Low speed pedestal fan

[Kenny202]

Anyone know if there is a low speed fan available? I would get a ceiling fan but I am renting. The normal Hatari type pedestal fans are too strong for night time use

 

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[Crossy]

You can reduce the speed of the regular stand fans with a capacitor in series. Try a 4uF motor capacitor from Amorn.

 

A few members have asked this type of question, maybe time for a project thread.

 

[Kenny202]

35 minutes ago, Crossy said:

You can reduce the speed of the regular stand fans with a capacitor in series. Try a 4uF motor capacitor from Amorn.

 

A few members have asked this type of question, maybe time for a project thread.

 

Thanks Crossy. I am actually an electrician lol. Where in series do you put the cap? Active into the motor (line side of the push button switch) or main active coming in or ??

[Crossy]

Bang it in series with either pole of the incoming supply, hide it in the base of the fan.

 

Put a switch across it to short it out to get the normal speeds.

 

You know this, but others may not. You MUST use an AC rated capacitor, the ideal source is motor run capacitors readily available in various values from Amorn.

[Kenny202]

Bang it in series with either pole of the incoming supply, hide it in the base of the fan.
 
Put a switch across it to short it out to get the normal speeds.
 
You know this, but others may not. You MUST use an AC rated capacitor, the ideal source is motor run capacitors readily available in various values from Amorn.

Thanks mate. Have an appliance parts shop near home should have one. Understand require AC. Min amperage rating?

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[Crossy]

21 minutes ago, Kenny202 said:

Thanks mate. Have an appliance parts shop near home should have one. Understand require AC. Min amperage rating?

At fan power levels, just a 4uF (ish) motor run capacitor will do the trick, we're not talking multi-HP motors here ????

 

[Daffy D]

15 hours ago, Crossy said:

 in series with either pole of the incoming supply, hide it in the base of the fan.

 

Put a switch across it to short it out to get the normal speeds.

Hi Crosssy 

 

OK! I'm not at my brightest this morning, could you please explain in little more detail for me.

 

Thanks 

[Crossy]

On 11/30/2018 at 1:58 AM, Daffy D said:

OK! I'm not at my brightest this morning, could you please explain in little more detail for me.

Simple diagrams.

 

 

Top is unmodified fan.

 

Middle just add a series capacitor to reduce the speed.

 

Bottom is the deluxe version with a switch to restore normal fan speeds.

 

[Daffy D]

Thanks Crossy, that's what I thought.

 

A bit confusing when you said "Put a switch across it to short it out" 

 

"A switch to bypass the capacitor" I think I would have understood. 

 

No one else queried your post so obviously it's confirmed that I'm a couple of short planks short of a full load (Sometimes)

 

Cheers   

 

 

[Crossy]

No worries @Daffy D I could have been more succinct in my language, the switch does short the cap mind.

 

This does seem to be a hot topic (reducing fan speed) and since I have exactly the same issue with a Hatari fan that's gale force on setting 1 and has the thrust of a Rolls Royce RB211 (which became the RR Trent) on setting 3 I may do a pukka thread on building one.

 

Wifey is at Mum's tomorrow, watch this space.

 

https://en.wikipedia.org/wiki/Rolls-Royce_RB211

 

[Crossy]

Did a bit of experimenting today.

 

Got 3 x 2uF motor caps from Amorn, 25 Baht each. The ones I got have insulated leads so you can use choc-bloc connectors to put it all together, no soldering.

 

Oddly enough 4uF seems to be the value to make speed 3 on "reduced" about the same a speed 1 on "normal", this seems to be independent of the fan size.

 

This is somewhat empirical as I don't own a tach to check the fan speeds but 2, 4 or 6 uF should do most of us. Lower value = lower speed, just put the caps in parallel for a bigger capacitance (higher speed).

  

[Kenny202]

Any chance you could post a photo of what the cap looks like Crossy [emoji4]

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[Crossy]

I got a handful of these, 2uF @ 25 Baht.

 

The 4uF look similar (slightly bigger) but were sold out in Amorn (Zeer Rangsit), someone else reading this thread perhaps.

