Slowing down an industrial shop fan

SouthLake · Jun 16, 2020

Seeking help from GJ brain trust...
I have installed a 18" shop fan in my shop to help circulate some air. 3 speed 120v fan, on its lowest settings its like a wind tunnel. Unfortunately I dont have ceiling or wall space available for a large slow turning fan. The space is conditioned but I just need some gentle air movement.

It is plugged into a switched wall outlet at the moment. Is there anything I can plug the fan into to slow it down? maybe along the lines of an external dimmer? (although i think that's generally frowned upon for motors) :shocking:

Im thinking maybe something like this could work. I could install it into a electric box with a plug on each side, one into the outlet, and the other to the fan. "Solid State Variable Speed AC Electric Motor Control, 2.5 Max amp, 115V"
https://www.amazon.com/dp/B000F9B712/?tag=atomicindus08-20

its a sealed motor, 3 speed pull chain, this is the fan:
https://www.globalindustrial.com/p/...tation-fan-18-blade-diameter-18-hp-wall-mount

LS6 Tommy · Jun 16, 2020

I can't tell what type of motor your fan has. "Sealed" isn't a motor type, it's a motor frame description. There isn't enough info.

Tommy

SouthLake · Jun 16, 2020

The sticker on the motor says 120 Volts 60hz 2.2amps

Bert_ · Jun 16, 2020

Your motor needs to be either PSC or shaded pole which most fan motors are.

SouthLake · Jun 16, 2020

I don’t know what that means :headscrat

nadogail · Jun 16, 2020

Maybe the fan dealer or the manufacturer can help.

SouthLake · Jun 16, 2020

Ok I did some digging, it says its PSC type. im not sure what that means as far as my options to tame this thing.

Innovate1 · Jun 16, 2020

Permanent Split Capacitor - It's a split phase induction motor with a capacitor that stays in the circuit. The capacitor provides the phase shift to get a rotating magnetic field. Speed control reduces the voltage so the slip increases (the field rotates at a constant speed based on line frequency but the rotor doesn't go quite as fast). The losses go up as the slip goes up but for a fan the load drops rapidly as the speed decreases so it usually works ok. The control you posted says it can control PSC type motors.

SouthLake · Jun 16, 2020

Thanks guys, I will try that controller out and see how it goes. I ordered this one too I will try them both.
Tjernlund SCP Plug-in Fan Speed Control
https://www.amazon.com/gp/product/B003IOHBHK/?tag=atomicindus08-20

SouthLake · Jun 17, 2020

I asked them if the motor was brushless and their response was "The Motor is a split magnet motor, but it is not brushless"

Does that change what device i can use to slow it down?

Innovate1 · Jun 17, 2020

Not sure what a split magnet motor is and I work with motors every day. If it is a PSC motor it doesn't have brushes - so you could say it is brushless, i.e. no brushes. But typically the term "brushless" is applied to permanent magnet motors that use electronics for winding switching instead of brushes - electronically commutated. They may be just saying it isn't electronically controlled. If it has magnets it would most likely have brushes. Are you sure what you thought was "magnet" wasn't some other word?

SouthLake · Jun 17, 2020

Thanks Inno, I asked them to clarify wtf "split magnet, not brushless, PSC motor meant".

this was an inexpensive unit, they are only about $120. If I could safely slow it down with one of those two devices I ordered I'd like to run it most of the day. As it is now, on low, it is stupid loud and powerful, almost unusable.

This was from their spec sheet:
MOTOR: 3-Speed, 120V, single phase, sleeve-bearing, totally enclosed, permanently lubricated, PSC type SWITCH: Pull Chain

larry_g · Jun 17, 2020

Have you tried cutting out a cardboard donut to block off some of the air coming into the fan?

lg
no neat sig line

Bert_ · Jun 17, 2020

You know the motor is PSC type. That's all that matters, don't worry about the other descriptions.

Set the fan on HIGH and use the speed control to slow it down

SALIV8 · Jun 17, 2020

Id probably put a filter on the intake side and see if that helps plus you clean the air at the same time.

SouthLake · Jun 17, 2020

Ah ok, thanks bert, Stuff should be here tomorrow. Will report back.

