Fan Speed Adjustable?

Devil505 · Post by **Devil505** » Tue. Nov. 18, 2008 4:52 pm

I want to be able to control the fan speed of this unit I installed http://www.tjernlund.com/Tjernlund_Aireshare_Lit_8500730.pdf

http://www.tjernlund.com/airshare_ventilation.htm

But I don't know if the fan motor can be varied or what I would need to do it. (rheostat/??)
I wrote to the company but have not heard back. Any way to look at the specs to see what I would need?
Thanks

Highlander · Post by **Highlander** » Tue. Nov. 18, 2008 5:35 pm

Yes, that can be controlled, I would suggest one of the variable speed controllers sold in the big box stores for paddle or ceiling fans. Here is a link http://www.hardwarestore.com/rotary-fan-control-s ... 39053.aspx

Its rated at 5 amps, which should be plenty for that small blower motor.

Devil505 · Post by **Devil505** » Tue. Nov. 18, 2008 5:48 pm

Highlander wrote:Yes, that can be controlled,

Great!!

I'm not gonna let you off that easy though!

Is there such a thing as a variable speed control that also has a programmable timer in it? (I want to be able to have the fan turn on/off by the timer as well as be able to vary the speed)

Too much to ask?

Edit: I suppose I could use separate devices in series, eh?

WNY · Post by **WNY** » Tue. Nov. 18, 2008 7:19 pm

Yup, just plug the rheostat into the timer...

Devil505 · Post by **Devil505** » Tue. Nov. 18, 2008 10:23 pm

Done!! I bought a $12.00 , 3 speed fan switch & wired it into the fan power wire b4 it plugs into the timer. (doesn't look great but it's in the utility room & works fine!!) Now it's nice & quiet at my computer with the fan on low........so I can concentrate on political threads for you all!!

Devil505 · Post by **Devil505** » Wed. Nov. 19, 2008 11:26 am

Spoke to soon!

Came down this morning & the vent fan was off. Checked & the motor was shot. (must have been the rhe0ostat I hooked up)
Disconnected the whole thing, dumped the blower & installed a 6" inline duct booster fan so I'm back in business.

Cold day today...Just 34* at noon!

WNY · Post by **WNY** » Wed. Nov. 19, 2008 11:31 am

Not all motors are variable speed......

Devil505 · Post by **Devil505** » Wed. Nov. 19, 2008 11:34 am

WNY wrote:Not all motors are variable speed......

Yeah!!...Thanks allot Highlander!!

(Just kidding)

LsFarm · Post by **LsFarm** » Wed. Nov. 19, 2008 11:47 am

Some motors don't like to be started on low speed settings.. Like a ceiling fan.. you need to start it on high, then select the slower speed.

Greg L.

Devil505 · Post by **Devil505** » Wed. Nov. 19, 2008 12:56 pm

LsFarm wrote:Some motors don't like to be started on low speed settings.. Like a ceiling fan.. you need to start it on high, then select the slower speed.

I bypassed the speed selector switch figuring it may be the problem & even wired directly to power, the fan is dead. Oh well , I had the inline duct booster anyway so for the cost of a $6.00 duct boot, I'm back in business.

Blackdiamonddoug · Post by **Blackdiamonddoug** » Wed. Nov. 19, 2008 1:16 pm

A reostat add resistance to the circuit
Reostat are very inefficent way to control speed but very cheap.

More expensive
A variac which is a valable transformer change the height of the sinasoidal wave form.
So it can be used to raise or lower the speed of a fan.
Motor not made to be variable speed can be modified by 1/3 speed increase or decrees using a variac
120 volt to 156
120 volt to 84

WNY · Post by **WNY** » Wed. Nov. 19, 2008 3:34 pm

Most of the fans on the stoves are Shaded Pole motors, where others are brush type motors.
More info
https://en.wikipedia.org/wiki/Shaded-pole_motor

These ones can control the blowers

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

Highlander · Post by **Highlander** » Wed. Nov. 19, 2008 9:40 pm

Devil
Not exacly sure what happened with your blower, but most shaded pole motors that are used with these fans can be speed. controlled. If it doesn't run when you bypass the speed control, then the motor is really shot. Perhaps your motor has some kind of thermal overload which may be tripped?

These controls are not rheostats, a rheostat is nothing more then a variable resistance. These devices work by varying the amount of power delivered to the motor by controlling the percentage of the AC sine wave gets passed to the load. They are very similar to lamp dimmers, with the exception that they are designed to handle the inductive load of a motor. I've used them with both the combustion and distribution blowers on a Harman, and had no issues with either.