And of course, back to the oP's question, they sell fan speed controls
that mount like wall switches. Often there's a switch there for the
light that often comes with a ceiling fan. I presume whole-house fans
use more current than ceiling fans, but would the speed control be big
He could use teh toggle swtich for any old thing, including perhaps
turning off the fan without changing the speed setting.
Thanks. Is that something an electrician could tell by looking at the
unit? (No point in telling me what to look for, I'm not built for
climbing a ladder up into that little trap door to the attic... or worse
trying to climb back down!). I got the old fan at Sears and also got the
variable speed dial there. I can't remember what I paid for that fan 20+
yr ago, but I know it wasn't a top of the line or anything special. I
sort of assumed they all worked the same and was surprised when I
encountered this one.
I can't use the fan too often, living in the mid-Atlantic where it's
often too humid to suck that wet air in. But we've had a few really
pleasant evenings where the humidity was low, and it would be nice to
turn off the A/C and feel like I'm saving $.
Yes, it's doable. There are variable AC motor controllers. They are not
cheap. Might be cheaper to replace the motor with a 3 speed wound rotor
motor or a DC motor with speed controller. Electrician can give you an
Whole house fans are great. Yes you can put on a variable speed
controol, but I suggest you over-rate the control amperage you buy by
double. For example if the fan draws 5 amps then get a 10 amp
control. Also when turning it on make sure the control passes through
the higher speed, then you lower it. This is so the motor gets enough
starting current. I replaced the Off/High/Low switch on mine with a
variable speed. You only use the High speed motor input wire, just
cap the low speed wire.
While a full variable speed controller would be nice, I wonder if
it really adds that much to the benefit of the fan. For instance,
the louvers of the fans require a minimum amount of pressure
differential for the air to open them, eliminating the lowest
speeds you could get with the controller. The one I installed in
our first house had a 2-speed switch for High/Low operation and we
seldom used it in any position other than High. Our second house
had two of the fans and again, both were left on High.
If the OP investigates and finds that his fan is a 2-speed one, my
suggestion would be to invest first in a DP switch and use the
high/low speeds to see if it's worth the added cost of buying a
full controller for anything intermediate or lower.
I needed a speed adjustor because sometimes you choose to not open
enough widows to keep up with the fan draw, so a nice slow fan is nice
if you just want one bedroom window open at night. Even on low, may
fan was overdrawing most of the time, its a 30 inch belt drive.
Also depending on how much output venting the user has in their roof
and eves, a variable speed lets you not overload the amount of air
your attic is capable of evacuating. Its cheaper than installing more
vents. Also the variable speed saves kilowatts. The louver spring
can be easily adjusted to require only a very light amount of air to
open them, mine pops open very easily.
I always start my fan on high for a couple of minutes to get the air
flowing. Then I can turn it to the lowest setting and it works just fine.
I like the variable speed and set it according to the needs at the moment.
That depends on the motor. If it's a universal motor it'll probably
work fine. If it's an induction motor, probably not. Induction
motors tend to be "constant RPM" or with a given load, "constant
power" devices. As the voltage is reduced they'll want to maintain
RPM, which requires the same power, thus current increases.
If the fan is belt driven it's probably an induction motor.
If you use an AC motor speed controller it will work fine. It does not
control speed with changes in voltage, it changes speed with changes in
the frequency. This type of speed control also lets the fan run at
lower speeds without stalling. The days of the old rheostats are long gone.
It says Shaded Pole motors, which ARE induction motors. Unless you can
show me a shaded pole motor that is not an induction motor? I'd love to
Yes, below is the model I am using with the 30 inch belt drive WHF
currently being sold by Home Depot (I think its called Master Flow).
Works great but I did want to inform the family to start it on high
before turning it lower, but even if they did spin the knob to low
from off quickly the motor still starts ok. The off click goes
straight to High, turning the knob clockwise keeps getting lower,
which is the proper configuration for a motor speed control.
Light dimmers are bad because they force the motor to start on Low and
you must quickly crank the knob to get to High. Having the
potentiameter go from Off click to High to Low as you move clockwise
is the proper configuration for a fan control.
I said those dimmers were indeed for shaded pole motors, someone
disagreed, I don't really care who it was. But the fact is that the
speed controls I suggested can be used on shaded pole motors.
Hell, I don't even have a whole house fan, so I don't suppose there is
much chance of me smoking my fan. Unless it was made of hemp. No not
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