Current house came with a whole house fan (not an attic fan, but the
kind in a hallway ceiling that sucks air into the attic). I was happy to
see that because I really liked the one in my old house. However the one
in the old house had a variable speed dial on it, and the new house's
fan has just one speed - high and loud with a simple off/on switch.
Is the variable speed a function of the fan itself or can that be added
at the switch? I'd definitely be having an electrician do it, but I'm
just trying to figure out if it's even doable, or if I'd end up needing
an entire new fan. And if so, would replacing an existing fan and switch
be difficult (ie cost me an arm and a leg)?
It sucks conditioned air from inside the house into the attic? Is it a
finished attic? Otherwise I can't see any logic in using this fan. Sounds
like the only speed setting you'd want on it is OFF.
But as far as speed control, it would depend on the type of the motor. It
is very likely a single phase AC, and so this controller Grainger sells
http://www.grainger.com/Grainger/items/5JJ60?Pid=search (it's only 2.5A
but cheap, and they have beefier models, too)
I guess, you'd need to get up there and see the motor first. Getting a
wrong speed controller will most likely kill either the motor or the
Whole house fans suck fresh air from outside through the open windows and
door and push it out the attic. On cool nights, it is a very efficient way
of cooling down the house. It does not replace AC on hot and humid days.
replying to JimT, FanOfWholeHouseFans wrote:
I beg to differ with "better than nothing." . Living in a dry climate where the
nights cool down very nicely, a whole house fan is the way to go for cooling
cheaply and sustainably in an overtaxed climate, and it works well. Shut
curtains and Windows all day to keep cool air in and hot air out. Then, once the
evening outside temp drops near or below the inside temp, we open every window
and switch on the whole house fan, which cools down the house lickety split with
fresh air. BUT, these things are loud and we could not sleep with it on or watch
tv or talK on the phone. So I too keep looking for a variable speed fan that we
can run quietly on low all night and when we need to hear. Would someone please
manufacture these. There are lots of us out here who hate AC and want to do
things more sustainably and who prefer exchanging stale house sir with fresh
air, and who live in places where cool night air in summer is the best way of
truly conditioning the ai!
On 07/15/2017 10:44 AM, FanOfWholeHouseFans wrote:
The "ideal state" is generous venting at the peak and soffits of your
roof. If the attic temp goes 5F above outdoor ambient, you need to add
more attic venting.
A hotter-than-ambient attic just needlessly raises your electric bill.
On Saturday, July 15, 2017 at 11:14:33 AM UTC-4, Jack wrote:
I guess you haven't seen many attics. Where did that 5F limit come from?
I have yet to see any attic where the attic temp in summer is just 5F
above ambient outside temp. Typical is more than several times that. Which is
what insulation is for. 5F is nuts and is never going to happen with
passive, even with fans it would require moving a lot of air when it's
85F+ and sunny.
There are many places where even with "excessive" ventiung the attic
will be WAY over 5 degrees over ambient. If I open the 6<2 foot gable
end door in the attic of my 15X15 foot shed and open the 6'6"x32" door
in the bottom, with a 3.3X3.3 foot opening between the main shed and
the attic, on an eveage summer day it will be over 10C hotter in the
attic, unless the breeze is coming from the south, blowing in the
attic door. The toof has a full length ridge vent and about 90 square
feet of fully open vented soffit
Seven years later you are still looking for a variable speed switch? I
put mine in 30 years ago. Works well.
On high, the fan sucks so much air it sucked my pet gerbil up and tossed
them around and finally spit them out the soffits.
On Sat, 15 Jul 2017 14:44:03 GMT, FanOfWholeHouseFans
We are in SW Florida and still benefit from whole house fans for about
half the year. I agree with Trader, even with two 22" fans running on
high, I never get the 1600 sq/ft attic below that mythical "5 degrees
above ambient" if the sun is shining.
As for variable speed, the best way is with multi speed motors.
You size the blade to the motor running on high and it will work OK at
the lower speeds. If the blade is not properly sized, you will burn up
the motor (too much pitch) or simply waste energy with it not moving
enough air (too little pitch).
The Grainger catalog has charts that will help you with this
One of my fans is 2 speed, one is 4 speed. (probably overkill since we
still only use two).
Some homes in SW Georgia (in the late 80's) had just a fan like the OP
mentions. It had just a light switch in the hall.
If you had very large shade trees and the Sun was right you opened a
window on the cool side of the house. Create a draft. In the kitchen,
close all windows and open the back door while cooking. It drafted the
heat into the hall fan and out the attic.
At night only open a BR window.
It also sucks non-conditioned air from the house and causes cooling
breezes, which is its main function.
You'd have to own one to know the benefits.
Before AC, fans were the only choice for comfortable air. They still
perform the same function.
It may be comfortable in the house without AC, but the sun has been
beating down on your roof all day, but if you have to go into the
unfinished attic to look for something stored away, the fan can replace
the hot attic air with outside air from open windows below the fan.
Burn something on the stove? The fan can remove the smoky air in the
house within a few minutes. You don't have to call the FD to aerate the
Still smell last night's fish dinner? Suck the smell out of the house.
Jasmine came in with the remnants of a meeting with a skunk? OK, you'll
have to run the fan a whole lot longer. (N.B.) Jasmine was my Golden
Retriever, and yes she did.
I have a WH fan and central AC and I use either of them at various times
of the year.
replying to DA, vertigo72480 wrote:
Whole house fans are designed to ventilate a home when the ambient temperatures
are nice enough to open the windows and doors. This facilitates air movement
with out needing to put box fans in windows.
It is a function of the motor, which will be a split-phase induction motor.
You either have a motor designed with multiple windings for multiple speeds,
or you don't. If you don't, the only practical way would be to replace the
motor with one designed with multiple windings, or get a new unit.
If you do have a motor designed with that feature, it will be a simple
manner of wiring up an appropriate switch to select between the speeds
On Sat, 10 Jul 2010 23:18:19 -0400, "Ed Pawlowski"
It's said that motors won't run off of light dimmers, but of the 6 or
so table fans I've used over the years, all but one worked fine. The
other one required a fan speed control, usually used for ceiling fans.
I got one at a surplus store.
I wouldnt' let the fan get so slow it stopped, althoughif the dimmer
is at the very bottom when this happens, maybe it's okay.. Depending
on the fan, it might well overheat if it did that, and burn out the
fuse (or worse?). Also if a whole house fan gets too slow, it won't
open the louvers I think, which are just sucked open.
*Induction* motors won't run off light dimmers. Universal motors will
(off dimmers rated for inductive loads). Small motors are almost
always universal motors. Whole house fans are likely a mix, with the
better ones being induction motors. Generally a belt is the tell
(belt => induction motor). I would guess the crossover is about
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