On 9/5/2008 4:03 AM Rheilly Phoull spake thus:

Mikepier wrote:

On Sep 5, 4:10 am, Rheilly Phoull wrote:

Bob F wrote:

I've seen a number of older exhaust fans that start very slowly. Turn them on,
they barely turn for up to several minutes, then finally speed up fairly quickly
to normal operating speed. Can anyone suggest why this happens, and a way to fix
them to operate properly?

First thing to try is lubing the bearings I would think

If you are talking about the roof attic fans, the motor might be
starting to go. They sell replacement motors at Lowes or HD and they
are easy to change.

Sure, that will fix it but having spent a large part of my work life
sorting that sorta stuff I can tell you a lot of the time the motor runs
away with no attention until it stops or exhibits the symptoms described.
The manufacturers provide ports to apply periodic lubrication which are
by and large ignored by the average punter. A slow start is almost
certain to be an underlubricated bearing or one that has been worn out
by long usage or underlubrication, usually both.
Nowadays the cost of professional maintenance can exceed the cost of a
replacement (assuming you DIY) so there ya go. For me there is nothing
to lose with trying a squirt of light oil on the bearings before
spending ya moola :-)

True that.

To which I would add two things: 1) Most motors will last forever if
maintained. They rarely "burn out", but simply get gunked-up bearings.

2) If squirting some oil into the bearing cups doesn't do the trick,
then it's time to take the motor apart, clean and lube everything, and
put it back together. Helped a friend do that to an exhaust-fan motor
that was thickly coated with cooking grease and just sat there and
hummed. We knocked it apart (had to use a cold chisel around the cover
seam), whereupon one of the armature wires broke off. No problemo: a
little soldering-iron action plus some heat-shrink insulation fixed
that. Soaked the bearings in paint thinner, cleaned them, lubed and put
together. Now it works like new.


--
Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral.

- Paulo Freire