... how does it work?<br/><br/>I am well acquainted with the usual car type. The bulb reacts to heat, offsets the tension from the spring, and opens the diaphragm.<br/><br/>My M11 thermostat has no diaphragm - it is open! Old one, new one, photos on the web.<br/><br/>How does it control flow?<br/><br/>Matt B