Atticbreeze Solar Fans
Currently I do have a house fan and two gable vents plus a turbine fan (non-powered) the turbine fan doesn't really do much at all. The second floor is always stifling hot if you don't have the Aircondition on. Any help would be great.
Comments
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Re: Atticbreeze Solar Fans
You shouldn't need any attic fans. Houses can be ventilated naturally without having to draw power. Too often they aren't, though. You should get your venting and insulation evaluated and fixed if at all possible. It will save you money long-term on heating, cooling, and running attic vent fans.
I'm just whining like this because I'm taking a break from working in an attic at 40 C where the insulation has been "blown in" until it's blocked practically every vent in the place. Mostly I'm repairing wiring that was done by some moron, but I have to clear the vents as I work too. It's amazing what happens when you push the insulation back and let the air flow in! -
Re: Atticbreeze Solar FansCariboocoot wrote: »You shouldn't need any attic fans. Houses can be ventilated naturally without having to draw power. Too often they aren't, though. You should get your venting and insulation evaluated and fixed if at all possible. It will save you money long-term on heating, cooling, and running attic vent fans.
I spoke recently with a house inspector, and he said
the very same thing. A properly ventilated attic should
not need an attic fan. According to him, the well-
designed attic will have soffit vents for air intake and
roof peak vents for air exhaust. Convection will then
cause a self-sustaining air flow.
He said the proper design will create no more than 10 degrees
difference between the outside air and the attic. When
you measure the outside temperature, he said to do it
by placing a standard thermometer directly in the sun,
i.e., it gets the same conditions as the roof top.
My home came with two gable vents and no roof vents.
I added three roof vents later myself. Even with the
roof vents, it was way more than 10 degrees hotter
in the attic.
I later put in an electric attic fan, which turns on when
the attic reaches specific temperature or humidity.
I can stand below it outside the house, and can feel
the heat pour out of it when it's on. Nevertheless, my
expert friend says I am wasting money on that fan and
should instead fix the venting. -
Re: Atticbreeze Solar Fans
some homes are normally hot and it is usually the much older brick homes from before 1950 or so. you could try rigging a fan on an extension cord to push air temporarily up and out of the highest vent to see if it actually lowers the temperature not only in the house, but the attic too. if you see no improvement in an hour or so it most likely won't benefit you. i have tried to cool my place with fans in every conceivable place even when the outside ambient air was as low as 64 degrees f and it still didn't pull the inside temps down. my home is 100yrs old and a 3 story of double brick construction. in my case it may be a backdraft circumstance as i have not completed remodeling. this can occur when there's hot air up high and cold below with an inlet up top for hot air on the roof to enter and an outlet near the bottom letting cold air escape thus pulling the hot air downward. obviously, a home doing this is not air tight and no amount of insulation will change a backdraft from heating the upper living spaces. you may say that this doesn't make any sense because hot air rises, but cold air falls too and when there's thinner outside heated air the cold air inside the home will pour out near lower levels and pull that hot air in from the higher levels.
during the winter the air outside is colder and denser so this backdraft can't happen then and the normal way of thinking hot air rises and is allowed to happen because the cold air is pushing in from the bottom. this makes a home hotter in summer and colder in winter than it should be.
don't get me wrong here as you still need good insulation, but it won't stop what i just described from happening. -
Re: Atticbreeze Solar Fans
Attics SHOULD vent on their own, but that assumes you don't live in H*ll -- which includes certain parts of Texas, Arizona, New Mexico and Southern California.
In some places there is simply too much heat coming through the roof for any amount of natural convection to work. In those cases an attic fan, or better still more insulation, is the only solution.
Remember -- our solar panels aren't 100% efficient at turning sunlight into electricity. A roof is much closer to 100% efficient at turning sunlight into heat -- and unless you gots lots of monies, you probably have more uncovered roof than covered ... -
Re: Atticbreeze Solar Fans
Air movement is difficult to get a handle on, that's for sure. Especially after the house has been built. It's easy to put additional vents in the wrong place too, like on opposite sides of the peak at the same point (blows in one, out the other, drafts nothing from the eaves).
You know what works good in hot climates? Concrete roof tiles. Of course you have to build for that too. -
Re: Atticbreeze Solar Fans
I have 4 solar powered attic fans on my story and a half house. After installing them it felt much cooler upstairs. I think that active ventilation is better than passive ventilation especially when the energy to actively vent is free.
