ISP Information:
The original parallel AGP standard that operates on a 32-bit bus at 66MHz speed for a maximum data transfer rate of 256MB/second.
ISP Glossary:
AGP 1x - On Tue, 30 Mar 2004 00:04:05 GMT, "Phil Sherrod" wrote:I recently installed an electric water heater to service a guest bedroomlocated far from the central water heater. Since water will be drawn from thisheater only when guests are visiting, I plan to leave it turned off to savepower.But before shutting it down, I decided to take some measurements and calculatehow much it costs to run an idle water heater.The water heater is an electric GE Smartwater 40 gallon, �lowboy� (squat) unit. The plate on the unit says it draws 4500 watts, but my measurements show thatit actually draws about 4320 watts (18 amps at 240 volts). The EPA estimatedannual cost of operation is $401.I used a Supco model DLAC recording clamp-on ammeter to record power (amperage)over a 3 day interval. During the same period, I used a Supco model DLTrecording thermometer to record the ambient air temperature in the crawl spacewhere the water heater is located.Here is a summary of my measurements:Monitored interval: 3 daysPower draw when heating element is on: 4320 watts (18 amps at 240 volts)Duty cycle when heater is running: 0.0161 (1.61%)Average power used (heating watts times duty cycle): 69.55 wattsTemperature of hot water delivered: 114 degrees F.Average temperature in crawl space during measurement period: 61 degrees F.Temperature rise for water: 53 degrees F (114 - 61)When the heater is on, it draws 4320 watts. However, the duty cycle(proportion of time heating) is only 0.0161 (1.61%), so the average power drawnis 4320*0.0161=69.55 watts. (On average, the heating element is on 23minutes/day.)An average power usage of 69.55 watts over 24 hours works out to 1.669 KWH(kilo-watt hours) per day.The EPA average national power rate is 8 cents per KWH. So, using the EPApower rate, the cost of keeping the idle water heater hot is 13.35 cents/day or$4.00/month or $48.73/year.Here in Tennessee, we enjoy relatively cheap TVA power which costs 5.6cents/KWH. Using that rate, the energy cost is 9.35 cents/day, $2.80/month or$34.13/year.The EPA estimated annual cost of operation is $401 (assuming 8 cents/KWH). Sothe idle heat-loss cost of $48.73/year is about 12% of the total cost.If you adapt these figures for another location, remember that the cost isdirectly proportional to the temperature difference between the hot water andthe surrounding room temperature, and you must adjust for your KWH power cost.Phil Sherrod(phil.sherrod 'at' sandh.com)Index: power, energy, cost, water heater, waterheater, KWH, energy use, cost ofhot water, hot water cost, efficiency, power rate, electric water heater,Phil, get a life, friend! Hell, if you ain't going to be using it anymore than that, why didn't you just tap off the house water heater?That's like buying a big nice boat and going fishing about once ayear.
|
