I'm in California, USA. During the summer, the wall mounted air conditioner probably consumes around 80 to 90 percent of the electric power used in my apartment.
This AC unit has a 220 power plug that's plugged into an outlet right next to it.
Is there a Kill-a-Watt meter that does both 110 and 220 volts AC? I've heard of a higher than 110 volts model obtainable in Europe, but I would need one that works with the USA version of plug style, voltage, and AC frequency.
Thanks.
BTW, my DMM measures the "110 Volt" AC outlets at 123 to 125 volts.
I would hazard a guess that the inline European ones designed for 240v would also work on a 110v supply without too much trouble (probably less accurately and maybe needing empirical calibration).
But the other way around the US ones will be made down to a cheap and nasty price and probably cannot safely be used at 240v. The same seems to be true of many US wallwarts which are dedicated to 110v whereas in almost all other countries they are commonly for 100-240v 50-60Hz.
The clip on magnetically coupled devices like OWL are probably your best bet if the cabling will allow the sensor to be fitted. Accuracy +/-10W is poor compared to inline ones but for A/C should not matter.
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I presume smart meters are also available in the USA, but a quick web search didn't show anything obvious.
It is probably more informative to use this type to monitor the entire apartments usage - you can deduce the aircons consumption from how much the thing jumps by when the compressor kicks in. You might need a pair of magnetic sensors since ISTR US 240 is across antiphase 110v supply.
Probably not 'Kill-a-Watt' brandname, no (those are consumer-grade and made for the lowest price possible). The meter on your house does it, though, and lots of other power meters can do it, too.
Your AC 220V unit undoubtedly uses more current than a standard wall socket 220V Kill-a-Watt is meant for. On the used market, the house-power-meter gizmos go for $50 and up...
Mike's metrology question: What are you gonna do with the information when you get it?
You save money by turning up the thermostat or turning it off. You don't need any power measurements to do that.
The utility company has a meter on your dwelling. You can read the numbers and get gross answers. By timing how fast the wheel (real or simulated on an LCD) goes around, you can get short-term numbers. The scale factor is written on the meter face although cryptically.
Put the house in stable power drain. Time the wheel. Run the air conditioner full on. Time the wheel. Turn off the compressor, leave the fan on. Time the wheel. Turn the air conditioner off. Time the wheel. If the first reading isn't the same as the last one, something turned on/off that you didn't expect. Repeat the process till both numbers are the same.
One thing that surprised me is that the fan consumes an appreciable percentage of the total power...and it usually runs all the time on a window unit. You know the fan consumption from the measurements above times the time the unit is on. Pay attention to how often the compressor runs to get the other part of the consumption.
Now what? You can either turn it off or turn up the thermostat. And you already knew that.
In my case, the 20" box fan that I use to vent the house in the evenings takes about 15% of the energy used to run the central air. So, if the air conditioner runs less than 15% of the time at night, it's cheaper to leave it on than to run the box fan all night. That's critically dependent on your insulation. Moving air is expensive, even if you don't try to modify its temperature.
If you have an electric water heater, that can consume significant energy. Typically, there's nowhere to hook up a kill-a-watt to that. But timing the meter wheel still works. And you don't have to worry about power factor. The wheel tells you EXACTLY what the utility is billing you for.
Bottom line is that you already have the means to make the measurement for free.
Having a cool toy that continuously reads consumption is fun until the new-car-smell wears off, but the payback period for the purchase can be LONG. I paid $2 for my KAW at a garage sale. Don't expect to save an extra $2 because I have it. I already had a stopwatch.
Kill-A-Watts monitor the neutral current (keeps the innards at a low voltage), so are useless, as is, for standard US 240V split-phase. A friend hacked one to monitor the hot current and it worked just fine on a 240V circuit. Safe? Well, it was hacked. ;-)
" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote in news: snipped-for-privacy@4ax.com:
I just used mine on a 300W boost PFC and according to the kill a watt my boost converter is makeing power. For a measured 130W out the Kill a watt says my boost is only drawing 115W @ 0.97 PF.
I have seen it get closer on other SMPS's but its off here!
But he is basically correct. The big cost is incurred maintaining a huge temperature differential.
Raising the internal temperature to be closer to the external one is actually more comfortable too. I have lost count of the number of US premises where in summer conference rooms are kept so cold that you need to put on a sweater or jacket to survive. In winter the situation is reversed with everywhere kept soporiphically warm and stuffy.
Which they struggle to read correctly. Mine is prehistoric with alternate dials with opposite handedness and in a most awkward corner.
However, if you can clip a magnetic sensor onto the mains inlets then you can measure total power delivered (and most of it will be going to the aircon and/or and electric cooker or space heaters).
A realtime display in your living space makes you aware when something has been left on. The one we fitted to our village hall has saved a fortune by preventing the main hot water immersion heater being left on when people leave.
I thought it is 115V in America today.... Old appliances in europe had 220-240V (written on a backside-badge) input. The former 220V standard has been raised to 230V today.
Bad designed circuitry, awaiting exactly 110 or 220V, might have a heat-problem.... that's all, but can destroy a device in long term though.
Or lowered to 230V for the UK and Eire, where it used to be 240V. For now, anything sold in the EU must work with 230V +/- 10% (207V-253V).
It's a problem for incandescent light bulbs, which need to run close to the filament's limit for maximum efficiency. A bulb designed for 240V will produce signficiantly less light at 220V, while a bulb designed for 220V will burn out rather quickly at 240V.
You're being WAY too sensitive. Just facts. No need to take it personally.
Interesting...there's gotta be a meter somewhere??? Talk to your landlord. The point is that you only need to measure stuff once. From then on, the meter just sits there doin' nothin'.
Yep, I learned that and no longer need to measure that.
Still way too sensitive.
This is the first time I've seen you mention this. Was all about the A/C.
BUT, reading the meter works for ANYTHING you use.
If you find you do have access to the meter. AND If you have an old palm pilot or handspring visor with PalmOS 3 or 4, I can send you a program that can monitor/graph the newer electric meters with the digital readout and led that pulses every watt-hour. Turns out that WalMart sells yummy deserts in a plastic container that's a press-fit over a utility meter and just the right size to hold a Palm. You can log yourself silly. Problem is that you have to add bigger batteries to get enough life to run 24 hours..
I just ran around the house with a watch and turned stuff on/off. Go retrieve the palm and correlate the graph with the times you turned stuff on/off. I can tell you exactly how much it costs me to take a shower. I couldn't have done that with a killawatt. And I only needed to measure it once. It's pretty linearly related to how long you run the hot water. Shorter showers cost less. And I already knew that. And I don't take shorter showers because I actually measured the number. YMMV.
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