attic ventilation

My attic gets very hot, even with 3 turbines. Although it is very hot outside (temp about 99-102), an AC service man recently said that my attic is still hot considering that all 3 turbines are working properly.
The house is mostly brick and I have vinyl siding over the wood (veneer?).
I'm wondering if the siding is preventing the attic from getting proper outside air flow. The original outside vents were removed and covered when siding was installed; the siding does have some venting holes.
How can you tell if the attic is getting proper ventilation??
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I live in Phoenix and the attic fan is set for 140 degrees. Ya all know how cool it is in Phoenix this time of year. It turns on in the mornings and shuts off 2-3 hours after sun down.
I can honestly say that I have notice no difference in the attic/home since installing the fan. Other than the noise it makes.
I am into passive ventilation instead of forced air for the attic.
Call a insulation company and have another layer of insulation added and forget about it.
I had a home built in 1999 came with R-30 I bought the home in 2004 I added R-19 all over the house and R-30 over the garage. A/c bill dropped in half of the previous owner's high bills. My brother had a similar home and did the same and he even noticed a difference. The cost was less than doing it ourselves.
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In alt.home.repair on Mon, 25 Jul 2005 12:01:09 -0700 "SQLit"

I know you live in Phoenix, and I live in Baltimore, where it isn't so hot, but 140 strikes me as high. It's been 22 years, but I vaguely remember mine being set to 120 when I opened the box.
That doesn't meant to me that my attic is never hotter than 120. I've thought about raising the temperature setting, but but I figure as it is, the fan goes on earlier, and doesn't fall behind so soon, and the attic stays less hot most** of the day than it would be if it turned on later. I figure it goes off later, when outside air is cooler, so the attic is left cooler when the fan goes off.
**It's not the maximum temperature of the attic that matters, imo. It's the average temperature. So even if it is over 120 or 140, the less time it over those numbers, and the lower it is at any time, the less heat will be absorbed by the attic floor and transmitted to the living space beneath. Whether there is lots of insulation or none, there will still be a difference.

Mine turns on iirc between 12 and 2 and off by about 10. And that's in 95 degree weather with a dark brown shingled roof. With hotter temps in Phoenix, maybe yours should go on by 8 o'clock and off 3 or 4 hours after sundown. What time does the outside become cooler than the inside?
Of course I think one doesn't want to turn it on too early. I've been up in the attic at dawn when it was very hot the previous day, and it's never hot at dawn the next morning. So I wouldn't want to turn the fan on at 100, I sort of think, if it was already 110 outside. But I don't think that could happen with a brown roof. What about a white or light colored roof?

If you use AC, it will be hard to tell the difference. When I installed mine, I wasn't using AC and it took 10 degrees at least off the temp of the second floor, below the attic. It went down from 95 or 90 to 85 or 80. Maybe as much as from 95 to 80.
Without the fan, I could not bear to go upstairs even for a couple minutes, after I got home from work, 5:30 or later if I stopped. I slept in the basement and went up in the morning to shower and get fresh clothes. After I installed the fan, I slept in my bedroom all year long. (I hesitate to mention this, but I sleep naked and without a cover. Both before and after installing the fan. I've found that it can be 10 degrees hotter at the same level of comfort, if I don't cover myself with a sheet or anything.)

Interesting. I"m not sure frankly what I have in the attic.
Did they have R-30 in 1980?

Meirman -- If emailing, please let me know whether or not you are posting the same letter. Change domain to erols.com, if necessary.
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Probably a good idea for you. I just did not want the fan running 24/7 all summer season. I also had turbines. It was just a number that I picked. My fan was purposely over sized but not by enough. I believe if I ever install another fan I would be a 2X the air recommended.

I believe it is the thermal invasion from the attic to the conditioned areas of the home. High or median would make little difference. That is where the blanket of insulation come in.

