1. Run the attic fan at night, and it cools the house more rapidly and, more importantly, more thoroughly. It moves cool night air through the house and not only cools the interior but more effectively cools the structure of the house itself. Air in motion cools better than air which is not moving. That means the house stays cooler longer, without the fan, the next day because the structure itself serves as a "heat sink"

2. On days that it is warm and humid having the attic fan running will cause air to be in motion through the house and will cause it to feel significantly cooler. It is vastly less expensive than air conditioning and on many days will be sufficient to provide comfort. Humid air in motion can feel as much as ten degrees cooler than the same air which is not moving. Parameters are difficult to specify, but even fairly low humidity and quite high temperatures can be rendered quite comfortable by a whole house attic fan.

Not knowing your climate makes it difficult to say whether or not it would serve your purpose, but in San Diego it is quite adequate for all but a few days in summer.

I retired to the Midwest for affordability, and the climate here at 850' above sea level gives us the same gardening zone as southern Maine - 5B. I don't usually need even the whole house attic fan until mid-June or so, sometimes almost July. But every August it gets brutally hot and I'm forced to use the AC 24/7 for several weeks at least. I'd still be considering a powered attic ventilator IF and when I might be able to afford something with a convenient off switch for AC season.

But if I can't turn it off and must turn on the AC, it sounds as if the powered attic ventilator might actually cost me MORE $ then. That's the only time I'm concerned about and is the main focus of my question.

Rest assured I use every passive means possible before resorting to energy use. Not only did I have larger openings made at the soffits, the new heavy duty metal roof I had installed has a vent ridge too; or ridge vent, I'm not quite sure... Except I am certain that even a solar powered attic ventilator with a shut off for AC times will have to wait quite awhile longer before I can pony up the dough.

it not o come on untill say 90 degrees. I suspect the ones you are looking at come that way also

but I already have the whole house attic fan, and it took almost 2 years to find one to fit the super-narrow upstairs hallway. The only model in that size came with nothing more than a pull chain.

It's a solar attic ventilator (different thing) I want to add that had me concerned because of what I read in the trades; concern that it would have to be turned off during AC season and the fact that the only kind I could begin to afford just fits outside the soffit and doesn't require wiring, just mounting.

"But if I can't turn it off and must turn on the AC, it sounds as if the powered attic ventilator might actually cost me MORE $ then. That's the only time I'm concerned about and is the main focus of my question."

Of course you can turn it off. Any contractor who installed a whole house attic fan without providing a master control switch should be reported to the licensing board as incompetent. I would not even have a thermostat, because that is reactive, and a whole house fan should be used proactively. It should be run when the air is cool to cool off the structure of the house and then shut off when the outside air is hot. Once the house has heated up again, turn it back on to move the air. No computer or thermostat can do that for you, since you do it based on how the air feels.

When airconditioning season begins just leave it shut off, but using it will certainly shorten the length of time that you need to use air conditioning. Of course you do not use the fan when the air conditioner is in use, and it has automatic gravity-actuated shutters to prevent air flow when the fan is not running.

Don't let the contractor sell you any fancy, computerized control systems for it. All you need is an on/off switch and your own brain. A little experimentation and experience will teach you when to use the switch.

not the whole house attic fan. And unfortunately I cannot report a contractor because there was none for the whole house attic fan! It took me a couple years of (semi-excellent) searching to even find one that would fit the narrow upstairs hallway in this 100-yr-old house. (Funny; the rooms are all 15x15 or more but the stairway and upstairs hallway are narrow as cattle chutes! The single model whole house attic fan I found came ONLY with a pull chain. Well, at least it's more design compatible!

It's the prospect of adding a solar powered attic ventilator at the soffit and the warnings I read in the trades about how it would supposedly draw up refrigerated air during AC season and send the treated air back outside. But since first posting, I've thought about how well I can shut off the upstairs anyway, as I always do during extreme temps either way. The stairway can be closed off at the bottom AND top of the stairs. So I probably don't need to worry about a net financial loss in my situation when the AC runs down there. I don't use the upstairs at all when heating or cooling.

And since I can't afford the services of an electrician to install a solar attic ventilator with some kind of convenient downstairs kill switch, if indeed any such solar one exists, I'll have to take my chances with the simple kind that doesn't even require wiring, just someone nimble and crazy enough to climb up on the alpine roof.

I really appreciate people helping me think this through. I've learned the advisability of asking advice, because things are pointed out that never occurred to me. Thanks.

That advice is excellent. You should have an on/off switch, and you do not want to run it when you are running the a/c, ever. You are right, that would just pull all the cooled air from the house. Attic fans were used prior to having a/c in homes because they do cool the house down, but they are not meant to be used when a/c is used.

Edit: I don't think that it matters whether it runs with solar or not, as long as you are able to turn it off when needed---and a solar powered fan should not be a problem to turn off.

but I think just perhaps people are thinking the (possible) solar powered attic ventilator and the whole house attic fan I already have are one and the same, when they're 2 different items.

