This is really off topic, but maybe I can get some help here,
or from some one, or from some one some one of you may=20
know who knows how things work. It has to do with the=20
oven gas valve in my old '50's vintage Kenmore range.

The oven worked unreliably, and finally would not ignite.
Examination revealed everything apparently in order, with a
good pilot flame centered in the element which it heats. But
the "thermostat", which appears to be a sealed wire-wound
potentiometer, did not feel right, and did not test consistently
with an ohm meter. Function was restored by drifting in TV
tuner cleaner and exercising the control. Which is to say that
the oven now works like new. When the oven is off, there is
infinite resistance across the "thermostat" terminals. On, there is
a low variable resistance.

Sears has been famous for supplying parts for its stuff, but has
let us down monumentally in recent years. Needless to say,
parts for this old range are not available.

My problem is this -- I do not have the faintest idea how this
system works. There are two skinny cylinders, which are
connected to the main valve by narrow copper tubing, and
the pilot also, which heats one of the cylinders. The other=20
cylinder senses oven temperature at the exhaust vent. And
there are the two wires to the above-mentioned potentiometer.
Although the range has a light and a clock, there is no electrical
power to the oven gas valve.

I can imagine a resistive bridge circuit between the potentiometer
and the heat sensor, assuming it is a thermocouple, maybe driven
by power generated by the device heated by the pilot flame, assuming
it is a thermocouple. However, in my experience, such-looking things
have sometimes turned out to be hydraulic devices containing mercury.
In any case, I cannot begin to guess how the force to open and close
the gas valve is generated.

Please, if you can help me to understand my gas valve, REPLY BY EMAIL,=20
as this is not a topic of general interest. (There does not seem to be
much about this valve on the Internet. It is one where the pilot flame
does not increase when the oven is started.)

For those of you who may wonder why I continue to wonder after
the fault is removed, be informed of the guiding principle:

When and if you do something right, you should always try to find out
how that happened. (Even taking notes!)

--=20
Dick Adams
<firstname> dot <lastname> at bigfoot dot com
___________________
Sourdough FAQ guide at=20
http://www.nyx.net/~dgreenw/sourdoughfaqs.html