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Old 04-05-2008, 10:49 AM   #40 (permalink)
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Join Date: Dec 2007
Location: San Jose
Posts: 319

Pablo - '07 Hyundai Santa Fe AWD
90 day: 23.62 mpg (US)
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Quote:
Originally Posted by mopo3 View Post
MBH = thousand BTUs per Hour?
Exactly

It does not include the water heater's capacity. It's just looking at the usage. Most gas water heaters consume around 40 MBH and their output is less so they wouldn't be able to sustain a 2.5 gallon shower. Electric waters typically have 3KW, 3.8KW or 4.5KW elements. Since for the vast majority of them only one element is on at a time, the recovery is only 10 - 15 MBH. We shower until we are clean or the water gets cold... unless you are my kids and then you shower until the water gets shut off from the basement by the BTU keeper.

BTUs make for hard numbers. A BTU is the energy needed to raise one pound of water 1 degree Fahrenheit. The pounds per gallon varies with temperature of course but not enough to factor here. They are accurate units but sinfully outdated. North American home energy metrics are like aviation in that they are slow to switch over to metric, even when you live in a metric country.

Thanks for the explanation of mols.
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