02-24-2009, 11:30 AM
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Deity
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Join Date: Jul 2004
Location: Saint Regis Falls, NY, USA.
Posts: 4,977
Thanks: 0
Thanked 102 Times in 102 Posts
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the fan is controlled by an air plenum switch. basically it's a coil that is in the air stream and expands and rotates closing a set of contacts. the contacts can be set for minimum temp and a max temp band.
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