What time does the outside become cooler than the inside?
Last night it was triple digits until 22:00. It was 85 F this morning

They had it, they did not install it. 1980 where I live they would have been using ~ R-24. My curent house was built in 1979 and R-19 was installed. As soon as I get the rest of the wiring and plumbing done I am calling the insulator.
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As a guess, it's possibly not getting proper ventilation. You seem confused as to how the attic might be ventilated. Like, from soffit or eave vents, or hatchway. Vents under siding? Not likely, but tell us about area and airflow path. And ... what do you mean by "turbine" if other than axial-flow fan? Powered? Passive?
One of the best ways to cool a house is to shade it, with whatever trees possible to the south and SW. Porch shading can be very effective, too.
To check flow, you could simply calculate anticipated flow rate through fan (cfm/flow-area = ft/min flow rate) and see how close it is.
HTH, J
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I don't have an answer for your question, but it also reaches 100+ degrees where I live, and I leave the attic door in the ceiling my garage cracked open during the summer to help improve circulation.
stevie wrote:

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stevie wrote:

Well attics do get hot.
My only question is how many square inches of inlet (low vents in to soffits or gable ends) do you have and how many square inches of high vents (your turbines plus whatever) do you have? You have to have someplace for the cool air to come in.
--
Joseph Meehan

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The turbines provide excellent ventilation, although they will need periodic maintenance. Check for open soffit vents and clear out insect nests, insulation, debris, etc.
Calculate your attic floor space and multiply by 0.4%. The result should be the minimum total ventilation area (intake plus out). With triple-digit summer temperatures, I'd increase the percent to 1%.

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The turbines are at the top, near the ridge. That's where the hot air escapes. Now, where does it enter? There should be vents in the soffits under the eves. Make sure they are not covered, inside or out. A well ventilated roof will make your shingles last longer, may reduced AC costs, and will prevent ice dams in winter.

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In alt.home.repair on Mon, 25 Jul 2005 12:56:09 -0500 "stevie"

No, veneer is wood glued to wood. Most furniture is made of veneered wood, or for short, veneer. They use pretty, probably expensive wood, and glue it to cheaper, less pretty wood. I guess even particle board can be covered by veneer,
And I supppose some might call particle covered by Formica, or something else that isn't wood, veneer, but I hope not.

The siding, no.

In that case, yes.
Ignore the no.

Are then as big as and directly over the original outside vents?
Where were the original vents? In the soffitts (under the eaves)?

If it is not hotter than other attics, with the same weather outside.
That's the bottom line, although measurements of the amount of venting will probably tell you how far away you are from where you should be.
BTW (addressed to you and others here), don't turbines work only when there is at least some breeze? I must admit, I'm confused about why they are turbines. I guess if there is no breeze, the air is still supposed to rise and as they pass through the turbine, they set it spinning. What is the point of that? Why not just have a hole in the roof with a cap to keep out the rain, and a place for the air to escape sideways, in all directions, under the cap?
Wouldn't the energy expended to make the turbine spin slow down the exit of the hot air? Of course you have 3, which I guess would make up for that.
Meirman -- If emailing, please let me know whether or not you are posting the same letter. Change domain to erols.com, if necessary.
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
wrote:

Veneer is very thin lumber! ;->
-----BEGIN PGP SIGNATURE----- Version: PGP 7.1
iQA/AwUBQufLsAIk7T39FC4ZEQIdnwCeNRxFp3y0Gv04eHBrNs2w7IdVSfMAoME9 3k5OjNVcQStploSTfyzIiFPD =sxUR -----END PGP SIGNATURE-----
--
-john
wide-open at throttle dot info
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guys,
I have been researching ATTIC heat invasion in the past 3 months. ( i am in TEXAS)
some findings.. when the temp outside is 100F.. the roof shingles are reaching 135 -140 F... now the inside roof temp is 130-135 F... and the attic floor or surroundings is also. 120-130F...
I have started installing a Radiant Barrier which I purchased a TRIAL roll 500 sf ft for 80$ from here
http://www.afs-foil.com/radiantbarrier.html
and I am impressed with it.. becuase.. the area underneath the barrier is 100F while others remain the same i.e 130 F
a rule of thumb is that around 30% our Electricity bill is from AC costs .. and 30% of AC costs is cooling the heat invasion from the Roof.. so.. it should get me a 9% savings ROI in my monthly peak bills.. but I found lot of interesting research saying that it cud be anywhere from 2% to 15%.. lot of factors.. first of all I dont have access to all portions of my attic or there is no attic space over the cathedral Living and one BDR.. also. I dont have any TURBINE vents.. or any vents.. need to get that installed too
http://www.ornl.gov/sci/roofs+walls/radiant/rb_01.html
also..i have 2 HVAC units and both are in the attic so I think I will save a bit there.. as they are all going to be 30F cooler...
BTW, I bought the 25 inch roll and am stapling it underneath the rafters.. and it is taking me around 100 Sq feet per 2 hours or so.. trick is to get as much covered up as possible.
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In alt.home.repair on 27 Jul 2005 13:40:04 -0700 snipped-for-privacy@hotmail.com posted:

