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"Attic Fan" in common parlance but more correctly a whole house ventilator fan. Sucks air out of the house and exhausts inside the attic which should have adequate vents to outdoors.

BIG chance of backdrafting of gas appliances and chimneys when in operation.

Occupants must open windows to get flow through ventilation. Very useful in hot climates that cool down at night.

They were very common here before a/c became popular.

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Yeah, back-drafting gas appliances can be a problem in certain circumstances. Here's how I tell my clients to use them.

Come home and let's assume it's 80 degrees+ in the house. Rather than turn on the ac, run the fan for five minutes to suck out a lot of heat. Then, use the ac to more effectively/efficiently cool-down a now not-as-hot house.

'Course, since you don't see 'em much, you probably won't have to remember any of this. Your time could be better spent reading some really old and cool Audel's Builders books. . . (Shameless)

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I love the shameless plug you gave yourself Jerry. And btw, very cool books. My wife thought I was being a smart ass with her when she looked at the one with the proper manners and recipe's;) Anyway, this big ole ceiling fan just caught me off guard as I can't remember the last one I have seen installed here. Thanks for the information.

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I know a certain dumbass who turned one of those things on once, decided it was functional, and went about his business.

Ten minutes later, this same dumbass walked into the living room of the house he was in, and was dismayed to see soot and ashes covering the furniture--and still dancing in the air a little--along with pretty much everything else in the room.

Dumbass then realized that the fireplace damper was open when he switched on the whole-house ventilation fan, and that the contents of the firebox were sucked into the living room.

Dumbass learned a very important lesson that day.

Signed,

Dumbass

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We have lots of whole house fans. They work well because we get hot during the day and cool off at night. I ran my air conditioner only 1 day last summer.

As others have said, you have to open windows for them to work. You need sufficient attic ventilation in order to blow the air out of the attic without pressurizing it. Also, they're energy hogs in the winter because they have no insulation and leak air like a sieve.

Dear Dumbass, thanks for enlightening me about another of pitfall of whole house fans. I always appreciate learning at someone else's expense.

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A seller decided to demonstrate her whole-house fan to the buyer during my inspection. It was mid-winter with the house closed up tightly. The old giant oil-fired boiler exhaust got sucked right out of the draft-control damper will I was quite near. I felt almost like I might loose consciousness and had a terrible headache for hours.

"TURN IT OFF...TURN IT OFF...TURN IT OFF".... thud.

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I got one in my house. They are great in certain circumstances such as a cool evening to bring outside air in the open windows. The low setting is not too loud.

One drawback is the breach in the insulation qualities of the attic. This drawback can be made worse since these things are sometimes installed in the same hallway where a thermostat is located.

I addressed this in my house by building a box with a trap door over the fan unit in the attic. I then insulated the box and trap door. Additionally, I installed a cutoff switch in the attic next to the trap door. When ever the trap door is closed, the cutoff switch in the attic prevents you from turning the fan on in from the wall switch located in the hallway.

I'd say the trap door stays closed at least 85% of the year. There's only limited situations where it's beneficial to use these things in my area. If it's not hot or cold, it's humidity we're trying to manage. There's only a few weeks across spring or fall months where it's worth using it.

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BTW, whenever you see one of these, check for bottom cord of trusses being cut. Nine times out of ten, that's what happens when they're installed.

As I understand, no part of an engineered truss should be cut without an engineered plan of modification.

My house is stick built so I get a pass, right?

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The house I grew up in had one. Windows were generally open throughout the house before you turned it on. Our's was installed in the laundry room ceiling and we all cramped there together after lunch on hot summer days to nap. Coolest room in the house and the rhythm of the blades helped put us young uns to sleep. That was before AC was affordable.

Marc

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Jeez Rob,

I had a house with one of those off of Novelty Hill Rd. in Redmond yesterday. Bank owned - pre-offer. First one I'd seen in years. Maybe you and I did the same house. If not, it's a weird coincidence.

ONE TEAM - ONE FIGHT!!!

Mike

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