Can anyone give me any information on when a fail safe circuit using a
thermocouple or pilot generator for a heater became standard for
household use or when it became mandatory for manufacturers of
furnaces.


I have an Adrews floor heater. Yes it’s VERY old. It doesn’t seem to
have a fail safe circuit. I am very curious as the whether it never
had it or if someone messed with it.

Yes I know all about pushing in and holding down the pilot control rod
to light the pilot but this rod isn’t going down or up, it only
turns.
Yes I know I should replace the entire heater and I am in the process
of replacing it now or very soon. I am simply curious about its
operation that is all. Any historic information you can give would be
greatly appreciated. Thank you.