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Thread ID: 83338	2007-09-28 01:41:00	How to measure appliance power usage	MeOldMate (12871)	PC World Chat

Post ID	Timestamp	Content	User
595894	2007-09-29 10:15:00	what a new fridge will cost to runMy old mate Dan gives some insight into this question, here (www.dansdata.com).	Greg (193)
595895	2007-09-29 15:03:00	My old mate Dan gives some insight into this question, here (www.dansdata.com). Good article, Greg...but I hope I can phrase this question correctly to make it easy to understand. (Calling all electrical phDs!) IF you are using this sort of meter on a Green Appliance, isn't the return reading(s) going to be 'way off? If a green motor for instance is actually saving current consumption via clipping the peaks off the upper and nadir sine wave, won't the results on the meter's readings be way off? I think I saw some incriminating evidence of this possibility in the test he made to the glowing lamp at 0 (zero) watts. That would indicate to me that the meter cannot compensate for closer to 100% efficiency devices and would therefor skew the numbers into illogical values. Quoted here: "....Power factor ought to be 1 for simple resistive loads (heaters, toasters, incandescent light bulbs), but things like old PC power supplies (the kind with a red "115/230V" switch on the back) or lightly loaded motors ought to have power factors considerably below 1. I've tried the meter with a few old PSUs (two sitting there naked, one powering a PC), and with a desk fan, and it still always says "100". I even tried removing the impeller from the desk fan, so the motor was turning with no load at all; the wattage figure dropped a bit, but the power factor was still allegedly 100. If you don't correct for power factor, then something like an old PC PSU with a PF of about 0.7 will appear to draw 1.4 (one divided by 0.7) times as much power as it really does. But when I plugged an eleven watt compact fluorescent lamp into the meter, it read exactly 11 watts. If it wasn't correcting for power factor, it ought to have reported a higher number. So maybe it's doing it, and just not reporting the power factor figure properly. (As a sanity test, I also plugged a glowing-flowers bulb into the meter, and got a reading of zero watts, which is also about right. Unlike some night lights, glow bulbs draw very little power. At the other end of the scale, the meter also reported 502 watts sliding to 497 watts when I plugged a "500 watt" floodlight into it. That's an incandescent bulb with a power factor of 1, though, so it's not hard to measure it accurately.)" Maybe this is what he saw too...efficiency messes with the readings and the results. What I believe is happening is that more efficient devices will not be reported correctly and people might perceive that the expense of upgrading is not worth the cost in the foreseeable future..or at least a long time, when i reality it's apples/oranges here. The whole must be equal to the sum of the parts.	SurferJoe46 (51)
595896	2007-09-29 20:33:00	Too complicated for me. I didn't even realise that electrons rode little waves. I thought they all lined up behind each other and took it in turns to rub the light bulb fillaments (I'm sure I saw a diagram of that somewhere). On second thought I don't think I'll buy the meter - it'll be awkward to arrange co-buyers and visitation rights. And I can't get one till November anyway. One thing that can't be gainsaid is the actual KW usage. I'll do the test, then take the Aussie figures to compare to, since they are higher, so I'll get a conservative answer of savings (and the Oz figures are probably correct since they come from a government - i.e. someone who has the ability to fine companies that lie) Since there are hundreds, nay thousands, of you out there hanging on my every word, I'll be sure to let you know the answer.	MeOldMate (12871)
595897	2007-10-09 02:11:00	Update on this: I've decided to stick with the old fridge. My total power consumption has been historically about $1,000 per annum, and according to my investigations refrigeration is about 10% of that. Even though my very old fridge will be less efficient than the average, it's also smaller than the average, so we'll go with the 10% figure. That means $100. If I would get a 30% annual power cost saving from a new fridge, that means I save thirty bucks. The price of a new fridge would be $700 to $900 for a similar size replacement. So, on power usage alone, taking the lower figure, it would take 23 years to recoup my investment in savings. Pretty rough figures, and open to dispute, but indicative I think that it's not worth worrying about. There are bigger savings to be made elsewhere. Besides, if I delay a couple of years, how much efficiency improvements might come through in that time? Who knows. But I bought today I'd be locked in for 20 years to today's standard. Plus, last argument: How much energy does it take to make and transport a fridge? Quite a lot I would imagine - so my postponement delays the manufacture of another unit and thereby offsets (cancels out?) my extra energy usage with the old one.	MeOldMate (12871)
595898	2007-10-09 15:32:00	Love it! Do you have a set of bagpipes and a kilt at home? You've done your homework...<applause> and I really enjoyed the logic.....VERY good on ya! Hoot, mon!	SurferJoe46 (51)
595899	2007-10-13 07:40:00	Update on this: I've decided to stick with the old fridge. My total power consumption has been historically about $1,000 per annum, and according to my investigations refrigeration is about 10% of that. Even though my very old fridge will be less efficient than the average, it's also smaller than the average, so we'll go with the 10% figure. That means $100. If I would get a 30% annual power cost saving from a new fridge, that means I save thirty bucks. The price of a new fridge would be $700 to $900 for a similar size replacement. So, on power usage alone, taking the lower figure, it would take 23 years to recoup my investment in savings. Pretty rough figures, and open to dispute, but indicative I think that it's not worth worrying about. There are bigger savings to be made elsewhere. Besides, if I delay a couple of years, how much efficiency improvements might come through in that time? Who knows. But I bought today I'd be locked in for 20 years to today's standard. Plus, last argument: How much energy does it take to make and transport a fridge? Quite a lot I would imagine - so my postponement delays the manufacture of another unit and thereby offsets (cancels out?) my extra energy usage with the old one. Well thought out, If only the government understood this....	porkster (6331)
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