A beverage maker , comprising a heating system ; a temperature sensor operably coupled to the heating system ; a controller configured to receive measured temperature signals from the temperature sensor; and a tangible, non-transitory computer-readable storage medium having instructions stored thereon for that, in response to execution by the controller, cause the controller to perform operations comprising: receiving, by the controller, a series of measured temperature signals from the temperature sensor; calculating, by the controller, a change in temperature using the series of measured temperature signals; calculating, by the controller, an efficiency of the heating system based on the change in temperature; estimating, by the controller, a scale buildup based on the efficiency of the heating system; and storing, by the controller, at least one of the estimated scale buildup or the efficiency of the heating system in a heating system performance database; wherein calculating, by the controller, the efficiency of the heating system based on the change in temperature comprises: determining, by the controller, an expected change in temperature using a system thermal model; and comparing, by the controller, the change in temperature to the expected change in temperature. a heating system ; a temperature sensor operably coupled to the heating system ; a controller configured to receive measured temperature signals from the temperature sensor; and a tangible, non-transitory computer-readable storage medium having instructions stored thereon for that, in response to execution by the controller, cause the controller to perform operations comprising: receiving, by the controller, a series of measured temperature signals from the temperature sensor; calculating, by the controller, a change in temperature using the series of measured temperature signals; calculating, by the controller, an efficiency of the heating system based on the change in temperature; estimating, by the controller, a scale buildup based on the efficiency of the heating system; and storing, by the controller, at least one of the estimated scale buildup or the efficiency of the heating system in a heating system performance database; wherein calculating, by the controller, the efficiency of the heating system based on the change in temperature comprises: receiving, by the controller, a series of measured temperature signals from the temperature sensor; calculating, by the controller, a change in temperature using the series of measured temperature signals; calculating, by the controller, an efficiency of the heating system based on the change in temperature; estimating, by the controller, a scale buildup based on the efficiency of the heating system; and storing, by the controller, at least one of the estimated scale buildup or the efficiency of the heating system in a heating system performance database; wherein calculating, by the controller, the efficiency of the heating system based on the change in temperature comprises: determining, by the controller, an expected change in temperature using a system thermal model; and comparing, by the controller, the change in temperature to the expected change in temperature. <EOS>