How effective are whirlybirds compared to half-round vents in venting an attic? I have a 1200 sq. ft, single story home that just had a whole house fan installed and I’m concerned that the air is circulating in the attic rather than being expelled outside. I’m hesitant about installing an attic fan because I have enough noise w/the house fan. Any suggestions/comments or anything to look out for if I decide to install whirlybirds or even a power vent? Thank you.
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Replies
Why not ridge vents?
I'm tempted to use a ridge vent but before I spend my hard earned cash I want to make sure they actually work. I have to admit I don't know much about them, however. Any good web pages out there?
I can't refer you to them, but mabe Building Science website.
I suppose that you're talking about round louvered wind turbines. Well they're are somewhat dependent on windspeed for their effectiveness.
I installed one on my garage roof a few years ago. It's made a big difference in the temperature of that space, much cooler. They move a lot of air when the wind's blowing and a fair amount, even when they're just turning slowly.
I'd say that putting a couple of them, one on either side of the roof's peak directly above the whole house fan, would be an effective way to clear the hot air out of the attic space.
On the other hand, I've been in one house with a whole house fan that was ducted out the gable end wall. That's the superior way to deal with it. Your attic and it's insulation won't be subject to rapid change in humidity or the dirt concent in the air being moved out of your home.
If the air entering the house isn't filtered, it'll be carrying small amounts of dirt which will eventually weigh down the attic insulation, compacting it and causing it to become ineffective.
Besides committing the crime of uglyness?
With venting, simple is better. Vents designed with moving parts will break and need servicing - I'll bet if you look around you'll see alot of still whilly's on a windy day.
Attic fans will add alot of air pressure to the attic, so much that it can actually blow back down through penetrations like light sockets and outlets. The half round vents, especially one right above the fan, can really work as a simple vent for that fan. If you have a dominent wind direction, you can set up a pair of vents to fill your attic with cool air on one side and expell hot air out the other.
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
Have to differ with you about turbines seizing up. They run on ball bearings and have a very long life span, in this neighborhood anyway. Thirty years and more without any complaints or replacements.
The only one I ever saw with problems was installed out of level. It belonged to my next door neighbor so I adjusted it for him.
Edited 5/19/2008 11:04 am by Hudson Valley Carpenter
Yesterday I was walking to my car after a kids birthday party... nice quiet neighborhood... except for the constant "SCREEEEEEEEEESCREEEEEEEESCREEEEEEE" coming from one house with a bad whirly.
The factory look is great for lofts and places that actually were factories. A tall round chimeny with a light at the top would be equally ugly.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
except for the constant "SCREEEEEEEEEESCREEEEEEEESCREEEEEEE" coming from one house with a bad whirly.
Could you tell if it was out of level? It takes some patience to adjust them to level in both axis.
When my neighbor's turbine began screaching, I took it apart and, after several experiments...adjusting the collars...got it very close to level, both ways.
The screeching is caused by the bearing grease getting squeezed out of the race on the down hill, out-of-level side. The added pressure on the bearings against the race is the culprit, not any design or manufacturing flaw.
I cleaned and regreased the race, checked the caged bearings and put it all back together. It's been eight years since I set it up correctly and it's never made a peep, still working like new.
Many others in the neighborhood have been turning freely, without any noise, for decades.
Edited 5/19/2008 4:12 pm by Hudson Valley Carpenter
Have to differ with you about turbines seizing up.
I've replaced/removed quite a few for either seizing or just getting annoyingly noisey over the years. Probably a small percentage of the ones out there, but it does happen. Some were old and some were fairly new. Like most anything else, the quality varies from brand to brand.
Personally, I think they are hideous and uneccesarry, but that's just me. http://grantlogan.net/
But you all knew that. I detailed it extensively in my blog.
They work well and the newer ones run on virtually indestructible needle bearings. Mine's never been lubricated and it's silent as the grave still after 13 years.
But yeah, they can be urgly on a residence. Which provides the HO with a perfect reason to build a lovely louvered cupola to hide the turbine....
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Personally, I think they are hideous and uneccesarry, but that's just me.
That's very close to what your wife says about you, but just you. ;-)
I put one on the old garage here, because it had an unvented hip roof and got very hot inside on summer days. I would avoid using them on the house because they're not the best answer, and because they're too industrial looking for me.
That's very close to what your wife says about you, but just you.
Your wife never mentions you. http://grantlogan.net/
But you all knew that. I detailed it extensively in my blog.
Neighbor across the street just removed his. The noise was driving his wife crazy.
(And most authorities say they're no more effective than simple vents.)
Not sure what you mean by "half round" vents.
(And most authorities say they're no more effective than simple vents.)
And nine out ten dentists agree that Crest fights cavities.
Our lower pitch Ranch style home has gable vents, but the attic was hot due to open eves with bird-boards blocking any soffit venting.
I did put a power vent in that was sized for 1,800 sq. ft house. It would automatically turn on when the attic heat increased and it would run until past midnight.
When we re-roofed, I took out the power vent and put in four 12" externally braced whirly turbines. They've lasted 14 years without a squeak or problem until they were pounded with golf ball size hail. Even with more venting from the turbines, the heat is still high in the attic.
So this time, after a hail storm has caused the roof to be replaced, I'm going to remove the whirly turbines, take out the bird-boards, and enclosed the overhangs while adding soffit vents. I'm adding a 60' long Cobra 3 ridge vent. Here's some of their "Propaganda".... ;>)
http://www.gaf.com/Content/GAF/RES1/ROOF/CobraRigidVent3.asp?viewer
Bill
Edited 5/19/2008 2:20 pm ET by BilljustBill
A bit off the topic ... but the main reason I find an attic to be poorly vented has nothing to do with the exhaust vent. Gable, ridge, turbine, electric fan, it doesn't matter .... if there isn't enough fresh air entering the attic to replace the air that leaves!
..So what would be the best method of drawing fresh air into the attic?
Lots of little openings, spaced all around ... and not having the airflow blocked by insulation, piles of junk, or whatever. If you want to get fancy, you can have a bias toward placing the vents so that the air will tend to flow under that part of the roof that gets the hottest. It is the heat that the air picks up that makes the air flow in the first place. Indeed, it is this air flow that makes the turbines spin - not just a passing breeze. This is the same principle that makes a 'false roof' work so well. This is when a second roof is set over the first, with an air gap between - and is left open at both the top and bottom edges. Like in a chimney, air is drawn through the channels, removing the heat before it makes it to the real roof. In my own home, I've modified this idea by having vents in the ceiling of each room. Closed in winter, in summer these vents let hot room air continue into the attic - then out the attic vents. (Keep in mind that Nevada is arid, and our 'swamp coolers' depend upon a constant supply of dry air to be effective).
Tests show they are not much more effective than a regular vent of the same area. They also work best during the time when you least need them, and not on still hot days when the roof is most likely to heat up.
I'm a little confused by what the whole house fan has to do with any of this. Does it vent into the attic?
Yes, my whole house fan vents into the attic (as they all do I believe) and out of the attic through the vents. The problem, I think, is that the air circulates in the attic rather than being expelled through the vents.
I didn't know that. It sounds like a bad idea. Our code precludes any venting from the house into the attic. You can't even supply air to a fireplace.
It's SOP for a whole house fan. The air from the house helps to cool the attic, so there's a double benefit.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell
If the air goes into the attic (due to the fan) it's gonna come out. So long as there are no serious air leaks back into the house it'll go out the vents. More vents is better, of course, but any non-trivial arrangement of vents will do the job. Doesn't matter whether high or low.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell