Agreed. I don't think one should cover them up unless the attic is finished and heated. For some reason, I was thinking of a finished (heated) attic in my original post but didn't say that so it was a misleading statement and not applicable in ALL situations.
Agreed. I've had several homes and I can't say they worked that great either. I won't say they didn't work but I can say it still got hot up there. Nowadays, on the gulf coast (Texas), you see new home construction using ridge vents and soffit vents instead of the turbines.
I don't think that the spinning of the turbines provides much more cooling than just having a hole in your roof of the same size... They probably make a difference compared to not having any opening in the roof... The ridge and soffit vents rely on hot air rising to reduce the amount of heat in the attic... It worked pretty good on my last house... It was still warm up there, but not quite a warm as a previous house that relied on a electrical vent fan... Since the ridge vents are at the highest point in your roof, they'll probably let more air out than some vent that is stuck halfway down your roof face... My last house had significantly more trees around it than the previous one did, so it's not a very good comparison...
I heard of a guy once who installed a sprinkler system on his roof to help cool his house... It was probably most efficient when he set the water flow such that the water would evaporate, but not necessarily drip off the house (latent heat of vaporization), but I think he had it tied in with his gutters so that he could recover the water and reuse it... With the calcium in Houston water, I suspect that you would have noticeable mineral stains on your roof within a year...
Even with RO filtered water, you will get some mineral deposits. Only distilled water is pure enough to spray on the roof without getting mineral deposits.
Latent heat of vaporization gives the BEST heat removal. High pressure misters (160psi - 1000psi) are far more effective at removal of heat as the droplets are so small that they instantly vaporize when they hit a surface. 4 misters at 160psi with a .008 orifice will dispense about 2 gallons per hour.
If you don't understand how they work I can see how you might think that. They work very much like a vacuum cleaner. If you don't believe, go up in the attic and make lots of dust then go outside and watch.
If you build a cupola, it will exhaust all the air you can get into the attic. It will also let more light in, give you a place to hide antennae, gauss-guns, or snipers, and give you easy access to the roof when you have to re-shingle the whole thing because someone put black shingles on an unventilated deck.
I'm just saying with a free spinning roof turbine, the temperature change that I noticed was small enough that I would not be surprised that a hole in the roof of the same size would give about the same result... If it changes from 150F to 140F, you're not really going to notice it while in the attic, you're just going to say that it is FUCKIN' HOT... A power vent is probably a bit better as long as you have sufficient soffit or gable end vents to allow air exchange... No matter what you use, you need air exchange... Someplace for the air to enter and someplace for it to exit...
The OP said that he had insulation just under the roof and along the walls.
Perhaps everyone who has replied to him should examine his answer.
That's why the roof fan that I bought 23 years ago urged owners to install a switch on the floor below, so they could turn the fan on after a hot shower or something that put humidity in the attic. They also urged people to install another switch to turn it off, when the thermostat would turn it on.** They gave a wiring diagram, very simple to use. I used one of those double switches on one box, but mounted the box sideways, so the switches would be up and down.
**I use that in the early spring and the late fall to warm my house with the daytime sun.
That leaves electric roof fans and gable fans, and I can assure you that the roof fans work.
I was only going to reply to the previous post, but I shoudl have read the others first.
I have a very good comparison, because my house had ridge and soffitt vents, full width and the soffitts were not just a few holes in vinyl siding soffitts, but window screen 4 inches wide the whole width of the house.
Still intolerable in the attic, until the roof fan went in. Then 10 degrees cooler in the 2nd fllor and maybe 20 to 40 degrees cooler in the attic.
Moderately dark brown shingles. Changed to moderately light brown shingles a couple years ago. That might mean I use the fan less, but it doesn't affect the temperature in my attic in the summer, except maybe before 10AM because the fan takes care of that after the fan goes on.
Maybe so. But, if he was recovering the water with his gutters, and he had a cistern, maybe he used mostly rain water.
Please. What size attic, fan make and model, how controlled---timer? Most of what I am reading in this group complains that they don't last. What has been your experience in that regard. TIA
I tried to buy the most expensive fan I could find, because I didn't want to have to repair it, but in 1983 there was only about 10 dollars difference in the ones I saw for sale. I bought it at Hechingers, a Maryland area chain that went out of business maybe a decade ago. I guess it would be categorized as a big box store. This was well before Home Depot or Lowes.
I have a 700 square foot house, x 2 floors plus attic and basement. The attic is about 7 feet 6 inches in the middle and tapers to zero at the front and rear. The width of the house is 20 something. From that I calculated the volume and it was smaller than the capacity of any fan for sale, 20, 30% smaller.
I'm sure you can't get my model anymore, and the make is embossed on the cover, which is on the roof. I have the manual, but the house is such that I couldn't find it now. I don't think the brand matters.
Controlled by a thermostat that was included. With dark brown shingles, on the sunniest days of the summer, went on around 10 in the morning and off around 7PM (daylight saving time). On less sunny days, or when the sun is lower in the sky (away from June 21), it goes on later and off earlier.
