slow down speed of AC FanCoil blower motor


  #1  
Old 03-21-23, 09:03 AM
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slow down speed of AC FanCoil blower motor

hello, i have a central AC Fan Coil with a 3 speed motor within my Condominium. I run the fan of low but find it blows too much air and produces too much noise when i run the AC (the motor works perfectly and doesnt make noise internally, just the rotation and airflow it produces for my samll condo unit) i just dont want to hear the central ac fan running so loud when ac is on

my question is what can i do to control/lower the speed of the blower motor (again, its a 3 speed motor and I only run it on low)

would adding a resistor inline do the trick? is there a device that can run between my 120Volt wire and the low speed wire on my blower motor?

its a 120Volt, 1/5 HP 3 speed ECM motor

any ideas would be appreciated
 
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Old 03-21-23, 09:47 AM
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I would seriously reconsider slowing below your lowest setting. It can damage or cause problems when there is insufficient airflow through the unit. It's less an issue with a gas or oil furnace but heat pumps and AC can freeze up if you don't keep enough air moving through it.
 
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Old 03-21-23, 10:41 AM
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An FCU typically uses cold water supplied by a central chiller for cooling.
There is no way to slow down an ECM motor below it's programmed setting without having the control module reprogrammed.
 
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Old 03-21-23, 11:06 AM
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I made a mistake, the motor is a PSC motor.

my condo has a chiller plant in the basement and pumps the cold water to my condo unit with a supply water line that connects to my FanCoil Unit and there is also a return water line from my FCU...

but the fancoil and motor is mine and connected to the apartments electric, i can cut off power to the motor by a dedicated AC circuit breaker

when you say "control module reporgrammed" I assume your talking about ECM. I made a mistake i have a PSC motor.
 
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Old 03-21-23, 11:27 AM
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Correct.

Not really much of a way to slow down a PSC motor either.
You want to go slower than the low speed tap.
Just reducing voltage to that motor will cause it to overheat.

That would require a VFD (variable frequency drive).
It's an electronic phase shifter to change motor speed by varying the operating frequency.
I'm looking for a cost effective unit. They typically start at $100.
 
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Old 03-21-23, 11:50 AM
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thanks for the reply. would something like this be suitable, or does it need to be more specific for this motor or application? if its not suitable can you post a recommended version...

https://hdsupplysolutions.com/p/kbel...xoCBt8QAvD_BwE
 
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Old 03-21-23, 12:34 PM
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That device says ok for PSC motors of up to 6A.
Just make sure your motor is under 6A.
 
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Old 03-21-23, 02:24 PM
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question, this motor has a capacitor. how would that effect the interaction between this device and the initial starting of the fan coil motor? ( i only plan to reduce speed by 20-30%,,, of lowest speed available on motor)
 
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Old 03-21-23, 02:58 PM
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here are some details of the link i posted...

About this item

  • Designed for Standard 2" x 4" Electrical Wall Box
  • 5.0 Max amps 115 Volts; UL & CSA Approved
  • Not to be used with Capacitor Start or Capacitor Run Motors. Note: Not to be used with gear motors
  • Applications: Fans, Blowers, Fireplace Blowers, Attic Fans, Humidifiers, Ventilators

does it make it unusable for me.... another option?
 
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Old 03-22-23, 08:37 AM
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i spoke to KBElectronics that makes the above Vari-Speed control. They have a device that works with Capacitor motors.... max rating is 3AMPs... but it works for me

KBMC-13BV (H9034) Solid State AC Control
https://www.kb-controls.com/product.sc?productId=106
 
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Old 03-22-23, 07:41 PM
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Have you considered replacing motor with slower one?
If there is slower motor with same physical dimensions, it might be the cheapest option.
 
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Old 03-23-23, 01:47 PM
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I doubt that will work. Ask them if you can send it back if it doesn't work.
I wouldn't expect much for $12.
 
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