Patent ID: 11602241

Abstract:
Control of temperature of water delivered by a dual-stage water heater having an external boiler with a first heater as first stage and an internal duct (water booster) with a second heater as second stage. A control loop based on a measured water temperature in the boiler and controls the first heater. A second loop calculate a reference booster water temperature based on the temperature error at the outlet (difference between a measured outlet water temperature and a reference outlet water temperature) and controls second heater based on error between reference booster water temperature and measured booster water temperature. The reference outlet water temperature depends on type of beverage (e.g. espresso, cappuccino) and includes a temperature profile with different temperature for different sub-beverages (e.g. coffee, milk). Takes into account physical response times, inertia of heater and anticipate sudden changes of reference water temperature at hot water outlet.