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)?

"Lee B" wrote in message
...

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)?


You need a switch that will handle the motor size in question. I cannot
imagine running it on high all the time. I ru n mine ab out half speed
after the first two minutes or so.

"DA" wrote

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.

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.

"DA" wrote in message
oups.com...
responding to
http://www.homeownershub.com/mainten...ed-452575-.htm
DA wrote:

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.

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.


Only makes since in certain climates. Hawaii would be one. Areas near the
coast etc. They work basically the same as a evaporative cooler but without
the cooling pads. I've suggested it for people that have a very limited
budget and a place to draw cool air in. Better than nothing.

On Sat, 10 Jul 2010 17:07:06 +0000,
(DA) 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.

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.

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.

Lee B wrote:

Is the variable speed a function of the fan itself or can that be
added at the switch?

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
available.

Jon

"Jon Danniken" wrote

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.

Not quite true. Mine works with a simple dimmer switch of proper capacity.
Multiple windings not needed.

Jon Danniken wrote:
Lee B wrote:
Is the variable speed a function of the fan itself or can that be
added at the switch?

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
available.

Jon

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 $.

On Jul 10, 5:23*pm, 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)?

Your fan motor will be an induction motor because they are quiet and
cheap. The speed they run at is frequency dependent. It's possible
to make motors that have in effect two windings and hence two speeds.
There are mickey mouse devices that cut the voltage to make the motor
run slower but this causes heating effects in the motor it might not
be designed for.
There are also electronic inverters that rectify your alternating
current & then output any frequecy you like. So the motor can be run
at a wide range of speeds but they are fairly expensive.
If tthere are belts linking you fan and motor, you might consider
changing the pulley ratio. It's quite hard to determine what ratio
you would need.

Lee B wrote:

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.

Yes, an electrician will know in short order what type of motor is in your
unit.

Jon

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)?


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
estimate.



--
LSMFT

I haven't spoken to my wife in 18 months.
I don't like to interrupt her.

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.

"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..

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.

On Jul 12, 12:03*pm, RickH wrote:
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.

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.

"Nonny" wrote

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.

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.

keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.

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.

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)?

Hi,
Anything is possible. Like infinite speed control tied to the ambient
temp. Wonders of electronic engineering....

On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:

keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.

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.

They're a tad expensive for a fan. Have you ever seen one on a whole house
fan?

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)?


What is the voltage and amperage ratings of the motor? Here are some
speed controllers to choose from.

http://www.amazon.com/s?ie=UTF8&rh=n...ntrol&p age=1

Tony wrote:
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)?


My fan has a 2 speed motor. The 2 speeds are from separate windings -
each speed has a different number of poles in the motor.

You can easily control a "universal" motor - the type with brushes. Not
likely that is what is in the fan.

Three phase motors can be controlled by changing the frequency. No
possibility there is a 3 phase motor in the fan. The control would be
relatively expensive. I have never seen info, but I suspect the new
variable speed furnace motors are of this basically this type.

You could probably use a variable frequency control for a standard
induction motor, but if the speed falls to where the start switch in the
motor turns on you will probably burn out the motor. And probably
relatively expensive.

If you use a "phase angle" controller, like a light dimmer, you could
control the speed - the motor speed falls farther from the "rotating
field" speed. Has the same problem with start switches. I believe the
torque falls rapidly as the speed drops, but the power required for a
fan, if I remember right, is about the 4th power of the RPM.



What is the voltage and amperage ratings of the motor? Here are some
speed controllers to choose from.

http://www.amazon.com/s?ie=UTF8&rh=n...ntrol&p age=1

Briefly looking at the info for one of the speed controllers, it says it
is for shaded pole motors (which are used in clocks and my bathroom fan)
and permanent split capacitor motors, which is not likely what is
being used for the fan. Not obvious from what I saw that the 10A speed
control would work for a typical induction motor, which is probably what
powers the fan. These controls are probably "phase angle" controllers -
as above.

Outside of a 2 (or more speed) induction motor, I don't know how you
reliably control the speed of an induction motor that probably powers
the fan. How does the control work? How do you avoid problems with the
start switch?

--
bud--

On Sat, 10 Jul 2010 23:18:19 -0400, "Ed Pawlowski"
wrote:


"Jon Danniken" wrote

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.

Not quite true. Mine works with a simple dimmer switch of proper capacity.
Multiple windings not needed.

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.

