We went to a friend's house for dinner last night and they demonstrated their whole house fan to us. Very impressive. One of the issues we come across in our house is that when we open up the front windows and back windows, we don't get much of a draft through the house. We get better results if the front door is open, but without a screen on it, we get a lot of June bugs (now July bugs) and crane flies for our troubles. The house fan did a fantastic job of "pulling in" the cooler outside air to cool down a stuffy room (picture a room, if you will, with 2x boys around 12 years old, with the windows closed on a 80+ degree day playing video games for a couple of hours). The fan cooled down that room in less than a couple of minutes (woo hoo!). Anyhow, I was curious who has these, how well they work, cost including installation etc. It may be a future purchase for us.
We have three in our building, each cooling a different section. They work great in areas that cool down at night. Cost is minimal. Installation involves making a opening in the ceiling between the joists and running the wiring. Your attic space needs to have adequate ventilation, but then again, if it doesn't you have more problems than just a hot house. I highly recommend whole house fans. Tom
Only drawback of a whole house fan is in the wintertime, you need to insulate over the fan and seal it from drafts to keep the heat in, other than that, they work great. I have one in my barn to keep it cool.
I grew up in a house with a whole house fan and the house I bought had one too so I can't give you info on cost or installation, but I don't think it's a huge project (as described above). I love it. I run it in the early evening when the temp has dropped or before bed. It cools the 2nd floor down and makes sleeping much more comfortable. I only use the central AC when it's hot & humid. I'm in a cold zone so in the winter you can either (a) get a box style hood to go over it in the attic or (b) put some insulation up over the louvers. I got a roll of insulating foam, cut it to size, and put up velcro around the outside frame. It's easy press into place in the winter and simple to take down in the summer. The velcro color matches the frame and the foam is the color of the ceiling so I don't really notice it.
I've got our whole house fan blocked off with foamular insulation. It really wasn't installed in a useful location (not high enough in the structure--instead pulling from the main level). I experimented with it a few times last year and concluded it wasn't worth much. Our layout is a 3-2 split so the best way to get circulation is to leave the highest level door open, then open the upper window sections (double hung windows) on this level, and open the lower halves of windows in levels below. This creates a pretty strong natural draft (chimney effect). I leave the large basement area closed until temps. fall into the mid/low 60's, because that level tends to run in the very low 70's anyway. The trick for us is judging the balance of humidity and temp that makes window ventilation work. Even though I run the main level at 81 F, it doesn't make sense to open the windows there and above until the air temp is less than 72 F (roughly the AC balance point for the home.) Humidity level at 72 F in the evening is around 80%, so it is more comfortable to leave the home in the 45% range and buckled up. But when it breaks 70 F and looks like it will bottom below 67 F, the humidity penalty is worth paying. I button things up tight in the morning before ambient temps get much above 70 F. When I can drop the main level temps into the mid 70's overnight, the AC won't kick back on until about 3-4 PM on a 90+ degree day (by which time the internal humidity is nudging 60%.)
