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Sjouke Burry[_5_] Sjouke Burry[_5_] is offline
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Default Do thermal fuses fail from old age?

The Daring Dufas wrote in news:jkf3na$uvu$1
@dont-email.me:

On 3/21/2012 11:03 PM, jeff_wisnia wrote:
Over the years I've had a few thermal fuses in houshold appliances go
open for no apparent reason. When I've replaced them with ones with

the
same temperature rating they stayed working fine for years more.

A couple of days ago our three year old Bunn coffee maker quit,

because
a 141 degree celcius overtemperature thermal fuse on the water tank
opened. It might possibly have happened because the water tank
thermostat stuck closed, but after I repaired it the thermostat cycled
just as it should.

I was suprised to find that there were TWO identical thermal fuses
connected in series located right next to each other, the bodies were
actually touching. That seemed like a belt and suspenders approach,
unless there's a significant likelihood that a thermal fuse won't open
when it should?

Comments?

Thanks guys,

Jeff



I could understand parallel fuses because one may not handle the
current. Perhaps in series it's safer because the unit will shut
off if one fails to open? o_O

TDD

That is because they dont trigger on current(mainly).
They trigger when their surrondings get to hot.
Imagine a current carrying spring, soldered to the other
side with solder of a particural melting temperature.
Of course you can also heat them by massive overload in
current, but that is not the way they ought to work.