On Jul 13, 1:04*pm, mm wrote:
On Sat, 10 Jul 2010 23:18:19 -0400, "Ed Pawlowski"

wrote:

"Jon Danniken" wrote

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.

Not quite true. *Mine works with a simple dimmer switch of proper capacity.
Multiple windings not needed.

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.

*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
1/4HP.

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.

On Sat, 10 Jul 2010 13:07:33 -0400, "Ed Pawlowski"
wrote:


"Lee B" wrote in message
...

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)?


You need a switch that will handle the motor size in question. I cannot
imagine running it on high all the time. I ru n mine ab out half speed
after the first two minutes or so.

Originally they only came with one speed. Yes, I thought it was too
loud on high, especially since it was right outside my open bedroom
door.

On Tue, 13 Jul 2010 11:46:11 -0700 (PDT), keith
wrote:

On Jul 13, 1:04*pm, mm wrote:
On Sat, 10 Jul 2010 23:18:19 -0400, "Ed Pawlowski"

wrote:

"Jon Danniken" wrote

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.

Not quite true. *Mine works with a simple dimmer switch of proper capacity.
Multiple windings not needed.

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.

*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
1/4HP.

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
enough?

He could use teh toggle swtich for any old thing, including perhaps
turning off the fan without changing the speed setting.

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.

On Tue, 13 Jul 2010 21:00:40 -0400, mm wrote:

On Tue, 13 Jul 2010 11:46:11 -0700 (PDT), keith
wrote:

On Jul 13, 1:04*pm, mm wrote:
On Sat, 10 Jul 2010 23:18:19 -0400, "Ed Pawlowski"

wrote:

"Jon Danniken" wrote

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.

Not quite true. *Mine works with a simple dimmer switch of proper capacity.
Multiple windings not needed.

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.

*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
1/4HP.

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
enough?

You're not listening. Whole house fans often (if not usually) use induction
motors. These motor controllers WILL NOT work with induction motors. You'll
likely burn up both.

He could use teh toggle swtich for any old thing, including perhaps
turning off the fan without changing the speed setting.

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.

bud-- wrote:
Tony wrote:
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)?


My fan has a 2 speed motor. The 2 speeds are from separate windings -
each speed has a different number of poles in the motor.

You can easily control a "universal" motor - the type with brushes. Not
likely that is what is in the fan.

Three phase motors can be controlled by changing the frequency. No
possibility there is a 3 phase motor in the fan. The control would be
relatively expensive. I have never seen info, but I suspect the new
variable speed furnace motors are of this basically this type.

You could probably use a variable frequency control for a standard
induction motor, but if the speed falls to where the start switch in the
motor turns on you will probably burn out the motor. And probably
relatively expensive.

If you use a "phase angle" controller, like a light dimmer, you could
control the speed - the motor speed falls farther from the "rotating
field" speed. Has the same problem with start switches. I believe the
torque falls rapidly as the speed drops, but the power required for a
fan, if I remember right, is about the 4th power of the RPM.



What is the voltage and amperage ratings of the motor? Here are some
speed controllers to choose from.

http://www.amazon.com/s?ie=UTF8&rh=n...ntrol&p age=1


Briefly looking at the info for one of the speed controllers, it says it
is for shaded pole motors (which are used in clocks and my bathroom fan)
and permanent split capacitor motors, which is not likely what is being
used for the fan. Not obvious from what I saw that the 10A speed control
would work for a typical induction motor, which is probably what powers
the fan. These controls are probably "phase angle" controllers - as above.

Outside of a 2 (or more speed) induction motor, I don't know how you
reliably control the speed of an induction motor that probably powers
the fan. How does the control work? How do you avoid problems with the
start switch?

Uh... hello? A shaded pole motor IS an induction motor. Motor speed
controllers will vary their speed by varying the frequency. Try google.

http://www.google.com/search?num=50&...=&oq=&gs_rfai=

zzzzzzzzzz wrote:
On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:

keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.
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.

They're a tad expensive for a fan. Have you ever seen one on a whole house
fan?

http://www.amazon.com/s?ie=UTF8&rh=n...ntrol&p age=1

On Jul 14, 12:58*am, Tony wrote:
wrote:
On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:

keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.
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.

They're a tad expensive for a fan. *Have you ever seen one on a whole house
fan?

http://www.amazon.com/s?ie=UTF8&rh=n...Speed%20Contro....

Those are simple "dimmer" style controls. They are *not* for
induction motors.

Tony wrote:
bud-- wrote:
Tony wrote:
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)?


