If you put a t stat in a pot of boiling water, how much should it open?

I just dropped a 195* t stat in a pot of boiling water. It opened about 1/8" if an inch.

Is this a bad tstat, or working normally?

It should open a bit more than that. I think water boils at 210* so that should be hot enough. YOu should see the spring compress I beleive to about 1/4" and maybe a bit more.

Water Boils at 212°F at Sea Level Standard Day Pressure, 29.92 inches of Mercury. The lower the atmospheric pressure the lower the temperature water will boil.

If you live in the Mountains, the water could boil at quite a bit lower, maybe near 200°F. That is why you see some cooking instructions that will tell you to add boiling time for higher altitudes, have to make up for the lower boiling temp.

BUT, why bother, a new T-Stat is $3-$5, just get another one and be done with it.

An interesting note, while we're on the subject. The reason you pull a vacuum on an system for 1/2 hour after its been open and exposed to air, is to remove any moisture from the AC system (water will kill AC systems). That is because water will boil at 40°F in a vacuum.