I have a cutoff so it won't run when I want the heat. On Sunday, it was a bit hot upstairs, and I turned off the cutoff and it started up, around noon. The windows were all open Sunday night and it was cold Monday(53?) so I turned the fan off Usually I don't do this on and off bit. I turn it off in late fall when I get chilly with the windows open and on in early spring when I turn the heat off and later I'm too warm, and I don't give it any other thought. I don't take hot showers and I don't cook a lot of steamy food** so there is no need to turn it on to remove attic humidity.
**Even when I do boil water for spaghetti or something, after it boils, I turn the electric burner down to about 6 out of "10" where it just simmers.Well, it's 22 and half years, and I'm on my 4th or 5th motor. The first one lasted about 7 years, and I sent to the fan maker for a replacement motor. I was probably hot while I was waiting.
The seocnd motor lasted 2 or 3 years! So the next time I went to Electric Motor Repair and bought a replacment there. 75 or 80 dollars, as much as the whole fan had been. But I don't care about the cost. I love the fan.
That lasted 5 or 6 years.
So either my current motor has lasted 7 years or there was another motor I don't recall. I also think one motor lasted 9 years, which makes the one that only lasted 2 or 3 even stranger.
Changing the motor took about 30 minutes the first time, and maybe 15 minutes thereafter. (not counting turning off and on the breaker.) It's done from inside the attic, often just after dawn, and requires forcing the first of three brackets away from the motor. After that it is easy. Putting it back is easy also, even the third bracket for some reason.
Anyhow, I'm happy it started this week. I don't think that guarantees it will last though the summer, but it might last.
The rain lands on the roof and splatters, some of it hitting the screen of the fan. Some of that goes through the screen and lands on the floor. But never enough to make the floor "wet". It's just the attic, but if I kept stuff that could be damaged, I'd put a plastic sheet under it, with newspaper on top, to determine how far the wetness extends. After that I'd get rid of the plastic and the newsppaer and just not put anything that could be damaged in that circle (maybe 3 feet.)
I figure the rain might be damaging the motors, so I looked into putting additional screening where the current screen is, but that fan lasted a 7 years or more, so I put that on the back burner.
I also think maybe I should oil the motor every eyar, and I don't remember for sure, but I'm pretty sure if the motor had places where it is to be oiled, I would notice and wouldn't be wondering. I figure it doesn't have such places and uses oil-impregnated bearings. So I think that means oiling it won't help.
Maybe I could find a motor of the same size with ball bearings?????
I hope I remember to ask next time.
I should save the old motor, so I don't have to extract the current one before I go to the store. I think I did last time, but I didn't label it adequately, so I don't know which motor it is, or where it is.
But all in all replacing the motor is only one errand in town, during working hours, and 70 dollars, and 15 minutes just after dawn. Every
5 years or so on average. That's really not much. In return, I get to use my upstairs all summer with only a couple weeks of AC, if that, in Baltimore, compared to loosing three months of use or using the AC all summer.
Agreed but a lot of people don't want them now in south Texas (typical 95 degree summer days) because it costs money inorder to run them (net savings less) and require eventual maintenance. I used to have power vents and they did work but used electricity and eventually required some maintenance too.
95/95 days are common (95 F and 95 RH), it is MISERABLE, even DANGEROUS in attics that are not well ventilated, 120F+ and high RH. Got to get in and out FAST and be WELL hydrated with Water, not Cola, Tea, or Coffee when going up there to maintain a power vent.
Ridge and soffitt just eliminate the need. We all have to replace the roof sometime, do it then. Ok, in cooler climate, a powered vent solves the problem and cost MUCH less to buy and install.
easy to
They work but eventually they will require some maintenance and you will be paying for electricity to save electricity.
Your question makes sense but I can't answer that without knowing more facts. Probably best to ask some local a/c guys where you are. Maybe another thing to consider is a roof ridge vent tho its probably more economical when you are replacing your roof.
I'm coming in in the middle of the thread. I have an unfinished attic with no window, and a trap door between the attic and the second floor.
I love my electric roof fan. It took 10 degrees off my second floor, and the townhouse already had full width soffitt vents front and back and a full width ridge vent. I don't use AC at all normally, live in Baltimore, and when I bought the house the first summer, it was too hot to go upstairs at all after work. I would sleep in the basement and go upstairs in the morning to wash and get new clothes. After the fan the upstairs was usable to change clothes, watch tv or work at my desk, and sleep. A couple weeks a summer are still pretty hot.
The fan keeps the attic from ever gettting that hot. It goes on around 10 or 11 in the morning and turns off between 6 and 10PM, so it makes no noise when I'm trying to sleep.
There is so much circulation now that after 15 or 18 years I found a layer of "lint" on all of the soffitt vent screens, like one find on a clothes dryer screen but not nearly as heavy. None of my neighbors had that. I peeled it off.
It's possible I need more insulation in the attic "floor". The fiberglass only comes up to the top of the joists, and I thought that was enough. I have to get more info about that.
If you refer to an attic fan, some will think you mean what others call a whole house fan, a fan in the ceiling of the second floor, that only works when it has gotten sufficiently cool out side, and which some use while they are sleeping. Too much noise.
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