Whole house fan questions

[ivwshane]

I have a two story house that currently has single paned windows which I intend on replacing in time, however in the mean time my second story gets extremely hot during summer and even pretty warm during winter (I live in CA close to Sacramento). To help keep energy bills down and to get the house cooler quicker I was thinking about installing a whole house fan.


I have a couple of questions, first, would you guys recommend it (why and why not)?
Second, my biggest concern would be whether or not I have enough ventilation in the attic, I have a hip roof so creating an exhaust port seems like a tough job for the diy'er (meaning properly sealed, etc).

My house is about 1900sqft and the second story is 25'x31' (if it matters).

I'm currently looking at one of these two options:
http://www.atrendyhome.com/nequcowhhoat.html
http://www.wholehousefan.com/superfan.html

[jackellis]

I'd definitely recommend it for a couple of reasons. First, you can take advantage of cool evening air in summer rather than running your A/C. Use the whole house fan to cool the interior and the structure to as low a temperature as you can stand in the morning and it will take that much longer to heat up in the afternoon. Second, depending on how it's installed, a whole house fan will help evacuate hot air in the attic. What makes your house really hot is the 140 degree air trapped in your attic, not the 90 degree air outside.

I don't know which of the options you cited works best. We use window fans on the SF Bay peninsula but after just replacing a cedar shake roof with asphalt shingles that apparently increases the attic temperature, we may have to bite the bullet and but a whole house fan in.

[LinuxRandal]

Looking at the superfan one makes me wonder. It directly exits the attic, but what about the air in the attic itself? Wouldn't one be better off with an attic fan AND a gable fan, to draw air into the house, and completely through and out the attic?

[ivwshane]

Looking at the superfan one makes me wonder. It directly exits the attic, but what about the air in the attic itself? Wouldn't one be better off with an attic fan AND a gable fan, to draw air into the house, and completely through and out the attic?

For the super fan, when you have it vent directly out, one of the intake ports is left open in the attic to suck air out.

[mn95616]

I live in Davis (near Sacramento). My house is an older house with a very old AC unit. I replaced our windows with low-E dual pane windows. I have found that the whole house fan is just awesome! When it's not too hot, I don't run my AC and just run the house fan in the evening. On really hot day, I run the AC during the day, but the whole house fan at night. My energy bill dropped considerably.

Other things your may want to consider includes an attic fan and a turbine fan (either passive or solar). I installed a turbine fan over my garage as well.

Last - those whole house fans that you linked to are sure expensive. If you have a limited budget, I would go with a standard whole house fan (belt driven), two or three turbine fans, and an attic fan. You can also hire a professional to install additional vents in your eves.

Good luck.
Minh

[ivwshane]

Do you have a link to an example of a turbine fan?
My main concern with the "standard" house fan is noise.



Either way I still need a way to ventilate the attic better (using the easiest method possible).

mn95616 I'm in dixon and the recent whether is killing me

[aiyou]

I live in Sacramento, too, and have a number of co-workers that have installed the Quiet Cool system (http://www.atrendyhome.com/nequcowhhoat.html) and are quite happy with it. Significantly less noisy than the traditional whole house fan, and in reviewing installation instructions, don't appear too difficult. May need an electrician to run timer switches or additional power in the attic.

And, with a two-story house, the best place for a traditional whole house fan for me would be at the top of the stairs, right next to the intake for the heater/ac. Would probably be a very tight fit, may require joists to be cut, would be quite unsightly, and noisy next to the bedrooms

While I don't have them yet, the Quiet Cools are at the top of my list.

[mn95616]

Here is an example of a passive turbine vent. http://www.airvent.com/homeowner/pro...windTurb.shtml . I had three installed (2 over the house and 1 over the garage) for $370. If you have a composite roof - the installation of these fans are fairly easy. If you have a tile roof, then I would hire a professional. The turbine vents depends on both a slight breeze and convection to get it started. During the past couple of days, my turbine vents have been spinning like crazy (probably due to convection). You may also consider a solar powered version. http://www.airvent.com/homeowner/pro...olarRoof.shtml THey tend to be lower profile, and run even if there is no wind to get it started. The only thing is that they are expensive ($300ish). If you need a recommendation for an installer, PM me and I will send you a name of a place that my friend used. They also installed the eves vent for my friend. According to my friend, they were very professional and helpful.