My fan has a 2 speed motor. The 2 speeds are from separate windings -
each speed has a different number of poles in the motor.

You can easily control a "universal" motor - the type with brushes.
Not likely that is what is in the fan.

Three phase motors can be controlled by changing the frequency. No
possibility there is a 3 phase motor in the fan. The control would be
relatively expensive. I have never seen info, but I suspect the new
variable speed furnace motors are of this basically this type.

You could probably use a variable frequency control for a standard
induction motor, but if the speed falls to where the start switch in
the motor turns on you will probably burn out the motor. And probably
relatively expensive.

If you use a "phase angle" controller, like a light dimmer, you could
control the speed - the motor speed falls farther from the "rotating
field" speed. Has the same problem with start switches. I believe the
torque falls rapidly as the speed drops, but the power required for a
fan, if I remember right, is about the 4th power of the RPM.



What is the voltage and amperage ratings of the motor? Here are some
speed controllers to choose from.

http://www.amazon.com/s?ie=UTF8&rh=n...ntrol&p age=1



Briefly looking at the info for one of the speed controllers, it says
it is for shaded pole motors (which are used in clocks and my bathroom
fan) and permanent split capacitor motors, which is not likely what
is being used for the fan. Not obvious from what I saw that the 10A
speed control would work for a typical induction motor, which is
probably what powers the fan. These controls are probably "phase
angle" controllers - as above.

Outside of a 2 (or more speed) induction motor, I don't know how you
reliably control the speed of an induction motor that probably powers
the fan. How does the control work? How do you avoid problems with the
start switch?

Uh... hello? A shaded pole motor IS an induction motor. Motor speed
controllers will vary their speed by varying the frequency. Try google.

http://www.google.com/search?num=50&...=&oq=&gs_rfai=


You will not find a shaded pole motor on a fan of any size - like a
"whole house" fan that makes too much noise.

The motor controller I commented on (from your previous post) is almost
certainly a "phase angle" control (like a light dimmer). It does not
change the frequency.

The controller I looked at was also stated to work with a permanent
split capacitor motor. If I remember right, they are a 2 winding motor
with a capacitor in series with one of the windings. There is no start
cap and no start switch. It is basically a 2-phase motor. (I don't
remember ever seeing one.)

Neither of the motors that the controller said it was good for has a
start switch. A "whole house" fan will almost certainly have an
induction motor with a start switch. Using a dimmer-type control, as
above, can easily burn out the motor. It is a misapplication according
to the limited information provided with the control.

--
bud--

keith wrote:
On Jul 14, 12:58 am, Tony wrote:
wrote:
On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:
keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.
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.
They're a tad expensive for a fan. Have you ever seen one on a whole house
fan?
http://www.amazon.com/s?ie=UTF8&rh=n...Speed%20Contro...

Those are simple "dimmer" style controls. They are *not* for
induction motors.

http://www.kbelectronics.com/kbsearc..._kbwc_115k.htm
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
see it!

bud-- wrote:
Tony wrote:
bud-- wrote:
Tony wrote:
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)?


My fan has a 2 speed motor. The 2 speeds are from separate windings -
each speed has a different number of poles in the motor.

You can easily control a "universal" motor - the type with brushes.
Not likely that is what is in the fan.

Three phase motors can be controlled by changing the frequency. No
possibility there is a 3 phase motor in the fan. The control would be
relatively expensive. I have never seen info, but I suspect the new
variable speed furnace motors are of this basically this type.

You could probably use a variable frequency control for a standard
induction motor, but if the speed falls to where the start switch in
the motor turns on you will probably burn out the motor. And probably
relatively expensive.

If you use a "phase angle" controller, like a light dimmer, you could
control the speed - the motor speed falls farther from the "rotating
field" speed. Has the same problem with start switches. I believe the
torque falls rapidly as the speed drops, but the power required for a
fan, if I remember right, is about the 4th power of the RPM.



What is the voltage and amperage ratings of the motor? Here are
some speed controllers to choose from.

http://www.amazon.com/s?ie=UTF8&rh=n...ntrol&p age=1




Briefly looking at the info for one of the speed controllers, it says
it is for shaded pole motors (which are used in clocks and my
bathroom fan) and permanent split capacitor motors, which is not
likely what is being used for the fan. Not obvious from what I saw
that the 10A speed control would work for a typical induction motor,
which is probably what powers the fan. These controls are probably
"phase angle" controllers - as above.

