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Roofing/attic fans with automatic thermostat and humidistat


home owner wrote at 2011-06-27 13:11:38
in the summer your thermostat should be set to 90/95% and in the winter your humidistat should be set to 40%,these settings work for me without any problems.GOOD LUCK

Schaumburger wrote at 2014-11-15 14:49:28
I'm in Schaumburg, a Chcago northwest suburb.  My attic humidistat is set at 75%.  From yesterday evening to now, 8:30 Nov 15, my fan has been running nonstop.  Outside humidity shows about 80% with temp at 25 degrees.  I'm tempted to go set the humidistat to 85%, but the fan will just keep sucking in the outside humidity.  I burned one fan out in Feb this year, and had the attic rebaffled (between EVERY joist) for more ventilation, and reinsulated.  There dont seem to be any pat answers to this issue.

Schaumburger wrote at 2014-11-16 05:40:12
You rule of thumb is more for in the house, NOT the attic.  Overnight Nov 15, 2014, my humidistat/thermometer outside measured 23 degrees and about 80%.  My humidistat is set to about 75%, and the fan ran all night and part of this morning, when the temps rose and the humidity dropped.  Your attic should mirror what is outside for humidity, according to the AdvantaCean folks who remediated my attic.  Summers the attic fan will more likey kick in due to the thermostat controlling the fan for heat, again pulling outside air in thru the attic soffits to cool it down.  


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Todd E. Miller


I am available to answer any questions pertaining to residential (or other sloped) metal roofing. I have knowledge of most available products but I like to approach projects from a "needs" basis and analyze them individually. Additionally, I can answer most questions about building ventilation.


I have worked for a manufacturer of residential metal roofing since 1980. I currently serve as President and have been involved with a wide variety of projects of all types across the world.

I am a board member for Metal Construction Association, Metal Roofing Alliance, the local United Way, our church, and our son's school.

Over the years, I have had articles appear in several trade journals including RSI, Remodeling, and Qualified Remodeler.

I have a B.A. in Communications and have also completed three years of training with the E-Myth Academy.

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