just like a pbr: cool and cheap

April 18, 2008 9:26 PM

a couple of air conditioner energy-efficiency questions.

i have a couple of fairly new window units in my apartment. both have a "fan only" function that (duh) runs the fans without using the compressor.

1. i assume the "fan only" function draws less power than running the compressor, right? anyone know by how much?

2. does my a/c's fan draw more power than a regular ol' box fan? if so, how much more?

posted by thinkingwoman to home & garden (6 comments total)

It should draw more power per unit circulation than a box fan, because the air channel is more encumbered, so it should take more work to push the air through.
posted by Class Goat at 9:29 PM on April 18

1) Yes. The compressor is the expensive part of the equation, requiring a much beefier motor than the fan. Beefier = more voltage, more amperage. More wattage.

2) Way, way more power.
posted by Netzapper at 9:55 PM on April 18

The fan only mode draws much less power than the air conditioner. I would expect about 80% less. It will be less efficient than a box fan for the same amount of airflow, but just running a fan is probably not enough energy to make a noticeable difference in usage.
posted by cameldrv at 9:57 PM on April 18

If they're fairly new, do you still have the owner's manuals? Most owner's manuals will have a section on power consumption. But generally, yes, as the others have said, the fan-only setting will draw more power than a regular box fan, but considerably less power than the air-conditioner setting.
posted by amyms at 10:57 PM on April 18 [1 favorite]

Small aircon: 1kW. Big aircon: 3kW. 15" pedestal fan: 65W. Aircon fan: 100-150W.
posted by polyglot at 12:48 AM on April 19

Just checked out the specs on my small 5000 btu windows unit. The whole unit is 530W, the compressor alone draws 450. So, a lot.

But look at the efficiency of the whole system- your box fan runs constantly, the compressor runs occasionally and actually removes heat from the room, as opposed to just blowing it around.
posted by gjc at 10:10 AM on April 19