If in doubt, cook 'em! I did this with my daughter last weekend with a water filled pan on the grill using the grill meat thermometer and another dial thermometer for greater accuracy. We cooked 2 thermometers and she got to see how they both opened and closed where they should (statically). It should be noted that the position of these thermostats is also affected by flow load (according to the FSM), therefore at higher flows they are probably full open before they would be at idle for the same temperature