There's a quick way to check- - - -immerse the thermal bulb in a pot of boiling water for a "212 degree" reference, and/or use a cooking thermometer to check the temp in the pot before it get to the boiling point. I use a laser thermometer a lot when diagnosing overheating problems. They're cheap on Ebay, and pretty accurate. Just point the red dot at the top and bottom of the thermostat housing to get an idea what the opening temp is.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!