Who was that looking for DC attic fan?

[GeekBoy]

This week's Home Depot circular has an a solar powered attic fan for $168.
Comes with 10 watt solar panel and available for either gable (item
#607688) or roof mount (item # 607690).


GB

 

[tom]

This week's Home Depot circular has an a solar powered attic fan for $168.
Comes with 10 watt solar panel and available for either gable (item
#607688) or roof mount (item # 607690).

for anyone considering Attic Fans, some reading material on the pro and con

http://www.advancedenergy.org/buildings/knowledge_library/ventilation/attic_ventilation.html

http://www.askthebuilder.com/236_Powered_Attic_Fans_-_Attic_Insulation_Facts.shtml

I (like so many) have been running dual thermostatic attic fans (bought from Home
Depot and Lowes) for 12 years, until I discovered that they indeed are worthless and
just used more electricity

 

[GeekBoy]

for anyone considering Attic Fans, some reading material on the pro and
con

http://www.advancedenergy.org/buildings/knowledge_library/ventilation/attic_ventilation.html

http://www.askthebuilder.com/236_Powered_Attic_Fans_-_Attic_Insulation_Facts.shtml

I (like so many) have been running dual thermostatic attic fans (bought
from Home Depot and Lowes) for 12 years, until I discovered that they
indeed are worthless and just used more electricity

Umm,,,,I guess you did not read the post. I did write they are SOLAR POWERED

 

[JoeSP]

This week's Home Depot circular has an a solar powered attic fan for $168.
Comes with 10 watt solar panel and available for either gable (item
#607688) or roof mount (item # 607690).

When I do the math, a 10 watt panel will provide enough energy to do
precious little air movement. I would probably go with a whirlybird vent,
backed up by a small duct-mounted AC fan, controlled by a two-stage
thermostat. The first stage would open an electric damper in the duct,
allowing the whirlybird fan to suck out the air. Then if the whirlybird fan
on the roof isn't doing enough, or if there's no wind, the fan in the duct
would kick in at the second stage of the thermostat. This way, you would get
adequate and controlled airflow at minimal cost, utilizing the wind whenever
possible.

Solar energy is free, but expensive, and rarely worth the investment when
grid power is available. Wind power is both cheap and free, but it's the
least reliable source. I think the best choice is wind-driven ventilation
with a grid power backup.

 

[mika]

Umm,,,,I guess you did not read the post. I did write they are SOLAR
POWERED

Umm... I guess you did not read the links... it does not matter (read the
links and you will find out why)

 

[GeekBoy]

When I do the math, a 10 watt panel will provide enough energy to do
precious little air movement. I would probably go with a whirlybird vent,
backed up by a small duct-mounted AC fan, controlled by a two-stage
thermostat. The first stage would open an electric damper in the duct,
allowing the whirlybird fan to suck out the air. Then if the whirlybird
fan on the roof isn't doing enough, or if there's no wind, the fan in the
duct would kick in at the second stage of the thermostat. This way, you
would get adequate and controlled airflow at minimal cost, utilizing the
wind whenever possible.

Solar energy is free, but expensive, and rarely worth the investment when
grid power is available. Wind power is both cheap and free, but it's the
least reliable source. I think the best choice is wind-driven ventilation
with a grid power backup.

The best thing I have seen is when a neighbor replaced his roof. He
installed a small vent that ran the entire length of the very top arch of
the roof. He also installed better vents at the bottom ridge. Since heat
rises, I see this as causing a natural draft to bring in cool air from the
outside.

 

[GeekBoy]

Umm... I guess you did not read the links... it does not matter (read the
links and you will find out why)

No need to . He said it was wasting electricity.
Can't waste what will not end for billions of years.

 

[tom]

No need to . He said it was wasting electricity.
Can't waste what will not end for billions of years.

actually, read the links and you will find why you are running A/C even harder (=more
electricity)

this has nothing to do with solar

 

[JoeSP]

The best thing I have seen is when a neighbor replaced his roof. He
installed a small vent that ran the entire length of the very top arch of
the roof. He also installed better vents at the bottom ridge. Since heat
rises, I see this as causing a natural draft to bring in cool air from the
outside.

Seems to me, most attics are already vented in such a way. Passive
ventilation from natural convection will still contain a fair amount of hot
air in the attic at any given time. Powered ventilation will reduce the
temperature in the enclosure in proportion to the volume of air movement.
That's why computer cases have fans and not just vent holes.

The trick is to close it when the weather is cold. It's good to retain heat
in this era of escalating energy costs. Some people I know draw heated air
down from the attic in the winter to feed through the furnace and save a
little on heating costs.

 

[GeekBoy]

actually, read the links and you will find why you are running A/C even
harder (=more electricity)

No matter what, most heat entering the home enters from the ceiling that is
being stored in the attic.

 

[surfnturf]

Joe,
Good attic ventilation is even more important in cold weather. Moisture from
condensation must be allowed to escape, or the area will become a breeding
ground for mould and fungus. Agree heartily with the rest of your post.
Cheers,
surfnturf

 

[GeekBoy]

This suction thing is a bunch of crap with a properly sealed modern home.

I agree since air will act live electicity and seed the path of least
resistance.
Those who believe in it apparantly cannot think on their own and hold every
article on the net as absolute truth.

 

[digitalmaster]

This week's Home Depot circular has an a solar powered attic fan for $168.
Comes with 10 watt solar panel and available for either gable (item
#607688) or roof mount (item # 607690).


GB

have you thought of a solar chimney?
Solar Chimneys: Where prevailing breezes are not dependable enough to rely
on wind-induced ventilation and where keeping indoor temperature
sufficiently above outdoor temperature to drive buoyant flow would be
unacceptably warm, a solar chimney may be an effective solution. The chimney
is isolated from the occupied space and can be heated as much as possible by
the sun or other means. Air is simply exhausted out the top of the chimney
creating a suction at the bottom which is used to extract stale air.


http://131.251.21.249/local/natvent/NaturalVentilationInBuildings.htm

 

[digitalmaster]

Roofs are solar chimneys. Put your vent on the peak where they are most
effective.

thats true but an additional solar chimney may be a replacement option
instead of the powered atic fan this person was looking for.

 

[Robert Megee]

This week's Home Depot circular has an a solar powered attic fan for $168.

Comes with 10 watt solar panel and available for either gable (item
#607688) or roof mount (item # 607690).

That may have been me. I already have a 45 watt solar panel and was
looking for just the fan. Most places I looked wanted to sell the
entire system not just the fan. I did try a dc fan that Home Depot
sold. The first one ran for all of 30 seconds before it died. It's
replacement was so damaged that it wouldn't work at all. At least
they gave me my money back. They were quite inexpensive and I know
why now.
I did find a fan. A 20 watt fan. I just hooked it up late yesterday.
I don't have any temp measurements yet but the difference in my
attic was very noticable. And that was at 6pm a bit past the peak
output. As for its affect on the cooling of my house, I suppose the
insulation between my living space and the attic should slow down
heat transfer but it's still there. And it's not even really hot here
in Texas yet.

Robert