Slowing down motors/fans by adding caps?

[sinsa]

hi guys/girls

just a quick question to the electrically minded.

i have two 25cm extractor fans i am fitting in to my basement which i bought slightly 'oversized' in the hope i could run them at half speed so they are quiet but stil offer a fairly O.K. air flow over a smaller bladed model.

the fans are 34Watt at 220volts 60Hz.

as far as i understand, i simply need to add a capacitor to the circuitry in series, is that so?

i opened the casing and found:

im guessing the brown one is a 'starter' capacitor? - but i may be wrong.

it is labeled "2PW1.0V AC 300V HAN SIN".


so based on the spec, what spec capacitor should i add to the circuit to 'half' the fans speed and where in the series should it be located?

will i run into any fire risks or other problems in doing so?


many thanks to anyone who can chime in!

 

[suat]

You cannot use a capacitor to reduce the fan speed. That capacitor you see is there to avoid the sparks when you switch off the power to the fan. You must use a resistor in series to reduce fan speed. The resistor reduces the voltage to the fan, thereby reduing the speed.

 

[americanaudiophile]

You could try connecting the fans in series. I have not done it with 220v fans but it works fine with small 120v fans. Series means that you would connect the one lead of the first fan to power the second to one lead of the other fan and the second lead of that fan to power. This reduces the voltage to 110v on each. It may not work if the fans won't start on 110v which is possible. I would check with the fans maker before trying this.