A while back I asked for help with an oven thermostat problem.
Some persons kindly provided some support.
But I misreported the case.
I fix that now:
Finally, I detached and opened the "thermostat", which is a device
located at the top of my 50's (60's?) Kenmore gas range. It has
two wires coming out, and a copper capillary tube (which I did
not previously report because I did not see it).
The problem had been that the oven gas did not turn on reliably.
The capillary copper tube is to the oven temperature sensor. In=20
the "thermostat" it goes to a bellows. Presumably the oven-
temperature sensing system is filled with an expansible fluid like=20
mercury. The "business end" of it is a narrow cylinder which senses=20
the oven temperature at the exhaust duct of the oven.
The "thermostat" is a cam which decides when the bellows will open
a switch. That switch, with little doubt, sends the output of the pilot
sensor (which, with little doubt, is a thermocouple) to the oven gas
valve, which is located in a box below the back of the oven/broiler
burner..
At the low end of the thermostat rotational travel, the contacts are
fully open, by a considerable increment.
I learned from one correspondent that this system is called a "millivolt
control" presumable because of the lowness of the pilot-sensing=20
thermocouple electrical output.
Now that I see what it is, I really like it. It seems to have lasted =
more
than a half-century with no more trouble than dirty switch contacts.
But time must yet tell that cleaning the contacts (with crocus cloth)
fixed the problem. Today's stoves may have electronic ignition. =20
So far the electronic ignition devices I have come across did not
distinguish themselves by their high reliability. In any even, in =
stoves,
they take mains power, which, with terror (terrorism!) we can count
on less nowadays.
I must apologize to the persons to whom I reported that the "thermostat"
seemed to be a rheostat. It is not. Actually, the thermostat is the =
entire
system which controls the oven heat. The "millivolt control" is =
probably
among the simpler systems, if not the simplest. Simplest tends usually
to be the most reliable.
The old Kenmore range detaches from gas with a union under the stove
top at the level of the burners. So you just raise the top, uncouple =
the
union and pull the stove out, after turning off the gas in the basement.
New stoves have the connections at different places, apparently=20
involving that you should pull out the stove slightly, and send a midget
in to do something with a flex line, assuming you have a stove which
is enclosed on both sides and the back by walls and counters like
we do.
So I hope that my repair, consisting of cleaning the contacts in the
"thermostat", will work out. Otherwise, it is a new stove, and a =
plumber,
I guess, since Mrs. Adams does not trust my gas-fitting skills, and=20
since I have not figured out how to do an installation with a flex line
without a midget. But, in the meantime, I am looking for a cheap
range with "millivolt control" for the oven, and stainless-steel burners
ignited by pilot flames. Those are good because you can pull them
out a soak the out in the dishpan when they get dirty. Presumably
such things are still made for 3rd-world people who cannot not afford
the kind of complexities which make our lives very expensive.
--=20
Dick Adams
(Sourdough minimalist)
<firstname> dot <lastname> at bigfoot dot com
___________________
Sourdough FAQ guide at=20
http://www.nyx.net/~dgreenw/sourdoughfaqs.html