re: repair of attic vent fan SOLAR.KnowledgePublications.com

re: repair of attic vent fan
15 jun 2004
> -------------------------  
>|            |  /f        |    we might block the soffit and ridge vents 
>x|       ----| / a <--   |x    and close manual doors over gable vents
>x|      /f   |/  n       |x    and put one of grainger's 4tm66 fans near 
>|  <-- / a   |   |        |    the top of a duct to push attic air down to
>|     /  n   |   |        |    the house in wintertime, with another fan
>|---------|||-|||---------|    close to the attic floor to pull air up,
>|                         |    and 2 heavy plastic-film one-way dampers
>|       winter day        |    that close when the fans are off.
                              
with more distance and less short-circuiting between the house air
supply and return, and more attic ventilation in summer, and more
reliable motorized dampers (viewed in a fixed font)... 

m ------------------------  
x|                   f    |   
x|               <-- a    |    fan on.
x|                   n    | 
| xxx                |   m|    (m is a damper motor.)
|    |               |   |x
|  | |               | ^ |x 
|  | |               | | |x 
|-x|x-----------------x|x-|
|  |                   |  | 
|  v    winter day        |
                           
m ------------------------  
x \                  f    |   
x  \  <--        <-- a    |   fan off.
x __\                n    | 
| xxx                |   m|
|    |               |  / x
|    |               | /  x <--
|    |               |/__ x 
|-xxx-----------------xxx-|
|                         | 
|       winter night      |
                           
m ------------------------  
x \                  f    |   
x  \ <--         <-- a    |   fan on or off.
x __\                n    | 
| xxx                |   m|  
|    |               |  / x
|    |               | /  x <--
|    |               |/__ x 
|-xxx-----------------xxx-|
|                         | 
|                         |  
|       summer day        |  

m ------------------------  
x \                  f    |   
x  \ <--         <-- a    |   fan on or off.
x___\                n    |
| xxx                |   m|   with a 10 f temp diff and a 16' height diff, 
|    |               |   |x   16.6(2x2)sqrt(16x10) = 840 cfm might flow 
|    |               | ^ |x   out of the attic. 
|    |               | | |x  
|-xxx-----------------x|x-|
|                      |  |   active basement window dampers could warm 
|      summer night       |   the house with outdoor air flowing in through 
|                         |   the attic and indoor air flowing out through 
|                         |   basement windows on a warm dry day. 
|                         | 
|-------------------------|   
|____                 ____|   active dampers might have foamboard hinged
x         basement        x   on one edge and http://www.herbach.com's
x -->      windows    <-- x   $7.95 tm94mtr2651 120vac 13 oz-in reversible 
x                         x   72 rpm motor and 2 $3.25 tm94swh2570 limit
|                         |   switches. with a 1/4" shaft, the motor might 
|                         |   lift a 15 pound damper with a nylon string.

nick