Having had plastic attic vents degrade over time, I used fan/vents from Natural Light mainly due to the metal construction and quality of the finish. -
Re: Atticbreeze Solar Fans
Sort off the OP, but here in the South there is a move toward a sealed attic, with insulation under the roof deck, foam preferred.
This keeps the attic cool, cuts cooling cost. I first saw such a build in 1969, when we had to do repair work in an attic, and was forever impressed by the cool temps we worked in that July day. -
Re: Atticbreeze Solar Fans
Not to mention that since many houses have HVAC ducts running in the attic, insulating the roof also minimizes duct losses which can be very high if the ducts are not insulated/sealed as well as they should be. -
Re: Atticbreeze Solar FansSort off the OP, but here in the South there is a move toward a sealed attic, with insulation under the roof deck, foam preferred.
This keeps the attic cool, cuts cooling cost. I first saw such a build in 1969, when we had to do repair work in an attic, and was forever impressed by the cool temps we worked in that July day.
I talked to a foam insulator this week on my new construction and he recommend doing exactly that. Actually he suggested in the 2X6 wall cavity to do 2 " of closed cell foam and then 3 1/2 of fiberglass bat. There was a point of diminishing returns adding more foam than 2 inches for a incremental step in cost. Then no attic vents and foam the underside of the roof deck. He then suggested a heat exchanger/air makeup because the building is so tight. -
Re: Atticbreeze Solar Fans
After several months of lurking, finally my first post for a subject I have been messing with!
I do live in one of the extreme heat areas. West Central Florida.
After finishing new well ventilated soffits, had to try something else.
Went with a 16" Venturi 12/24v gable fan connected to HF 45 watt kit.
Our current ridge vent is useless here, since we have no wind, not even a slight breeze, and heat convection alone is not enough to move the air through the attic.
Tested temps before, then after installing fan and plugging ridge vent (used 2" compressible foam strips that could be removed later if desired). End results were not great, but better than nothing. Attics temps dropped 7 to 12 degrees peak.
The HF kit is the newer one with numeric display and USB port. They now lowered the specs on the box to 2.5a (if I recall correctly), yet I did see 4amps several times during testing before installation.
Connected the HF kit to a small motorcycle battery. This was a new AGM battery that I received as a warranty replacement to one that failed shortly after purchase. Due to reliability, will not use on bike, so solar makes a great use until it is destroyed. Fan is running off charge controller 12v output instead of panel direct for a couple reasons. It only draws 1 amp at 12v. I used a thermostat as a timer to turn fan on at 8am (bypassed thermistor with a resister to a fixed temp), so it keeps things cooler before roof mounted solar normally would have, and shuts off fan at 9pm, to continue cooling a little after sun goes down. Running the fan at a fixed 12v will prolong motor life, and keeps it going at same speed, even during cloudy days.
So far after 3 months use, it all is working as expected. Not really worth it from a money point, but to get into solar with little cost and some benefit, I would do it again. -
Re: Atticbreeze Solar FansAfter several months of lurking, finally my first post for a subject I have been messing with!
Welcome to the forum!Our current ridge vent is useless here, since we have no wind, not even a slight breeze, and heat convection alone is not enough to move the air through the attic.
I think the theory is that the difference between the temperature
at the top of the sunlit roof and the usually shaded soffit vents
should be sufficient to drive a convection current. In other words,
wind is not supposed to be necessary.
But I wouldn't be surprised that what current there is isn't enough.
Attics are just so hot, and your being in Florida means that you
have a huge radiant heat load to shed.Attics temps dropped 7 to 12 degrees peak.
Being analytical, I like seeing data. Thank you for measuring and
reporting it! I'm sure that was a sweaty task.
I did some recent temperature measurements myself. However,
mine were done on the outside :-) of the attic. The numbers
below feed into a question I've always wondered about, that is,
what is the "R factor" for roof mounted solar panels? I used a
Black & Decker IR thermometer for the roof measurements.
Location is St Louis, MO.
Air temp: 95 degrees
PV module temp: 118 degrees
Exposed roof temp: 145 degrees
Shaded (by panel) roof temp: 124 degrees
--
With 13 PV panels, that is about 150 sq feet of shading, for
a 1200 sq ft house with a standard angled roof. Let's say
that represents 10% of the roof being shaded?
I didn't take before/after measurements inside the attic, so
unfortunately I can't tell whether there was any insulating
effect from the PV modules. I'd like to hope that a 21
degree drop over that amount of area would have some effect
inside the attic.
