On Sun, 13 Jul 2008 13:19:20 -0500, Puddin' Man
wrote:

On Sun, 13 Jul 2008 13:07:21 -0400, mm wrote:

On Sun, 13 Jul 2008 11:58:36 -0500, Puddin' Man
wrote:


Detached 2-car frame garage with only 2 tiny gable vents. Way too
hot in summer. I installed a 12" exhaust fan in a window frame
many years ago.

The thermostat is a series of metal blades (bi-metal) and a
pair of contact points like in old cars, mot'cycles. It wouldn't
shut off last summer, I filed the points down like I'd done
years ago with cycles. Worked for last season.

This season I file 'em down, add some dielectric grease, it works
for a few hours, then fails to shut off.

So the contacts are fused together?

Nope.

Or the spring is no good and they
stick together even though not fused?

Nope.

Or it's not really dielectric
and the current is running through the grease?

I'd be surprised if they can fuse in a few hours, so what is the
problem?
Markings on the tstat:
BIMET
70F A76
FP 21
6-22 HOOD

Any chance of picking up a replacement tstat?

You don't need the exact thermostat. Thermostats come with roof fans,
so they probably sell them separately too, at least on the web,
probably from any company that sells roof fans, and maybe from the
places those companies get them from.

I need something cheap, like what the fan came with.

Any tips, suggestions, ways to "fix" the old tstat?

Mine seems to be stuck closed also, although maybe only sometimes (how
could that be??), but it's 25 years old. Came with a roof fan.

I guess the dialectric grease is meant to cut out the arcing, is that
right?

Yes.

Filing I think is mostly to enable points that don't conduct
to do so.

Which is the opposite of your problem.

Unless your points are sticking together, but you don't
mention prying them apart.

I didn't have to. Last nite I pulled the AC plug so I could
sleep w/o burning up the motor. This morn the contacts
were not fused. Hard to tell what happened yesterday
when it failed to shut off.

Well, after you pulled out the plug, did the contacts come apart by
themselves?

If not, it seems to me they are fused or the spring is not strong
enough.

Or there's some hidden force, some magnetic field in your house.

What or what else could be the explanation?

P

" ... and the bees made honey in the lion's head."
- from "If I Had My Way", Blind Willie Johnson