For inductive loads like motors, I wouldn't trust those consumer-grade
"kill-o-watt" meters any further than I could throw them. They won't be
measuring the actual power being used the same way that your utility
power meter does.
For electric baseboard heaters, incandescent lights, toasters, electric
stoves, kettles, boilers, electric hot-water heaters - the kill-o-watt
meter will work ok.
For inductive loads like compressors (fridge, air conditioner, furnace
fan) and especially anything with a switching power supply like your
desktop computer, TV, CFL or any other fluorescent lights - forget it.
Thanks to all who answered. I forgot that the Kill-a-Watt meter, which
I have, did cumulative watt-hours and it also give the number of hours
that the data was collected. So, I put it on yesterday afternoon.
After 17 hours, it was about 2KWH. We pay 11 cents per KWH. I'll keep
you all posted on the final results.
Finally got all results.
Old fridge 3kwh per day, 11 amps defrost, 3.5 amp compressor, .59 pf, 250
90's fridge 1.4 kwh per day 3.6 amps defrost, 2 amp compressor, .8 pf.,200
Looks like the old one needs better insulation, but the defrost is sucking
power. I don't have any switch for door heater on the old one, and not sure
if it has a door heater. Even though I like the old fridge, maybe I should
watch craigs list. Got somewhat smaller fridge for my sister last fall.
$125 one year old, nice unit.
I should also look into rebate, and I don't want to pay for freon removal.
I, too got results of measuring the 38 year old freezer. Over 64 hours
of use, it averaged 2.72KWH per day. The room ambient has been pretty
much a constant 68-70 degrees during the measurement period. In the
summer I would probably be about 8 to 10 degrees warmer. At the
$0.11/KWH, that's $0.30/day or $109.10/year. BTW, my electricity charge
is probably going to go up in the next few months ... there is a case
presently under review. Anyway, even if I save $50/year, it would take
a whole lot of years to pay for a replacement. Interesting.
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