Attic Fan (insurance, crawl space, heat pump)

[Green Man 7]

I found that attic fan works great for me. My 2nd floor is a lot cooler in summer (than when the fan broke). I did not check the electrical bill saving. But, the difference is between feeling comfortable v/s feeling too warm.

[azinspect]

Powered vents can cause the attic to go into negative pressure (suck air) which may significantly worsen the leaks present in ductwork and through the interior wall locations. It is a little known fact that powered attic vents can actually increase your utility costs. Contact me if you want more information on energy efficiency, it is a very complex subject with a lot of mis-information floating around. Also, each house is different and every occupant uses the home differently.

[1999corvette]

I am a HVAC tech, and I do not have one on my house if that tells you anything

Now, a whole house fan may be worth it, the kind that has lovers that open up and suck air up into your attic through the ceiling, open some windows and help evacuate heat from the house.

Of course, it would only work when it's not too hot out, kinda like a evaporative cooler (swamp cooler)

[azdr0710]

that last picture of the large louvers is very nearly what we had in the midwest....when it was nice out, but still warm inside, we'd open the windows and instantly cool off the house with the attic fan, much like the diagram of the house shown above....

however, I don't think it vented thru the attic, actually....it sucked air in thru the open windows and vented directly outside thru the roof.....

many of us don't have a swamp box, which would do nearly the same thing, but in reverse, of course....you obviously don't need to run the water pump when trying to use the swamp cooler like an attic fan....but I'd rather just suck the outside air in thru open windows and vent directly to the outside via a large fan in the ceiling, avoiding any "attic pressure" problem....

still don't know why this isn't common here....right now it's about 65 out and 73 in....sure would be nice right about now!

[Bummer]

Originally Posted by azdr0710

that last picture of the large louvers is very nearly what we had in the midwest....when it was nice out, but still warm inside, we'd open the windows and instantly cool off the house with the attic fan, much like the diagram of the house shown above....

however, I don't think it vented thru the attic, actually....it sucked air in thru the open windows and vented directly outside thru the roof.....

many of us don't have a swamp box, which would do nearly the same thing, but in reverse, of course....you obviously don't need to run the water pump when trying to use the swamp cooler like an attic fan....but I'd rather just suck the outside air in thru open windows and vent directly to the outside via a large fan in the ceiling, avoiding any "attic pressure" problem....

still don't know why this isn't common here....right now it's about 65 out and 73 in....sure would be nice right about now!

You've just endorsed the advantages of "dual cooling," azdr.

I would not consider owning a home in this area without both A/C and a Swamp Cooler.

[Zathras]

Originally Posted by 1999corvette

I am a HVAC tech, and I do not have one on my house if that tells you anything

Now, a whole house fan may be worth it, the kind that has lovers that open up and suck air up into your attic through the ceiling, open some windows and help evacuate heat from the house.

Of course, it would only work when it's not too hot out, kinda like a evaporative cooler (swamp cooler)

We had that exact thing in our previous house here in Ohio. It sucked the warm air out of the house and into the attic, pulling cool air in through the open windows. It worked fantastic.
It did sound like we had a jet in our attic though!

[gentlearts]

Originally Posted by 1999corvette

I am a HVAC tech, and I do not have one on my house if that tells you anything

Now, a whole house fan may be worth it, the kind that has lovers that open up and suck air up into your attic through the ceiling, open some windows and help evacuate heat from the house.

Of course, it would only work when it's not too hot out, kinda like a evaporative cooler (swamp cooler)

We just moved into a house with the office in the bonus room, which has a window air conditioner which really can't keep up. The attic adjacent to this room is poorly insulated and there are a few cracks in the ceiling where hot air seeps in.
Our plan is to insulate, fix the holes in the ceiling and install a couple of attic fans (one in each separate attic area). Why would you not advocate them in AZ? What would be a better solution?

[Juram]

Originally Posted by gentlearts

We just moved into a house with the office in the bonus room, which has a window air conditioner which really can't keep up. The attic adjacent to this room is poorly insulated and there are a few cracks in the ceiling where hot air seeps in.
Our plan is to insulate, fix the holes in the ceiling and install a couple of attic fans (one in each separate attic area). Why would you not advocate them in AZ? What would be a better solution?

Probably because he repairs A/C units for a living.



Solar attic fans work fine when properly installed. You've got a lot of two-guy-and-a-truck type operations all around installing this stuff without having any clue as to what they are doing. Proper installation does work well in keeping air circulating throughout the attic and reducing the burden on the A/C in general.


You're very smart for upgrading your insulation as the vast majority of homes here are woefully lacking in that aspect. It would also be worthwhile to get your ducts checked out and maybe even look into the possibility of radiant barrier installation which also works fantastically out in this area, just be sure to go with the thick, perforated, double-sided material and not the spray crap.


As far as the size of your attic, unless you've got a super sealed off firewall in your garage attic, one 10 watt solar attic fan will be able to provide satisfactory cooling for about a 2000-2400 sq ft sized home. You can get more if you want, but generally, for a smaller home, one is plenty.

[1999corvette]

Originally Posted by gentlearts

We just moved into a house with the office in the bonus room, which has a window air conditioner which really can't keep up. The attic adjacent to this room is poorly insulated and there are a few cracks in the ceiling where hot air seeps in.
Our plan is to insulate, fix the holes in the ceiling and install a couple of attic fans (one in each separate attic area). Why would you not advocate them in AZ? What would be a better solution?

From the ones I have seen here in AZ, a lot of the motors are burned up because it is hot enough in the attic to keep the motor running constantly, even when the thermostat (on the attic fan) turned up to not come on at, lets say 140, most of the year.

I would think you would be better off with good insulation.

Also, most houses if you look, have vent holes http://www.heritagerestorationaz.com/images/photos/images/image55.jpg (broken link)

And at least 2 gable vents, so they get a little draft of outside air to flow through the attic.

[1999corvette]

The solar attic fan might be a good choice, I have never seen one, most attic fans I see are this type http://www.savenrgvi.com/badfan.jpg (broken link)