page W.W. Grainger Catalog. The two models they offer range in price from $232 to $391. (Mind you, these are close to wholesale prices. List prices range from $348 to $587.) They remove 15 to 50 pints of water in 24 hours when the humidity is 60% and the temperature is 80 degrees. The mid-range model uses 6 amps at 115 volts.
Then I called my dad, the man with the formula. If we multiply the amps times the volts (6 x 115), we’ll get the number of watts consumed in an hour: 690 watts. This is translated into kilowatts by dividing by one thousand: .69 kilowatts. If you run it 24 hours a day, you’d use 16.59 kilowatts per day. Let’s assume you pay the City of Austin’s residential rate for more than 500 kilowatt hours, about 8 cents. So .08 x 16.59 equals $1.32 per day or $39.81 per month.
How much higher did you plan to set your thermostat? A hundred-and-one?
I’m not sure the savings — in dollars or energy — are there. My dad — the smartest man on earth who turns 70 next week — says that your air conditioner is a much more efficient dehumidifier than one of these Grainger units, but only if it’s properly sized. If your unit is too big and doesn’t have to run long enough to lower the temperature, it won’t have time to circulate all the wet air in your house.
He also says that circulating the air at a high enough velocity to “scrub the envelope” of heat that surrounds you will also make the humidity seem to disappear. Grainger sells some nice fans, the kind that will last more than one season, for $30 to $50. They average around 2 amps at 115 volts. Wanna do the math? Two times 115 equals 230 watts. Divide by 1000 to get .23 kilowatts. Multiple .23 times 24 hours for 5.52 kilowatt hours per day. Multiply this by 8 cents per kilowatt hour and you’ll be spending around 44 cents per day or $13.24 per month. (I think we should consider that you probably won’t have to run the fan when you and your heat envelope aren’t there, unlike the humidifier which probably has to chug along all day to suck up the sog.)
Or you could move back in with your parents for a few weeks and see if they don’t suddenly offer to pay your utility bills if you’ll leave.
I want your questions to move in with me at: Suzebe@aol.com Or snail mail ’em to: The Austin Chronicle, PO Box 49066, Austin, TX 78765.
This article appears in July 4 • 1997 and July 4 • 1997 (Cover).