If you really want to know the real numbers, rather than theoretical book numbers, which are next to useless, you can buy clamp-on amp meters for really cheap now. Then you would need an extension cord, where you (carefully!!) split the wires, leaving both insulated, so that one could be clamped around. These amp meters only work if one of the wires are clamped. If you use an extension cord, you can use it for all sorts of things around the house to see what they use too.
I was really surprised at how cheap these amp meters have gotten to be. They are accurate, too. I took one over to a certifying lab and they wanted to test it for free on a lark cause they couldn't believe anything that cheap would be worth a damn. Not many years ago, they cost hundreds, now they are down to $20 or so from here:
Put a low value resistor in the neutral lead and measure the volt drop, if its an AC supply and the fan is an inductive load this won't be exactly accurate - but probably close enough.
With nothing much , other than clocks on in the house , take a reading on the billing consumption meter and then 10 minutes later. Then time for 10 minutes each of the 3 settings and consequential consumption readings
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
This is the next to useless number I mentioned in my post. It is the theoretical maximum amount based on the theoretical voltage. In the field, voltage can vary and so can the usage. I know it sounds nutty, but I've seen variations of more than 15% from the theory and that, to me, is unacceptable.
Don't assume. Buy it and test it like I did. The lab said +-3%. I consider that to be acceptable. If you don't like those numbers, then buy one for $300 and compare it to what you suggest the "book" numbers are.
Gee, if they are down to $20 that would be a good deal, too. Last I saw them, they were at about $35-40 and I thought was a bit too much for curiosity's sake.
It's going to continue to be a bit confusing... google lasko fan watts and you'll find several entries that include comsumption.... but most say 170 watts, one says 165 watts, and yet another 70 watts.
There must be a rating plate somewhere on the machine or motor, though... isn't it a legal requirement?
You still don't know what the power factor is with that route, a lot of cheap motors are closer to 0.5 than to unity, so the calculated wattage can be nearly double what the motor actually draws.
Thanks a lot, Bill. Is your Lasko a model 3723? That's the one I have (two of, actually).
Also, I went to the Kill-A-Watt web site. It looks like you can't measure any appliance running at 220 volts, correct?
I have a wall A/C unit in my apartment that plugs into a 220 outlet. I read somewhere that even a fairly small one of these units uses 3500 watts. I imagine that the 3500 is only when the A/C is running the compressor. So the average wattage would depend greatly on the outside temperature, I would think.
I have the UK version which is not even branded, but looking at it, it's obviously internally identical to the Kill-A-Watt. It's designed for 240V but works fine all the way down to 60V so I suspect the 120V model will work on 240V but have not opened one up to compare. At any rate the power supply is a simple capacitor and zener arrangement so it would be easy enough to modify with a lower value capacitor if the zener heats up too much on 240. If in doubt, it shouldn't be too hard to get the UK model and build some plug adapters as I did, back before it was widely available in the US.
I used mine to measure the draw of my 3 ton (36,000 BTU) central AC and found that the outdoor unit draws about 3500W with a power factor of 0.91. You're correct that current draw varies with head pressure which varies with outdoor ambient temperature. I doubt your window AC is bigger than 1 ton, so even with the indoor fan, I'd be shocked to see it drawing more than 2KW and really it's probably closer to 1200W.
Hey, I found the "electrical info plate" on the Lasko. It was stamped into the sheet metal on the bottom of the fan. After being stamped, the sheet metal was painted, which obscured the stamped info so completely that the only way I can see it only with a bright light held at an angle. As near as I can tell, it says "Model 3723 (last two digits very unclear, could be almost anything) Style EC437 (again very unclear) Type 1 E20739 Listed 154C (UL symbol)
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