By the way, I have a conventionally powered attic fan that
is mounted over one of my gable vents.
John -
Re: Atticbreeze Solar Fans
Air temp: 95 degrees
PV module temp: 118 degrees
Exposed roof temp: 145 degrees
Shaded (by panel) roof temp: 124 degrees
that seems as if the exposed areas of the roof are absorbing the heat and sending quite a bit of it into the attic area. it is being reradiated from the inside out in the area the pvs are in and might explain why the roof that is shaded is 6 degrees warmer than the pvs are. it would be interesting for a comparative measurement from inside the attic when outside conditions match that of your above measurement. -
Re: Atticbreeze Solar Fansthat seems as if the exposed areas of the roof are absorbing the heat and sending quite a bit of it into the attic area. it is being reradiated from the inside out in the area the pvs are in and might explain why the roof that is shaded is 6 degrees warmer than the pvs are. it would be interesting for a comparative measurement from inside the attic when outside conditions match that of your above measurement.
John - how hot are your inverters getting in that heat? -
Re: Atticbreeze Solar FansAir temp: 95 degrees
PV module temp: 118 degrees
Exposed roof temp: 145 degrees
Shaded (by panel) roof temp: 124 degrees
that seems as if the exposed areas of the roof are absorbing the heat and sending quite a bit of it into the attic area. it is being reradiated from the inside out in the area the pvs are in and might explain why the roof that is shaded is 6 degrees warmer than the pvs are. it would be interesting for a comparative measurement from inside the attic when outside conditions match that of your above measurement.
My guess as to why the shaded roof is hotter than the PV panels is
that the panels are being cooled more by prevailing air current than
the roof is. The PV panel has wind cooling both sides of it, whereas
the roof has only on its top side cooled.
I agree that the underneath roof being hotter than the sun-exposed
PV panel can mean it is getting subjected to re-radiated heat, too, as
you suggest. I hadn't thought about that, but that makes sense.
There's probably some effect from mass and material properties
with regard to how much heat these items can hold. The roughly
2'x3' solar panel weighs 44 lbs. I bet the same size roof, consisting
of shingles, nails, wood, and some moisture is heavier than that.
Drees, I didn't check the inverter temp, but I will sooner or later.
I have to go around to the other side of the array to access
those, and, well...I didn't want to fall off the roof, as there is only
a one foot channel around the array ends. Falling off your roof
to measure a temperature might get you nominated for a Darwin
Award.
John -
Re: Atticbreeze Solar FansDrees, I didn't check the inverter temp, but I will sooner or later.
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Re: Atticbreeze Solar Fans
I would take a serious look at radiant barrier insulation, we use this in Phoenix and see great results in sommer months lowering attic temps as much as 25 degees.
http://www.sunriseenergynow.com -
Re: Atticbreeze Solar Fans
Reflectix is available at Home Depot:
http://www.homedepot.ca/webapp/wcs/stores/servlet/CatalogSearchResultView?D=902359&Ntt=902359&catalogId=10051&langId=-15&storeId=10051&Dx=mode+matchallpartial&Ntx=mode+matchall&N=0&Ntk=P_PartNumber
Also this version:
http://www.homedepot.ca/webapp/wcs/stores/servlet/CatalogSearchResultView?D=902354&Ntt=902354&catalogId=10051&langId=-15&storeId=10051&Dx=mode+matchallpartial&Ntx=mode+matchall&N=0&Ntk=P_PartNumber
I've used it. It works moderately well. The usual hyped-claims in the advertising, of course.:roll: -
Re: Atticbreeze Solar Fans
The nice thing about the reflectix is that it does have a bit of insulative value above it's reflective properties as well... -
Re: Atticbreeze Solar Fans
I have two of these
http://www.solaratticfan.com/pages/20_watt.html
You can get a circut that turns them off below 75 degrees and they come with a 25 year warranty.
Here is an install of one from home power magazine
http://homepower.com/article/?file=HP112_pg24_Patterson
there is also a few reviews on amazon.
After I had them installed I whent up on the roof to set the pv in the up right postion. I stuck my hand underneath them and it felt like a small blast furnace whith all the warm air being sucked out. Pretty cool if you ask me. Pluss the tax rebate was nice too. -
Re: Atticbreeze Solar FansI would take a serious look at radiant barrier insulation, we use this in Phoenix and see great results in sommer months lowering attic temps as much as 25 degees.
