we update our 12V/24V DC sumbersible solar water pump thermostat,it can protect motor not overheat,for example,if the thermostat is 100 degree，then when motor temperature reach 100 degree,the thermostat will cut off the electric,motor will stop too,when the temperature drops, the thermostat is closed, and the motor will restart. and for the old thermostat, the contact points of the thermostat are exposed, and sometimes the transportation vibration will cause the contact points to be bad, causing the motor to lose power.