SouthLake · Jun 18, 2020

It works!! Fan speed is very slow and quiet. However this works best when the fan speed is set to low and the modulator thing is also set to low. If the fan is set to high as suggested it’s too much. Is it ok to run it in low / low?
I just don’t want to set my shop on fire

Bert_ · Jun 18, 2020

What fan control did you get? Most of them can be adjusted very slow. Does your have a minimum speed adjustment hidden behind the plate? It should be set so the fan can be set very low but not stall.

SouthLake · Jun 18, 2020

Below, is the one that works best so far, the fan isn’t buzzing, I don’t feel heat on the device and the (sealed) fan motor is a toasty 155°F if it is running on high without the extra controller or on low with controller on low. I can start it from the wall switch, no stalling, spins right up.

Tjernlund SCP Plug-in Fan Speed Control
https://www.amazon.com/dp/B003IOHBHK/?tag=atomicindus08-20

Innovate1 · Jun 18, 2020

"If it's not on the verge of burning up it's over designed."

Not a motto I go by but it seems like some do. Seriously, they are designed to run hot. If it isn't any hotter on the low speed than it is running at full speed you should be ok.

SouthLake · Jun 18, 2020

lol truth
Something so simple but there was more to it than I casually figured. Thanks for all the help here guys.

rsanter · Jun 18, 2020

Check the motor temps.
Running a motor for extended times at a slower/slow speed does not provide sufficient cooling to them and you can overheat them.

Can you put the fan on high and then aim it in a direction that will get all the air on the shop moving verses having the fan blowing on you?
Example would be to aim it down a wall to get all the air circulating or aim at the ceiling to bounce off and tumble the air

Bob

SouthLake · Jun 18, 2020

I think with sealed (industrial type) motors there is no airflow to cool them, they are sealed, and run hotter than motors that are open. I dont know what a normal temperature would be, I can only compare it to running on high without the speed device. Temps are the same at both speeds when I shoot the back of the motor.

The mini-split is in a poor location, but with the fan in the corner circulating a little air across the temperature is more even and the thing isnt roaring like a wind tunnel.

LS6 Tommy · Jun 20, 2020

The speed controller you originally linked to is not supposed to be used with PSC motors. It will eventually burn out. IDK about the Tjernlund controller you have now, but since it's listed for fireplace motors which are shaded pole, it's also probably not rated for PSC motors. Most all of those controllers are for shaded pole motors.

Tommy

SouthLake · Jun 20, 2020

well ***t.
I have this one on hand as well, I would have to make a box for it.
Solid State Variable Speed AC Electric Motor Control, 2.5 Max amp, 115V, # K177-1002

https://www.amazon.com/dp/B000F9B712/?tag=atomicindus08-20

"Control provides infinite variable speed for shaded pole and PSC motors"

LS6 Tommy · Jun 20, 2020

LS6 Tommy said:
The speed controller you originally linked to is not supposed to be used with PSC motors. It will eventually burn out. IDK about the Tjernlund controller you have now, but since it's listed for fireplace motors which are shaded pole, it's also probably not rated for PSC motors. Most all of those controllers are for shaded pole motors.

Tommy

SouthLake said:
well ***t.
I have this one on hand as well, I would have to make a box for it.
Solid State Variable Speed AC Electric Motor Control, 2.5 Max amp, 115V, # K177-1002

https://www.amazon.com/dp/B000F9B712/?tag=atomicindus08-20

"Control provides infinite variable speed for shaded pole and PSC motors"

*EDIT!!*

I misread the link. That controller is OK for PSC motors, just not capacitor start or capacitor run motors. Serves me right for not wearing my cheaters when I read.

Tommy

SouthLake · Jun 20, 2020

Thank you for taking the time to check. I may wire up the solid state one just to see as an experiment. But right now the Tjernlund is working well. I wish i had the space for a big slow ceiling fan but having a car lift, and 10' ceiling there is no room to work with.

SouthLake · Jun 20, 2020

Ok so I made a box for the solid state one. With this set up I can lower the fan speed way down while the fan switch is set to high as suggested earlier. There was a pot switch I adjusted down to help set how low, low is. The motor is running about 10 degrees cooler too.

Using the Tjernlund controller, the fan speed must be set to low, and the device to low in order for it to work...

solid state:

Tjernlund

Slowing down an industrial shop fan

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