# Appropriate Temperature Differential for Attic Fan

If an attic fan is properly sized, and properly installed, what should be the temperature differential between the outside air temperature and the attic temperature, while the fan is running?
Assume there is plentiful air intake in the attic from outside air.
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W

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After your last post what makes you think.......?
http://tinyurl.com/o27sfo
co
"I have been called bad before. Many have said I do things that are not correct to do. I don't believe in talk such as this. I am nice man, with happy feelings. All of the time. First, a joke. What do you get when you cross an owl with a bungee cord? [pause] My ass. Nyah, haha, haha, haha, ENOUGH!"
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Attic temperature depends on the amount of solar radiation, construction details and the rate of ventilation. Calculations indicate that on a July day in Texas, a ventilation rate of one air change per minute for a typical attic using 95-degree F air will lower the peak attic temperature to about 101 degrees F. Providing half air change per minute will lower the temperature to about 106 degrees F. Thus, the first half change per minute is most effective and a doubling of this rate only achieves about 5 degrees F additional cooling. Studies indicate that further increases in ventilation are not effective in significantly reducing attic temperatures.
Calculate the required summer ventilation rate by determining the volume of attic space and dividing by 2. This will be the cfm (cubic feet per minute) of ventilation air needed. The volume is determined approximately for a rectangular house by multiplying the height from the ceiling to the peak/ridge (H) times the width of the house (W) times the length (L) and dividing by 2 -- ( H x W x L / 2 ). For a gable roof, this will be reasonably accurate. For a hip roof house, the volume will be overestimated but adequate.
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W

"W" < snipped-for-privacy@spamarrest.com> wrote in message
news:MsydnX0uibsmEoDXnZ2dnUVZ snipped-for-privacy@giganews.com...
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Could you convert that to BTU's so that we can understand. Thanks.
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Why don't you just stick your dick in the fan?
A warm day at home will seem pleasant by comparison.
--
Build a fire for a man, he\'s warm for a day.
*Set* a man on fire, he\'s warm for the rest of his life.
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W wrote:

Why bother to have an attic at all? If the damned thing needs a fan to cool that wasted space it is just a ridiculous expenditure of energy.

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Depends what time of day. How much humidity, and how much sunshine.
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Christopher A. Young
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