The heat controller is required when purchasing an electric boiler to allow you to adjust the boiling rate of your electric boiler between 0% and 100% of the boiler's rating.
This prevents "surge boiling" (associated with thermostatic control) and ensures stable boiling at the desired rate. The faster a mash boils the less you would be able to distinguish between heads hearts and tails. Likewise the slower the boiler boils the better you would be able to distinguish between the cuts.
Suitable to handle up to 16 Amps.
Heat control should not be confused with "temperature control": A thermostat controls the temperature and allows a boiler to switch off at a certain temperature and stops boiling. As the mash in a boiler cools down the thermostat will switch on again and starts boiling. This on/off switching leads to "sporadic surge boiling" that totally upsets the equilibrium in a distilling column. This causes highly unpredictable distilling results and is not desirable.