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I have a pedestal fan which is rotating too fast. It's on the lowest setting yet it's stronger than the highest setting of any other fans I've seen. It's noisy as a drone, unnecessarily fast and i think it consumes more energy than it needs to.

Can I just use an adapter or something to reduce its input voltage so the motor rotates slower? Does it make sense? Would it harm the device?

Thanks,

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  • Hello, and welcome to Home Improvement. Unfortunately, "shopping" questions are off-topic here. Please take our tour so you'll know how best to participate here. Aug 8, 2020 at 15:28
  • Fixing, modifying, adjusting appliances is very on-topic - we recommend many circuit breakers/panels... Of course, there aren't many details here - what kind of fan, what's the current input voltage, etc.
    – FreeMan
    Aug 10, 2020 at 11:04

1 Answer 1

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Reducing the input voltage of a motor cooled by a fan (as your fan's motor is) can cause it to not get enough cooling, slowly cooking the insulation until you end up with an electrical fire. The fan was designed for a certain voltage, and it can be dangerous to run it on another voltage.

Also, unless you were to spend a lot of money for a Variable Frequency Drive, any adapter you would put between the fan and the wall would end up using the energy "saved" from running the fan at a lower voltage. In other words, if the fan was using 100 watts before, in order to reduce the fan power consumption to 80 watts, the "adapter", in the process of reducing the voltage, would use 20 watts.

I would recommend selling this fan and buying a new one that is not as noisy.

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  • I'm sorry for the misunderstanding, I meant the big fans that are used to cool people at summer :) Not sure what it's called in English. Thanks for your answer!
    – wololoo
    Aug 8, 2020 at 5:17
  • Your second paragraph makes no sense. There's no rule that says power consumption must remain constant. Even a series resistor (by far the worst option) could lower total power consumption.
    – Sanchises
    Aug 8, 2020 at 5:55
  • @Sanchises - It can be a bit unintuitive, for sure. But the total voltage across the system must remain constant. How does a resistor lower the voltage that the fan "sees"? By there being a voltage drop across the resistor. And this voltage drop, times the current, equals the power that otherwise would have gone through the fan.
    – IronEagle
    Aug 8, 2020 at 6:42
  • If we say the wall voltage is 100V, and the fan uses 100W, then the current is 1A. And if we then put in a resistor that gives a voltage drop of 20V, then the fan sees 80V, and dissipates about 80W. Depending on the power curve, this would probably be more, as AC motors tend to have a smaller effective resistance the slower they spin. However, that 20V drop across the resistor, with 1A still flowing through it, is 20W of waste heat. 20 + 80 = 100.
    – IronEagle
    Aug 8, 2020 at 6:46
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    @Sanchises - This is an open forum. You are welcome to write an answer incorporating your thoughts on how OP's problem could be resolved. I'm erring on the side of caution, as generally running any appliance on a voltage for which it is not intended will void any warranty, and be a sticking point for insurance if any problem does arise (like a fire).
    – IronEagle
    Aug 8, 2020 at 7:07

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