They also advertise this on the sunrise site:
The KVAR Energy Controller reduces the amount of non-productive current in your electrical system, which means a significant reduction in power costs to you. The KVAR Unit fine tunes the electrical system from the inductive utility company’s KVA electric meter, kilowatt hour meter or demand meter. This streamline of energy creates less electrical waste, protects against power surges and increases the capacity to the electrical panel by making it run cooler. All this means extra SAVINGS in your pocket!
Up to 25% savings? BS! You would have to be operating industrial sized motors and be paying for KVAR to come close.
Anyone advertising something like this 'thing' is suspect in my opinion and a party to be avoided! -
Re: Atticbreeze Solar FansCariboocoot wrote: »You shouldn't need any attic fans. Houses can be ventilated naturally without having to draw power. Too often they aren't, though. You should get your venting and insulation evaluated and fixed if at all possible. It will save you money long-term on heating, cooling, and running attic vent fans.
I'm just whining like this because I'm taking a break from working in an attic at 40 C where the insulation has been "blown in" until it's blocked practically every vent in the place. Mostly I'm repairing wiring that was done by some moron, but I have to clear the vents as I work too. It's amazing what happens when you push the insulation back and let the air flow in!
Depends on the climate. In a hot climate like Arizona there's no way in hell you're going to get all the heat out of the attic through ventilation alone. It can climb up to 160 or 170 degrees in an attic out here, and solar attic fans have proven to be tremendously useful. However, if I was say, in Northern California or Oregon, then yeah, I wouldn't consider it and probably think of it as a big waste of money. -
Re: Atticbreeze Solar FansI would take a serious look at radiant barrier insulation, we use this in Phoenix and see great results in sommer months lowering attic temps as much as 25 degees.
http://www.sunriseenergynow.com
I agree, radiant barrier has a lot of studies and backing on it for use in a hot climate although it definitely needs to be perforated and it most useful attached to the underside of the attic roof. Its basically like semi-permanent insulation as the stuff won't settle and is generally warrantied for at least 25 years. -
Re: Atticbreeze Solar FansDepends on the climate. In a hot climate like Arizona there's no way in hell you're going to get all the heat out of the attic through ventilation alone. It can climb up to 160 or 170 degrees in an attic out here, and solar attic fans have proven to be tremendously useful. However, if I was say, in Northern California or Oregon, then yeah, I wouldn't consider it and probably think of it as a big waste of money.
Nope; depends on the house. Even in really hot climes like Texas you can build a house that does not need forced ventilation. Trouble is, this almost never happens. Architects like to drop in whatever design, instead of accommodating the local conditions. Multiple roof facets are one of the worst offenders; they are ripe with "dead air" pockets that inhibit air flow. But not everyone wants to live in a plain rectangular box.
Up here we have the dual problem of Winter snowfall and -40C combined with Summer drought and +40C. Most houses can't handle the two extremes. -
I recently had the Attic Breeze Model 3523-A installed when my roof shingles were replaced. It dropped the temp in the attic 8-10 degrees ONLY after I added additional inflow ventilation. Communication with the manufacturer indicated I did not have enough “net free air” (nfa) flowing into the attic and the 3523-A will slow down the motor if it detects it is drawing negative pressure in the attic. I have under eave Fiber Cement Vented Soffit, like Lowe’s item #214897 model #217516, which provides 5 sq in of nfa per linear foot. The 3523-A requires 5 sq ft of nfa. I estimate the soffits are at best 80% efficient due to debris from installation and reroofing . I will need 180 ft of soffit to meet the minimum requirement. [5 sq ft = 720 sq in. 720 sq in/(80% of 5 sq in) = 180 feet].
I added an 18 in. x 18 in. Steel Return Air Grille (Home Depot Internet # 300539288
Model # E17018X18 Store SKU # 332661) and #10 Mesh 304 Stainless Steel Woven Wire to the front porch ceiling.
On a 94° day in Texas, I measured an 8 - 10° difference in the attic temperature after the grill was added. The measurement was taken 4 inches above the blown-in insulation. This house is 8 years old with six-inch exterior walls. My solar fan is facing South on the roof with the solar panel at 20° elevation facing South.
Additional solar attic fan installation notes:
The attic fan should be 3 feet from any roof edge and 10 feet from any other roof vent. The installers originally had the solar panel fully extended facing North!! So double check their work. And know the best angle for your solar panel where you live. The angle of my solar panel is best for the Spring through the Fall.
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