Whole house fan info needed, keep or not?

[MediocreButArrogant]

They work amazingly well in our climate (southern part of Silicon Valley). It may hit mid to upper 80s during a typical summer day but cools off rapidly after the sun goes down. What a lot of people do is run the fan in the morning to fill their home with all that cool (low 60s) air. Then you can hold off to around 3-4PM before you have to run the air conditioner, if you have to run it at all. Then around 7PM or so you again open all the windows and suck in that 68F air and fill the house. They're most useful in a climate where it cools rapidly after sundown, and where excessive humidity isn't an issue.

We had a Quiet Cool 6400 installed this fall. With the automatic dampers flopped shut it's about R5. With an insulated insert it increases to R40. I haven't bothered adding any extra insulation, as we like to occasionally run it in the winter. The ancient fan it replaced had those aluminum louvers which were just a sieve for hot air in the winter. The new fan is also quiet enough that we can run it at night - on low we can't even hear it in the MBR.

[gentlearts]

I think the key determination is the amount of humidity where you live. If it is humid, you will run the AC. If it is warm enough, but not humid, you can run a fan to move the outside air in.

[Nayabone]

Originally Posted by blazerj

With central air, what's the benefit? I could see having an attic fan to remove the hot air in the summer, but won't a properly calibrated central air system move air just as efficiently?

The benefit over A/c is a whole house fan operates at a fraction of the cost of A/C.
I live in the So Calif where the summer time temperatures frequently exceed 105 degrees, with very little humidity, and the fan is a lifesaver. I turn the fan on for an hour after the sun goes down, and again early in the morning, at the coolest time of the day.
The ambient temperatures continue to cool off over night, with the coolest time of the day being 8am, at which time the temps begin to rise. I turn on my fan when I get up, usually around 6 am, and I can lower the indoor temps by 20 degrees in an hour or so. I crank on the timer and set it to go off at 8am and forget about it. With the indoor temps lowered that much, it takes the sun a lot longer to heat the house up.
It also lowers the attic temps dramatically, which means a cooler house during the daytime.
Only on the very hottest days do I ever turn on the A/C, and when it is necessary it is late afternoon. I turn it on for an hour or so and by that time evening is approaching and the temp is dropping.
I live in a 4000 sq ft, single story home with two central A/C units and have never had an electric bill exceed $100, mostly due to not using the A/C.
The fan is also nice in the winter when the inside temperature is cold (Calif desert cold, like 60's!). It warms up outside and I turn on the fan to suck some of the warm air inside, I can raise the indoor temps by 10 degrees, eliminating the need for the forced air heat. The automatic vents on the modern far seal tightly when closed so I have never noticed a problem with winter heat lose at the louvered vents.
Kitchen cooking odors, gone in 10 minutes with a flick of the switch..! A free benefit..
My whole house fan has paid for it's self many times over and I'm a true believer.

[kwong7]

I live in coastal Newport Beach with a north facing ranch-style house with central air. It can get pretty hot in the house during the summer when you don't want to run a 5.5kWh 20-year old AC compressor. I recently added a Quietcool WHF that quietly moves 1500 cfm of air off .104kWh. I regulate the fan based on the weather patterns (Yahoo! Weather app), and program my Belkin Wemo switch to schedule when the fan turns on and off throughout the day. We typically leave our awning windows open in the bathroom and bedrooms, so the WHF can suck up the hot air and draw in the cool air when my Nest thermostat and weather app indicate the crossover point. I love the whole house fan. It efficiently cools the house in the mornings and evenings, and I use it as a secondary ventilation hood when we do some serious cooking in the kitchen.

Lately, I'm considering adding an evaporative cooler to my house to try to efficiently cool it during the hot and dry days of summer.

[Nayabone]

Originally Posted by kwong7

I live in coastal Newport Beach with a north facing ranch-style house with central air. It can get pretty hot in the house during the summer when you don't want to run a 5.5kWh 20-year old AC compressor. I recently added a Quietcool WHF that quietly moves 1500 cfm of air off .104kWh. I regulate the fan based on the weather patterns (Yahoo! Weather app), and program my Belkin Wemo switch to schedule when the fan turns on and off throughout the day. We typically leave our awning windows open in the bathroom and bedrooms, so the WHF can suck up the hot air and draw in the cool air when my Nest thermostat and weather app indicate the crossover point. I love the whole house fan. It efficiently cools the house in the mornings and evenings, and I use it as a secondary ventilation hood when we do some serious cooking in the kitchen.

Lately, I'm considering adding an evaporative cooler to my house to try to efficiently cool it during the hot and dry days of summer.

We just installed a Bonaire Durango swamp cooler sold exclusively at Home Depot. So far M-I-L loves it. Look into one if your'e considering a swamp cooler.
Bonaire Durango 5,900 CFM 3-Speed Window Evaporative Cooler-6280035 - The Home Depot