You may also want to install a gable fan as well. I went the solar route for my gable fan because I didn't want to run new power line to my attic. There are disadvantage to solar powered gable fans though. 1) It only runs when the sun is out. Sometimes, I think it's still hot enough to continue to run when the sun is down, but the solar one just stops due to lack of sunlight. 2) I *think* the solar one has less CFM than the regular gable fan. http://www.nutonesales.com/attic.html

If you are going to hire someone to install a whole house fan - make sure that know what they are doing. When my friend had few people come out to give them estimate on installing a whole house fan, they did not even bother to calculate if there was enough opening in the attic. I have installed two direct drive whole house fan. In my house - the fan is relatively quiet (just a slight hum). On the other hand, the same fan in my parents house is quite noisy. I think the big difference is that at my home, I framed in the fan very well. The belt driven fans are much quieter - but requires a little more maintenance. Also - when purchasing the fan, make sure that you have enough CFM for your house. My friend has a two story house with a 1000 CFM unit. It moves so little air relative to his house size that it has become almost useless. He's getting ready to install a much bigger unit.

In all cases - make sure you have enough opening in your eves for proper air flow. Last - the three things I mentioned above are not mutually exclusive of each other. I have all three and it has made a huge difference. Right now - my whole house fan is on, and I am loving it!

[mn95616]

I just read your post, and you mentioned that you have a hip roof. I guess that means that a gable vent is out of the question. I would still consider installing two turbine fans over the living quarter of your house. As far as adding more "exhaust ports" - your turbine vents opening and eve vents will act as your exhaust port when the fan is on. Eve vents are easy to install, but on a two story house, it will be a little more expensive. For a turbine vent to work properly, you will need proper eve vents. BTW - when you have eve vents installed, don't use the circular ones. Use the rectangular vents since they have much bigger surface area. Also - don't paint the screen on the eve vents because it reduces air flow. If you must pain - spray paint it before installing. I would not use house paint at all.

PS - you may need soffit vents instead of eve vents installed.

[Uncle Cracker]

If you live where humidity is not a problem, the concept of pulling out your interior air through a fan system is a good one, as warm inside air is replaced by cooler outside air. In high humidity, however, this is not so great, because you are pulling the humidity into your home along with that outside air. The big thing about A/C is that it recirculates and de-humidifies the inside air, not only making it more comfortable, but helping with mildew and odor reduction. It still does help, however to have a fan vented attic to keep attic space cooler, but not such a big fan that it pulls air from the living space that you have paid to have cooled and dried by your A/C.

[Hellrazor]

Venting the attic air outside shouldn't have a negative impact on the rest of your house. The temps in the attic easily climb over 100F during the warmer months. Even if you vent 120F air and draw in 90F air.. it should help reduce the cooling costs.

[jcrenick]

A whole house fan is a good investment. I have one. It is an old direct drive model. I open the windows in the evenings run the fan at night then close the windows in the morning. Doing so allows me to keep the AC off when the evening temp drops below 70 deg. I would add that this one fan takes care of 4000+ sq ft of house.
As other posters have stated removing the hot air from your attic is critical. You must also check the venting in your attic to ensure you have proper venting otherwise you will pump hot air from your attic into your house.
My old fan is noisey but I do not hear it as I have it mounted in the attic. I set mine up in the attic access hole sitting on rubber mounts. I believe the belt drive fans are quieter. I can't see spending the money from the links provided when you can get a basic attic fan for under $200. Maybe I am cheap.

[atgcpaul]

I wanted to resurrect this post because I'd like to install one in my house.

Did the original poster ever install one? Which one? Noise is a concern but
the price seems to go up drastically as they get quieter.

Additionally, some of the belt driven ones, although less expensive, are roughly
3'x3'. Doesn't this involve cutting into the attic floor joists?

Thanks, Paul

[ivwshane]

No I never installed one because I didn't want to start tearing into my roof.

My sister in law has one in her house and it worked really well!. The sound was loud but not so loud that you would rather be hot than have it running.

One thing I noticed about her setup (which seemed to be something standard like you might get from home depot), is that it didn't need to be on for very long to do it's job. Her fan was powerful enough that when you hit the switch you feel a breeze pick up right away and within a minute or so you could turn it off.


I really should install one though, my downstairs is always cool and the upstairs gets pretty warm so I could see that it would benefit me pretty good.

[rfisher7381]

We installed an AirScape 1.7 last year. We had a belt drive style you can buy at Lowes or Home Depot and it worked but it was single speed and LOUD. This unit is two speed and very quiet. We usually use it on low speed and let it slowly cool the house from late evening until mid morning. Their web site is www.airscapefans.com. As you noted, adequate attic ventilation is critical.