Since the crockpot is my primary method of cooking, pretty much since college, and a grognard <pronounced gron-yard> is an old campaigner (Napoleon called the soldiers who came back from Russia with him grognards), I call myself a crockpot grognard.
Not a geezer, not even middle-aged yet...
The old pots cook on low at a solid simmer just under 200 degrees (F). Hi would be maybe 240-ish. If you've got an old pot (especially with a glass lid), you've got gold!
The new ones on low are significantly above boiling, around 220-230 or so, ostensibly for safety reasons. But anything above...