 

2 x 2uF in parallel = 4uF - QED

 

 

[lopburi3]

If you have an old step down transformer (230v-115v) it works well.  Have a wall fan attached to such to allow candles to be lit in Buddha room.

[kamalabob2]

Back to the OP question. There are some models of Mitsubishi pedestal fans that are in fact low speed, low air volume, and very quiet. Not every Mitsubishi fan sold in Thailand offers the quiet low volume features. 16" is good, not 12" or 18" fans. I'll post the models which are quiet and suitable for a bedroom.

[sometimewoodworker]

On 12/2/2018 at 7:36 PM, lopburi3 said:

If you have an old step down transformer (230v-115v) it works well.  Have a wall fan attached to such to allow candles to be lit in Buddha room.

Are you running a 220v fan on 115v?

 

Every thing I know about motors says that sustained low voltage kills motors.

[lopburi3]

10 minutes ago, sometimewoodworker said:

Are you running a 220v fan on 115v?

 

Every thing I know about motors says that sustained low voltage kills motors.

Yes I am running 220v fan from 110v output of transformer and works fine on fan motor.  

[Crossy]

On 12/4/2018 at 12:31 PM, sometimewoodworker said:

Every thing I know about motors says that sustained low voltage kills motors.

It does, if you ask the motor to produce the same power output with the reduced voltage.

 

Luckily, fans follow a cube-law speed vs power so reducing the speed (lower voltage) reduces the required power significantly and things don't overheat.

 

So, to follow on from my earlier testing, I built a simple tacho (Arduino to the rescue).

 

My measurements using a fairly new Hatari 18" stand fan.

 

RPM and Power (W)

 

Standard configuration.

Speed 1 - 760 RPM   49.9W

Speed 2 - 880 RPM   55.5W

Speed 3 - 1000 RPM 59.5W

 

With 4uF series capacitor.

Speed 1 - 560 RPM 31.7W

Speed 2 - 640 RPM 35.4W

Speed 3 - 720 RPM 39.3W

 

Adjust your fan from a gentle zephyr to a howling gale.

 

This is a real Zephyr ????

 

Not something you wanted to see in your mirror ???? 

 

My dad used to have one of these (yes ex-plod) as a mini-cab in Leigh (Firs Lane Taxis), nicknamed the "Flying Pig" for some reason

 

 

[Fat Prophet]

On ‎11‎/‎29‎/‎2018 at 4:36 PM, Crossy said:

You can reduce the speed of the regular stand fans with a capacitor in series. Try a 4uF motor capacitor from Amorn.

 

A few members have asked this type of question, maybe time for a project thread.

 

I "assume" that the 4uF capacitor could be installed in a small electric box in an extension cord and plug the fan into that, avoiding the need for a switch? I have a 24" Trojan fan and the cord runs down the outside of the metal pole. Installing a capacitator on the cord would not be attractive as there is no place to "hide" it. The box on an extension cord could be hidden behind a chair on the floor.  I had the fan on "1" (of 3) yesterday and it blew over the Christmas tree 3.5 meters away -- more powerful than I expected. I have a 110/220 converter that I brought from the US when a first came with a few small appliances from the US if I can locate it. The appliances are long gone, but the converter is here somewhere....

[Crossy]

1 hour ago, Fat Prophet said:

I "assume" that the 4uF capacitor could be installed in a small electric box in an extension cord and plug the fan into that, avoiding the need for a switch?

Yup, that's what I have, there's a switch on the box with the outlet, high and low speed range.

 

With a big fan you may need a bigger capacitor to avoid things being a bit too slow. Get a handful of 2uF caps and experiment ????

 

[Pattaya46]

Hi. I bought a mural fan that sadly proved to be too powerful for my condo room. The box didn't say that Speed 4 was "hurricane" !, and even at Speed 1 it blows away many objects in the room . I googled the problem and found this thread and a few other with similar content.

 

I didn't choose the capacitor solution, because I don't like the idea to modify a new device that has several years warranty, and because the reduction of speed is often not very important (20-30%?) or else the fan doesn't start anymore...

 

I choose the easy solution: a small 200-to-110V transformer for about 100 baht online and it works well. Now speed 1 is too slow  but speed 2 is perfect