OT? Why do fans always start out on high?

[DerbyDad03]

Why do the vast majority of variable speed fans start out on high?

Just about every fan I've used that has 3 speeds - window, ceiling, floor, etc. - all go from Off to High to Medium to Slow.

The other day I had the chance to use a fan with a infinitely variable knob and it too started on high and slowed down as the knob was turned.

As far as I know, only my vehicle fans start slow and get faster as the control is turned.

It is easier to build the electronics that way or do manufacturers just assume that we all will use our fans on high most of the time, except in our cars?

[NotMe]

House hold fans come from a time when they were very inefficient and tended to overheat if started on low. (some would not start at all and if that happened could cause a fire) BTW heater fans in the older cars had the same sequence.

[hrhofmann]

They start on high to overcome any tendency to not start moving because of the very low torque on low speed.

[Steve Barker]

actually in the case of ceiling fans and box fans you can change the way the speed switch is wired. I have one ceiling fan that is off-lo-med-hi-off.

[DA]

Most 120VAC fans out there have shaded pole or PSC motors that are low starting torque motors. At the same time, the motors cannot get stalled lest they begin to draw high current and overheat. So, the designers might want to increase the chances of the fan starting normally by throwing it into HIGH first. In this motors high means "high torque", not "high speed" per se. So, HIGH will give it more torque to overcome the staring friction, the inertia and all that hair that found its way onto the motor's shaft.

By the way, not all of them start with high first but you're right, many do. My own fans turned out to be 50/50 in terms of speed out of OFF.

In terms of electronics. it's exactly the same as far as building it but I, too, run my fans on high most of the time. If I didn't need it as powerful, I would have probably bought a smaller model instead.

------------------------------------- /\_/\ ((@v@)) NIGHT ():::() OWL VV-VV

[gregz]

Every fan I use starts out slower when first turned on, but as it heats up goes faster. I'm fully aware of that fact, are others ? Besides, if went to turn off a fan, you might miss off and use low, and not know it.

Greg

[krw]

Because on low they may not have enough torque to start, particularly as they age.

DC motors have more torque at low RPM.

That could be too.

[Robert Macy]

Interesting discussions

such a fan 'needs' to start fast, so while you're there turning on the fan, you might as well adjust it to slower - very clever system design, requiring the Operator to slow it down.

Or, when turning it OFF there is no possibility of error, good point.

No one mentioned the wear and tear on the switch. The german radio/ audio amplifier mfgrs started setting the analog maximum volume at the OFF position so the wear of low volume didn't happen to your switch. Ok turning ON, but a real nuisance when turning OFF - had to wait for silence.