Outside of a 2 (or more speed) induction motor, I don't know how you
reliably control the speed of an induction motor that probably powers
the fan. How does the control work? How do you avoid problems with
the start switch?

Uh... hello? A shaded pole motor IS an induction motor. Motor speed
controllers will vary their speed by varying the frequency. Try google.

http://www.google.com/search?num=50&...=&oq=&gs_rfai=


You will not find a shaded pole motor on a fan of any size - like a
"whole house" fan that makes too much noise.

The motor controller I commented on (from your previous post) is almost
certainly a "phase angle" control (like a light dimmer). It does not
change the frequency.


What is it like to guess instead of going by the facts? Probably
everything goes your way, if you don't read the specs.



The controller I looked at was also stated to work with a permanent
split capacitor motor. If I remember right, they are a 2 winding motor
with a capacitor in series with one of the windings. There is no start
cap and no start switch. It is basically a 2-phase motor. (I don't
remember ever seeing one.)

Neither of the motors that the controller said it was good for has a
start switch. A "whole house" fan will almost certainly have an
induction motor with a start switch. Using a dimmer-type control, as
above, can easily burn out the motor. It is a misapplication according
to the limited information provided with the control.

There is a lot more info out there. I can't do all the work for you,
look up KB Electronics and read the specs. And if you look at the
picture, you will see that from the "off" position,the first "on"
position is "high". Yes it will start the motor.

JIMMIE wrote:
On Jul 10, 12:23 pm, 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)?

The fan in my house was single speed. About the only thing it was
practical for was evacuating smoke when my wife burned dinner. I had
to replace the motor to get it to operate at lower speeds. Now its 3
speed and I stilll wish it had a slower speed. I am considering
mounting some muffin fans in the corners of the chassis for when I
want to draw a gentle flow into the house.

Jimmie

Is it belt driven? How about a smaller drive pulley?

"Tony" wrote in message
...
bud-- wrote:
Tony wrote:
bud-- wrote:
Tony wrote:
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)?


My fan has a 2 speed motor. The 2 speeds are from separate windings -
each speed has a different number of poles in the motor.

You can easily control a "universal" motor - the type with brushes. Not
likely that is what is in the fan.

Three phase motors can be controlled by changing the frequency. No
possibility there is a 3 phase motor in the fan. The control would be
relatively expensive. I have never seen info, but I suspect the new
variable speed furnace motors are of this basically this type.

You could probably use a variable frequency control for a standard
induction motor, but if the speed falls to where the start switch in
the motor turns on you will probably burn out the motor. And probably
relatively expensive.

If you use a "phase angle" controller, like a light dimmer, you could
control the speed - the motor speed falls farther from the "rotating
field" speed. Has the same problem with start switches. I believe the
torque falls rapidly as the speed drops, but the power required for a
fan, if I remember right, is about the 4th power of the RPM.



What is the voltage and amperage ratings of the motor? Here are some
speed controllers to choose from.

http://www.amazon.com/s?ie=UTF8&rh=n...ntrol&p age=1




Briefly looking at the info for one of the speed controllers, it says
it is for shaded pole motors (which are used in clocks and my bathroom
fan) and permanent split capacitor motors, which is not likely what is
being used for the fan. Not obvious from what I saw that the 10A speed
control would work for a typical induction motor, which is probably
what powers the fan. These controls are probably "phase angle"
controllers - as above.

Outside of a 2 (or more speed) induction motor, I don't know how you
reliably control the speed of an induction motor that probably powers
the fan. How does the control work? How do you avoid problems with the
start switch?

Uh... hello? A shaded pole motor IS an induction motor. Motor speed
controllers will vary their speed by varying the frequency. Try google.

http://www.google.com/search?num=50&...=&oq=&gs_rfai=

You will not find a shaded pole motor on a fan of any size - like a
"whole house" fan that makes too much noise.

The motor controller I commented on (from your previous post) is almost
certainly a "phase angle" control (like a light dimmer). It does not
change the frequency.


What is it like to guess instead of going by the facts? Probably
everything goes your way, if you don't read the specs.



LOL....Always worked for me.

On Jul 12, 11:20*pm, "
wrote:
On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:
keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.

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.

They're a tad expensive for a fan. *Have you ever seen one on a whole house
fan?- Hide quoted text -

- Show quoted text -

$39 is not too bad I dont think, I use the 10 amp one at the bottom of
this page (my fan only draws 5 amps but I wanted the controller to run
real cool so I oversized it): I got this same model for about $25
elsewhere.

http://www.electricmotorwarehouse.com/kbwc.htm

On Jul 13, 12:11*pm, bud-- wrote:
Tony wrote:
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)?

