When you need to replace it?Replacement of your transducer may be required if no mist is being produced, or if the fire cuts off after 30 seconds.There are several other components which may also contribute to lack of mist, or premature cutting out ?Faulty lamps; ?Faulty sump fan unit; ?Build-up of calcium deposits; ?Lack of mist, or premature cutting out; ?Insufficient / incorrect water level in the tank; ?Damage to the mist nozzle or incorrect fitting of the transducer; Tip: --This part will not fit Opti-Myst models that are fitted with an all-in-one sump and transducer assembly. --The approximate life-span of this transducer is 3000 hours. --To prolong the life of your transducer, please always use filtered water in your Opti-Myst fire as this will help to prevent the build up of limescale. Please note that filtered water should not be confused with distilled water.Legal Disclaimer--"Transducer that can be used with Dimplex." This transducer is not sold or created by Dimplex.