[radtek]

I bought a 1192sq house built in 1974 Dec 2007. It is aligned East to West so gets full sun all day long- without much tree-shade!

The previous owners used it as a rent-house and neglected it. Not a real problem as I'm fairly handy.

But, to the question(s):

I have two Gable vents and two wind-turbines. The gable vents measure 37"x30" and the wind turbines are 14" across.

Gable vents= 2220"sq total
Turbines= 307sq" total

It gets really hot up there during the day. Last night I ventured up in the attic with my infrared about 2am. A nice comfortable 75F while the outside was a very nice 65F! I understand this is about right...? There appeared to be a nice flow of air at that time.

Additionally there aren't any soffit vents at all. I bought a case of vents two weeks ago and have been scheming on putting them in. Is it overkill and unnecessary to install soffit vents?

I've got other plans concerning insulation but I'll leave that for another thread.

rad

 

[Just Bill]

You certainly have ample space to get hot air out, but getting cooler air is limited to the east side in the afternoon and the west side in the morning(when it is not needed). Those whirely birds(they are whirley birds???), give a good vent to hot air at the top of the attic. Soffit vents would allow cooler northern air in all the time. Adding them can't hurt, but I stop short of suggesting a ridge vent for your area(in addition to what you have).

 

[Gary in WA]

I enjoyed this starting on 604......... http://books.google.com/books?id=Z8...m8D7AQ&sa=X&oi=book_result&ct=result&resnum=3 This talks about wind-washing also: http://www.blocktheheat.com/ventproblems.htm Be safe, G

 

[radtek]

As the volume of insulation goes up in the attic how does this affect the venting? It seems reasonable that this reduces the volume of air available in the space and correspondingly less hot air to be vented out.

 

[radtek]

I've installed about 20 vents on the front (South-facing) of the house. I went and re-read the .pdf http://books.google.com/books?id=Z8...m8D7AQ&sa=X&oi=book_result&ct=result&resnum=3

Of course it is incomplete! Anyway, It states "there are two ways to install louvered vents and one is wrong" but doesn't clarify itself. I placed the louvers facing outward to catch the air flow. I also placed them closer to the leading edge of the roof instead of the wall. I'm a little worried about rain when it is gusty in this arrangement. Not that we get all that much, but the drought will break eventually and we are well known for the violent storms that sweep through on occasion. I plan to install rain-gutters as well so that might mitigate some water penetration when windy.

In the pic the first two vents have the louvers facing inwards- my goof!

I need to do the North facing side. And I want to do it right. Ideas guys? Please, before I do anymore "elective surgery" on my house!

 

[rwa]

hope there's some insect screen under all those vents

 

[Gary in WA]

I would think the vents should be open to the house side, not to let snow or rain in from gusty wind. I researched this extensively, and found nothing. I figured as the wind hits the roof eave, it is pulled upwards from the wind traveling up the roof creating a high pressure, compressed wind. Venturi effect. The outer edges of this wind travels past the vents and pushes the moisture into it. There is also the low pressure in the attic, sucking moisture in the soffit vents, as the wind pulls the air out the ridge vents. That is why it is so important to have baffles on the ridge vents. But in your case the turbine vents. I may be wrong, it's happened before......
Be safe, G

 

[radtek]

Thanks GBAR- after I read that .pdf I was disheartened with the whole process. However, I will state for the record that that there has been an immediate and noticeable effect after I put those vents in on the South-facing part of the house. I've dropped my electric usage by over a dollar a day or 11Kwh! I would say that is significant.

I can say this with confidence due to my Blueline Powercost monitor where I track my usage to the penny.

Also. I suspect adding more vents to the Northside won't reduce my attic temps much further but it should eliminate stagnant areas in the attic.

Not an expert on how air behaves. But I'm visualizing what happens when movement is perpendicular to the wall. I think your low-pressure concept sucking the air into the attic may be valid. Much like an airplane wing. In a totally dry climate it probably wouldn't matter what direction the louvers face. I may reverse those louvers since we do get rain LOL.

BTW- these vents come with insect screening.

I'll do more research. sigh.