Tiny thermostat for exhaust fan

[Puddin' Man]

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.

Markings on the tstat: BIMET 70F A76 FP 21 6-22 HOOD

Any chance of picking up a replacement tstat?

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

TIA, Puddin'

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

[mm]

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

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.

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? Filing I think is mostly to enable points that don't conduct to do so. Unless your points are sticking together, but you don't mention prying them apart.

[willshak]

on 7/13/2008 12:58 PM Puddin' Man said the following:

Home Depot sells thermostats for their Master Flow gable vents. It may work on yours. If not, bring it back.

[N8N]

back.http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?sto...> or:

Thanks for reminding me, I need to pick one of those up for my garage. either the fan or the thermostat is bad, and I'll need it for the house eventually anyway (want to add a vent fan for the house)

nate

[Puddin' Man]

Nope.

Nope.

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

Yes.

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.

P

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

[mm]

Which is the opposite of your problem.

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?

[RBM]

or:

That should work fine, or any single pole attic fan thermostat you can get your hands on

[CJT]

I got my replacement at Lowes. I think it was about 15 bucks, and much better quality than the one that came with my fan. Unless your time is free, it seems like an easy choice.

[Puddin' Man]

> or: >

Thanks, but ...

I need something cheap, like what the fan came with. The fan ItsOwnSelf could roll over and die most anytime. When last I peeked, the selection of 12" exh. fans for replacement looked pretty bleak.

P

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