Solar powered attic fan

[dad911]

Do you have enough attic ventilation as it is now?
For $3-400 you could add considerable ventilation, and not use any power. Hot air rises. Add ridge vent, or mushroom vents near the peak, to let the hot air out, and more soffit vent ventilation at the eaves to let cool air in.

You still need to add ventilation if you add a powered fan. Have to draw in fresh air to replace the air drawn out by that 1200 cfm fan, or you will not really be getting rated cfm of airflow.

[turbo6bar]

Originally Posted by dad911

Do you have enough attic ventilation as it is now?
For $3-400 you could add considerable ventilation, and not use any power. Hot air rises. Add ridge vent, or mushroom vents near the peak, to let the hot air out, and more soffit vent ventilation at the eaves to let cool air in.

The metric I've seen is 1 square inch ventilation per cubic foot of attic space. By that measure, I have 1/3 the number of soffit vents needed. I'm mixed on ridge vents because it will hurt in winter, when valuable heat is allowed to escape. Am I totally off base here? Even then, retrofitting ridge vent would not be a trivial task. The pitch is really steep. However, if the choice comes down to ridge vent vs roof vent, I'll take ridge vent.

You still need to add ventilation if you add a powered fan. Have to draw in fresh air to replace the air drawn out by that 1200 cfm fan, or you will not really be getting rated cfm of airflow.

Understood. The other worry is too few soffit vents would create negative pressure that pulls conditioned air into the attic.

I saw one energy conservation company stating their 20 watt solar fan moved 1275 cfm and kept a 1600 SF attic slightly over ambient temp. I find that hard to believe, but the company did not sell fans, so what reason do they have to lie.

Gonna do some rigging and report back with results.
jurgen

[slodave]

No info on the fan off hand. I will see it has a label later tonight, when I stop by my parents.

[dad911]

Originally Posted by turbo6bar

..... I'm mixed on ridge vents because it will hurt in winter, when valuable heat is allowed to escape. Am I totally off base here? .....

not enough ventilation causes other issues in winter. Ice Dams, Moisture,......
here is a pretty good explanation: http://www.dspinspections.com/atticventing.htm

[porsche4life]

http://www.thisoldhouse.com/toh/video/0,,20047003,00.html?bcpid=987453594&bclid=1025282652&bctid=1023793680