If it is a a 180 stat that means it just barely starts to open at 180, it may be hard to see it starting to open with your face in a pan of hot steamy water, most of them will not be fully open till around 200. Even if you pull it out of the pan at 180* the open crack would be very small and the stat will be cooled a few degrees before you get it close enough to see the crack and probably closed.