My fan has a 2 speed motor. The 2 speeds are from separate windings -
each speed has a different number of poles in the motor.

You can easily control a "universal" motor - the type with brushes. Not
likely that is what is in the fan.

Three phase motors can be controlled by changing the frequency. No
possibility there is a 3 phase motor in the fan. The control would be
relatively expensive. I have never seen info, but I suspect the new
variable speed furnace motors are of this basically this type.

You could probably use a variable frequency control for a standard
induction motor, but if the speed falls to where the start switch in the
motor turns on you will probably burn out the motor. And probably
relatively expensive.

If you use a "phase angle" controller, like a light dimmer, you could
control the speed - the motor speed falls farther from the "rotating
field" speed. Has the same problem with start switches. I believe the
torque falls rapidly as the speed drops, but the power required for a
fan, if I remember right, is about the 4th power of the RPM.



What is the voltage and amperage ratings of the motor? *Here are some
speed controllers to choose from.

http://www.amazon.com/s?ie=UTF8&rh=n...20Contro... *

Briefly looking at the info for one of the speed controllers, it says it
is for shaded pole motors (which are used in clocks and my bathroom fan)
* and permanent split capacitor motors, which is not likely what is
being used for the fan. Not obvious from what I saw that the 10A speed
control would work for a typical induction motor, which is probably what
powers the fan. These controls are probably "phase angle" controllers -
as above.

Outside of a 2 (or more speed) induction motor, I don't know how you
reliably control the speed of an induction motor that probably powers
the fan. How does the control work? How do you avoid problems with the
start switch?

--
bud--


Mine works great, the KB controller I got hooks up in series, I capped
the low speed wire on the motor and just use the high speed one.

On Jul 14, 1:58*pm, Tony wrote:
keith wrote:
On Jul 14, 12:58 am, Tony wrote:
wrote:
On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:
keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.
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.
They're a tad expensive for a fan. *Have you ever seen one on a whole house
fan?
http://www.amazon.com/s?ie=UTF8&rh=n...Speed%20Contro...

Those are simple "dimmer" style controls. *They are *not* for
induction motors.

http://www.kbelectronics.com/kbsearc..._kbwc_115k.htm
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
see it!- Hide quoted text -

- Show quoted text -


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).

http://www.kbelectronics.com/kbsearc...kbwc_110kb.htm

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.

On Jul 14, 1:58*pm, Tony wrote:
keith wrote:
On Jul 14, 12:58 am, Tony wrote:
wrote:
On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:
keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.
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.
They're a tad expensive for a fan. *Have you ever seen one on a whole house
fan?
http://www.amazon.com/s?ie=UTF8&rh=n...Speed%20Contro...

Those are simple "dimmer" style controls. *They are *not* for
induction motors.

http://www.kbelectronics.com/kbsearc..._kbwc_115k.htm
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
see it!

You won't find a whole house fan that uses a shaded pole motor, but go
ahead and smoke your fan.

On Wed, 14 Jul 2010 12:28:36 -0700 (PDT), RickH
wrote:

On Jul 12, 11:20*pm, "
wrote:
On Mon, 12 Jul 2010 23:23:02 -0400, Tony wrote:
keith wrote:
On Jul 12, 12:03 pm, RickH wrote:
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.

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.

They're a tad expensive for a fan. *Have you ever seen one on a whole house
fan?- Hide quoted text -

- Show quoted text -

$39 is not too bad I dont think, I use the 10 amp one at the bottom of
this page (my fan only draws 5 amps but I wanted the controller to run
real cool so I oversized it): I got this same model for about $25
elsewhere.

http://www.electricmotorwarehouse.com/kbwc.htm

That's a "dimmer" style controller. Do *not* use that for an induction motor.
Induction motors need a VFD type controller, which is far more expensive.

keith wrote:
On Jul 14, 1:58 pm, Tony wrote:
keith wrote:
http://www.amazon.com/s?ie=UTF8&rh=n...Speed%20Contro...
Those are simple "dimmer" style controls. They are *not* for
induction motors.
http://www.kbelectronics.com/kbsearc..._kbwc_115k.htm
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
see it!

You won't find a whole house fan that uses a shaded pole motor, but go
ahead and smoke your fan.

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
really.