A friend with a cathedral ceiling has iiuc, 2 feet of attic space there. Either there was an opening, a door, or he cut one, to put in some lights. This is Baltiore. Contrsuction might be different in Texas.
Arthur, maybe this will help you. Maybe not, but I'm sending it.
also. I dont have any TURBINE vents.. or any

Meirman -- If emailing, please let me know whether or not you are posting the same letter. Change domain to erols.com, if necessary.
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posted:

Most brick construction around here is called "brick veneer" -- a non-structural facing of brick over convential wood framing.
One can have veneer crowns of porcelain placed over one's teeth.
One may even have a veneer of attitude about one's person -- "a veneer of self-confidence," for example.
I have now seen a second house roofed with a ridge vent for ventilation -- and no soffit vents. A neighbor's roof was done that way, and now a friend is buying a townhouse that was recently reroofed (the whole complex was reroofed), and the ridge vent is visible, but there's virtually no roof overhang, no place to put a soffit vent, so they didn't bother. Parts of the unit with an attic has what I'd call gable vents if they were in gables, but I've warned the friend that I expect the '70s style cathedral ceiling in the living room is going to get very hot, and his new neighbors have confirmed that.
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In alt.home.repair on Thu, 28 Jul 2005 01:17:47 GMT "Robert E. Lewis"

Point noted. Thanks to you and Johnny.

of the roof?
I can almost imagine that a ridge vent alone would allow hot air to escape from one end of the ridge, while outdoor air which is colder and heavier fell into the house though another end, or part, of the ridge vent, but people seem to say that doesn't happen or happens very little.
I can also imagine the hot air sitting inside the roof and barely getting out because of the colder air on top of it that holds it dowsn. Individual molecules would escape, but that would be maybe 1% of what would leave if there were a fan to blow the air out, or even good circulation.

Meirman -- If emailing, please let me know whether or not you are posting the same letter. Change domain to erols.com, if necessary.
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posted:

I have suggested to the friend buying the townhouse that he put in some sort of roof vents over the part of the with an attic (one of the gable vents set up high in a wall in the attic space seems to be almost directly above the outdoor condenser unit of the central a/c, so I imagine it may be sucking hot air into the attic in summertime). Some of the other units have roof vents (none seem very low on the roof) in addition to the fairly short section of ridge vent, so apparently the condo management does allow that.
I don't know what sort of retrofit my friend might be able to do to the roof over the living roof, where there's a sloping ceiling and no attic (not even any ridge vent there -- the roof slopes up, is interrupted by an atrium, then resumes it's slope on the far side, where the ridge and ridge vent are located). I'm guessing the condo association, when the roof was replaced (within the past two years) did not install a radiant barrier.
On the neighbor's house, I suggested she make the roofer come back and put some soffit vents in (he did some patching of soffits and fascia, IIRC). I don't think the neighbor understood the basic heat-rises principles of soffit/ridge venting, so she had him come back to re-work some unsightly flashing and nothing else. (sigh)
--

Robert




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stevie wrote:

Put one or more digital indoor/outdoor temperature sensors in the attic and put their displays in the living area so you can easily read the temp in the attic. I think you can get ones that are wireless nowadays. Or you can drill a hole in the ceiling in a closet or route a wire down through a wall.
If you want to get fancy, you could try something like http://www.electronickits.com/kit/complete/meas/ck110.htm
As another poster indicated, make sure you have enought inlet so that the attic can breathe.
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Matt wrote:

WallMart has a variety of digital wireless thermometers, especially at Christmas. Should be able to get the main thermometer plus one remote for $15-20. They are extremely handy for checking a variety of appliances and conditions. Uses include checking the freezer, the freezer compartment of the refrigerator, main compartment of refrigerator, attic, garage, inside the parked car, inside your storage shed, etc.
Most have a high and low temp memory but have to be manually renewed.
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