Solar attic fans?

[Romanova]

Anyone have any luck with them? Thinking about getting one for the house to help the AC unit during the brutal Houston summers. Was curious if they make that big of a difference?

It will be for a 1700sqft single story house.

Thanks!

 

[hydramatic]

A ridge cap running the length of the roof will help it breath thru your soffet vents, if the soffet vents arn`t stopped up with insulation. your still looking at 140 in the summer time up there.

 

[willysrule]

I have a typical 115v four blade 12” diameter fan in the roof, no ridge vent but good soffet vents…it’s hooked up to a Thermostat/Humidistat controller...works great…I have it set on the low side of the recommended setting for the controller (don’t remember exactly what they are)

I thought about the solar one but a few things turned me away from them…
1.) Cost, they are at least triple what my one cost for a good one.
2.) Parts, parts for mine are easily found and relatively cheap.
3.) Only runs with sunlight on it, mine will run most of the night after a 90* day

 

[Falcon67]

It's no big deal here to see underside roof deck temps in the 160F range in summer. I researched ridge vents, whirligigs, solar and passive. I went with passive on the back side because most of the reports gave poor marks to the rest. Here, the wind blows like hell and with a ridge vent, it may actually try push air into the roof or at least block convection. Our house faces south, and prevailing winds in summer are S-SW. Wind has been running mid 20s last two days, gusts to 35+. Normal stuff. I used 5 vents over 1600 sq ft, placing them under 2' down from the ridge where I could. Some are down slope on hips because the roof has several weird hips. Our old house had no eve vents. It had gable vents and 7 passive vents near the ridge. Attic temps never got much past 120F. The garage used only gable vents and temps ran 140F up with the deck 160+.

 

[Cobra6]

I have seen a lot of problems with "too much fan" or ventilation - where it pulls too much in a house and pulls all the pollen, dust and extra junk in through other openings.
If you put in a fan, you need to calculate the cfm and cubic feet it is ventilating.

I decide to go with this -
http://www.adoproducts.com/provent.html

and I am going to use a foil something like this -
http://www.atticfoil.com/flat-top-instruction.htm

and if I do need insulation -

but I am using ProVent instead of his foam strips

 

[JCQuick]

I put one on my house I built 6 years ago. it is the type that you cut a big hole in the roof and you screw it down. I did that part before the put the shingles on. I think it helps.

 

[ddawg16]

I used to have a 110V powered fan in the attic.....It didn't do any good...

Depending on your location, ridge vents or passive is really the best way to go.

There is a formula that explains how much soffet vent you need per sq footage of roof....the vents on top need to be at least the same if not more.

In a proper system....air enters at the soffet, travels up the inside of the roof and out the top.

Properly vented....hot air will flow out the top with little effort using natural convection...no use adding power to it.

Side note....my house has gable vents at each end....per current methods....not the best way. I will be removing them in the near future and closing them up...and installing more vents on top. The problem with the gable vents is that it gives air a short circuit and tends to not alow air to enter in through the soffets....

 

[Falcon67]

There is a formula that explains how much soffet vent you need per sq footage of roof....the vents on top need to be at least the same if not more.

I looked that up when I bought vents. After walking around the house, counting the soffit vents and figuring the vent area, the formula said I needed 21 vents with 9" holes in the roof.

I went with 5.