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  #1  
Old 02-13-2006, 08:58 AM
markotah
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Default kWh / KW ????

I see on my bill I used 703KWH last month. My water heater has a 4500 watt (4.5KW) element in it. If I ran the unit continually for 1 hour how would I calculate the KWH?
Thanks,
Mark
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  #2  
Old 02-14-2006, 10:51 PM
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Default Re: kWh / KW ????

As its name implies, kilowatt hours is indeed kilowatts * hours.

4.5 kilowatts * 1 hour = 4.5 kWh
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Old 05-16-2007, 02:15 PM
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Default Re: kWh / KW ????

thx for helping with my energy econ homework
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Old 07-29-2007, 11:37 PM
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Talking Re: kWh / KW ????

Thanks for helping me with my homework too =D
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Old 10-11-2007, 11:48 AM
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Default Re: kWh / KW ????

thanks for doing my homework
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Old 11-28-2007, 10:30 AM
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Default Re: kWh / KW ????

that ******* is wrong! i failed my test because of him!!!
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Old 11-28-2007, 02:50 PM
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Default Re: kWh / KW ????

Quote:
Originally Posted by Unregistered
that ******* is wrong! i failed my test because of him!!!
no, Robert's answer is not wrong. kWh is KiloWatts Per 1 Hour. if a water heater had a 4.5 kW heating element, that ran for 1 hour (60 minutes, or 3600 seconds) --which is exactly what the question asked-- it would consume 4.5 kWh of power.
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  #8  
Old 12-04-2007, 07:13 PM
Pizza_Pi (Visitor)
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Default Re: kWh / KW ????

kilowatt-hour (kWh) is a unit of Power. 1 kilowatt-hour means that it will use (or transfer) one kilowatt every hour. One kilowatt is the power of one thousand joules (J) per second (s). the h in kWh basically signifies just the alternative time unit used. It is used because it often provides results that can be explained in whole numbers easily with out common household appliances.
If you really want to know what the conversion for kWh to kW...
1 kWh = 0.000277777...kW
1 kW = 3600 kWh
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Old 12-04-2007, 07:16 PM
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Default Re: kWh / KW ????

The conversion:
1 kWh = 0.00027777... kW
1 kW = 3600 kWh
1 kW = 1000 J / s

So, the answer would be 4.5 kW = 16200 kWh, or 16.2 mWh (megawatt-hours)
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  #10  
Old 12-04-2007, 07:25 PM
Pizza_Pi
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Default Re: kWh / KW ????

1 kW = 1 kW consistent for 1 hour, or 1 kWh
1 kW = 1000 J / s = 1 kJ / s
1 kWh = 1000 J / h = 3.6 kJ / h
kW (kilowatts), kWh (kilowatt-hours), J (Joules), s (seconds), h (hours), kJ (kilojoules), mJ (megajoules)
But if you ant to find how much power was consumed in an hour, then you multiply 1 kWh times 3600. You can look above to find conversions to Joules per second, and, including the units, you find that the two time units cancel out each other:
kWh / kW = (1000 J / h) / (1000 J / s)
= (3600000 J / s) / (1000 J / s)
= (3600000 J / s) * (s / 1000 J)
= 3600

Just some prefixes for units if you ever want to know.
(f) fempto = 0.000000000000001
(p) pico = 0.000000000001
(n) nano = 0.000000001
(micro symbol) micro = 0.000001
(m) milli = 0.001
(k) kilo = 1,000
(M) mega = 1,000,000
(G) giga = 1,000,000,000
(G) tera = 1,000,000,000,000
(P) peta = 1,000,000,000,000,000

For your information

If anything is wrong, tell me now and prove it. I always want to be right.

Oh, and Mark, the heater used 4.5 kWh, and it will consume 108 kWh daily if you leave it on 24/7.

Last edited by Pizza_Pi; 12-04-2007 at 08:05 PM.
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