The whole-house attic fan I've had for 6 years took almost 2 years to find one to fit the super-narrow upstairs hallway. The only model in that size came with nothing more than a pull chain. Thank goodness it still has really strong pull.

It's a solar attic ventilator (different thing) I want to add that had me concerned because of what I read in the trades; concern that it would have to be turned off during AC season and the fact that the only kind I could begin to afford just fits outside the soffit and doesn't require wiring, just mounting. By the time I paid an electrician to install a fancier solar kind with a kill switch inside the house it would cost a minimum 3 times what the simple one that only requires mounting, no wiring at all. I can't afford that.

And of course I've never tried to run the whole house attic fan I already have at the same time as the AC.

I've since decided not to worry though because with all the mental stimulation everyone kindly offered, I realized I can still shut off the stairway at the bottom and top; since I don't use the upstairs during heating and cooling weather, I don't think the downstairs window AC will be bothered. Took me 2 years to find an 18K BTU AC narrow enough to fit any of the windows, too. In a 100-yr-old house they're tall and quite narrow just like the stairway and hallway. The only kind of regular window ac that would fit in these windows would be too wimpy to cool much more than a closet. You can imagine the vastly greater expense of a central AC system and all the new ductwork that would require. Not to mention the additional cost of operation.

That's part of the fun(?) of real Vics. Trying to find stuff that will fit. Couldn't be done w/o the internet. Doors are narrow too. The main compensating virtue is that the rooms are 15x15 at minimum. Well, except the upstairs bath, which is only 15x12. Everything in life's a trade off.

before AC.

We lived by the attic fan. That - and an elaborate ritual by my Mother.

When she got up in the morning, the windows and drapes on the east side of the house were shut. At midday-ish - all of the windows and drapes were shut. Around mid to late afternoon, the windows on the east side of the house were opened. At bedtime, all of the windows were opened.

The attic fan was used as people have stated above. We turned it on to move the air and to pull the hot air up and out of the house. It could also be used "in reverse" to pull air down INTO the house - but I'll be damned if I remember the formula for that scenario. That was a long time ago.

The only benefit I see to having a thermostat would be to having it run - when necessary - when you weren't home.

If you want an attic fan to help keep your house cool, there isn't enough insulation in the attic.

The primary purpose of attic fans is to keep the attic free of mold and mildew from moisture build up, and to keep the temperature from getting so hot that it reduces the life of your shingles. Moisture control has a big impact on how you do things like this, so you might want to familiarize yourself with the basics, starting in the crawlspace/basement and working your way up.

If your living space is heating up because the attic is hot, you might be more satisfied if you put down another 6 inches of insulation on the attic floor or covered what you have with reflective bubble wrap. Be sure the air flow from the eaves isn't obstructed and that there is sufficient flow out via something like ridge or gable vents. If there is a particular part of the attic that is getting moisture buildup because it is out of the general pattern of airflow, then something like the solar vent might be a good solution.

installed by Amish 6 years ago.

Good points you made. Do you think that under the circumstances I might be trying to gild the lily?

With all the variations - blackout curtains, shade etc - I'm comfortable enough until July before turning on even a table fan, then only the whole house attic fan until very late July maybe even August before needing any AC. Am I perhaps wishing to improve a system that's already at max? Had to install 21 new windows and made sure they were all very low E even though I couldn't afford double panes, needing that many at once. I do have smokey film on them. I just don't want to leave any available stone unturned.

If it were me, I'd probably want to define the insulation in terms of the R value in order to know what kind of performance it is delivering. If you think you need the attic fan to cool though, my guess is you think heat is radiating down; and it could well be even with insulation that is the maximum typically used since the level that constitutes "maximum" seems subjective.

It sounds like you've made a lot of effort to improve the efficiency of the home and I'm sure it's paying off big time for you. A ridge vent and gable vents should, if airflow from the eaves isn't obstructed, keep your attic dry.

Another thing to look at is the heat you are generating inside the house. One result of well sealed and insulated homes is that our activities produce heat, often a lot more than we realize. For insight into that and to see what real "max insulation" means from the energy side, google and investigate "net zero energy homes".

I think it is wonderful that you are digging into this and taking action. Good on you!

Magna seal soundproofing windows. They clip on to your regular window, inside of course. win.alturl.com Don't yet know how much they cost, but it looks like something I could do myself and certainly buy a few at a time. Soundproofing would also mean energy conservation, though both would be appreciated. This is basically a very quiet neighborhood with a lot of old houses and trees, but every little bit helps.

A neighbor sold to move to FL so of course she had a big yard sale, with a ton of magazines in the free box. Something like that I don't even look through at the moment; just scoop it up and carry it home for later examination. If I don't want all of it, I'll know someone who does. This time it turned out to be about 30 DIY publications, with valuable resource listings in the back. That's where I found the soundproof window ad.