On Jul 12, 12:12*pm, "Nonny" wrote:
"RickH" wrote in message

...





On Jul 10, 11:23 am, Lee B wrote:
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)?

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.

Nonny
--
On most days,
it's just not worth
the effort of chewing
through the restraints..- Hide quoted text -

- Show quoted text -

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.