I’m planning for a new roof and considering metal for longevity. I’m also thinking it might be a good time to install an attic fan or two. Thinking of solar powered units as these seem popular. I would prefer something I can easily replace or service myself down the road without getting on the roof, but it appears solar units won’t permit that. I’m in Austin, and it gets hot here, so the attic could use some powered assistance. Anyone have experience with these? Things to look out for, things to avoid? I want a long life from them so the hassle of maintaining them doesn’t outweigh the benefits. Looks like some use brushless motors. Not sure if the solar panels themselves integrated with some units can be replaced or if the whole unit is swapped.
Attic Fan?
- Thread starter xspeedy
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I'm curious if you're saying that a continuous roof vent is not sufficient in Austin.
Big no !
They really don't do much to lower attic temps.
Attic fans suck conditioned air from the interior living space of the house into the attic. This sucking pulls hot-humid or cold-damp exterior air into the living space of the house.
Adding more insulation on top of your ceiling and sealing off around penetrations in the ceiling are better bang for $$.
Seal leaking attic air ducts (Almost all Texas homes have the HVAC system in the attic) is also a great idea.
The ultimate decision would be to create a conditioned attic by using spray foam. That way your HVAC system is brought inside the conditioned area of the house. That's expensive.
They really don't do much to lower attic temps.
Attic fans suck conditioned air from the interior living space of the house into the attic. This sucking pulls hot-humid or cold-damp exterior air into the living space of the house.
Adding more insulation on top of your ceiling and sealing off around penetrations in the ceiling are better bang for $$.
Seal leaking attic air ducts (Almost all Texas homes have the HVAC system in the attic) is also a great idea.
The ultimate decision would be to create a conditioned attic by using spray foam. That way your HVAC system is brought inside the conditioned area of the house. That's expensive.
Wind powered roof turbine type vents work very well, are cheap and easy to replace when needed .
I replaced mine after 24 years, one started making noise, easy job.
I replaced mine after 24 years, one started making noise, easy job.
That depends on the house type.
i use a typical electric roof ventilator, its on a thermostatic control but i bypassed it to a standard light switch so i can turn it on or off as I like! when the motor dies you can just replace it + leave the metal thru the roof, just be sure to buy the same!!
When Mom's house was reroofed the rep recommended removing the existing fan and adding some extra mushroom vents to keep the air circulating. YMMV, of course.
I should clarify this is a 2,200 ft single story house with an attic above the garage and living area. It is strictly attic with a hot water heater and the HVAC up there. There are the normal ridge vents, but it gets really hot up there. I haven’t measured temps, but it feels as though a fan could help some. I get it needs a fan that can support a good volume of air given the space.
Does the house have soffit vents?
In order for ridge vents to work correctly, you need soffit vents.
On my recent reroof, I stuck with whirlybirds.
My house also has gable vents.
Recommendations vary by region. Attic fans are very controversial. Attic ventilation can be more complex than imagined and not as simple as one thinks. I.E., just adding attic fans can be detrimental if the rules are not followed.
Here is one primer article when I Googled "attic ventilation in Texas": https://www.inspections-of-texas.com/5-things-you-need-to-know-about-attic-ventilation/
Also Google "attic fan mistakes": https://www.homepreservationmanual.com/attic-fans-why-they-dont-work/
Here is one primer article when I Googled "attic ventilation in Texas": https://www.inspections-of-texas.com/5-things-you-need-to-know-about-attic-ventilation/
Also Google "attic fan mistakes": https://www.homepreservationmanual.com/attic-fans-why-they-dont-work/
The new thing being adopted slowly in hot climates is to cool the attic space, don't insulate the ceiling in the living quarters, but insulate the roof deck.
Yes, I didn't want to bring that up for fear of sending the OP into analysis paralysis.
Google "sealed attics in hot climates".
I have two 20W solar attic fans that work quite well in combo with the well ventilated eaves. I installed the solar fans when I built the house in 2002. I also have a white concrete barrel tile roof. The combo is epic good with regard to a cool attic. They are near the peak of the roof on the West side, configured so the panels are horizontal.
In the attic between the trusses, I screwed in 2x4's that form a ladder to climb up to the fans, as they are about 15 feet up. Makes it a simple matter to replace the motors about every 10 years. The brushes wear out over time. They are quiet and move quite a bit of air.
The roof is considerably larger than it looks in this pic. The back quarter is 40 feet deep and 65 feet wide.
My eaves are much like this, with perforated panels 100% around the house.
In the attic between the trusses, I screwed in 2x4's that form a ladder to climb up to the fans, as they are about 15 feet up. Makes it a simple matter to replace the motors about every 10 years. The brushes wear out over time. They are quiet and move quite a bit of air.
The roof is considerably larger than it looks in this pic. The back quarter is 40 feet deep and 65 feet wide.
My eaves are much like this, with perforated panels 100% around the house.
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I wouldn't say a big no, but Id say it probably wont help as much as one would hope, and agree it could take you backwards of you do it wrong.
It can work well under certain conditions that may or not exist in a given scenario and they usually don't.
They CAN suck air from the house if one doesn't have the requisite available square feet of open ventilation, but if you do, you wont depressurize the attic and suck from the house.
But what are you pulling in really? If your soffit vents, or openings aren't on the shaded side of the house you could simply be sucking in 140 degree air displacing 150 degree air.
The solar ones didnt make much difference for me as the greatest temp delta comes at night when they dont run.
Im my climate a whole house fan has been an utterly fantastic addition to my climate control simultaneously cooling the house and the attic.
I put two of these electric fans on my roof and instaled some inlet vents around the eaves. They flow 46,000 cu/ft per hour each. So, they can change the air in the roof space in only a few minutes. They have lowered the summer living space temps from over 100 degF to a pleasant 75degF.
I’ve installed radiant barrier this year (in February) and it really helped lowering the attic temps. I’ve seen the drop of ~15-18 degrees. Similar to your house, evaporator and ductwork is in the attic, seen much better AC performance this summer with lower attic temps. I’ve used Attic Foil, took me about a week 5-6hrs/day. It’s not a fun job, but was well worth it
Those are kind of neat! I like it.
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