Abstract: In a coffee maker (1) having a boiler (6) and heating means (62) for heating a content of the boiler (6), safety measures are taken to prevent breakdown of the coffee maker (1) in the case in which the heating means (62) are activated while the boiler (6) is empty. The coffee maker (1) comprises a controller (10) having a memory (15) in which a flag indicating a filled state of the boiler (6) can be raised, which controller (10) is programmed to activate the heating means (62) to supply reduced heating power if the memory (15) does not contain the flag. A situation in which the boiler (6) gets overheated, even if the heating means (62) are shut off after having been operated, is prevented thereby.

Abstract: A method for operating a boiler of a device, such as a coffee maker, includes initial steps aimed at determining whether the boiler is filled with water or not. In the process, the insight that the thermal behavior of an empty boiler differs from the thermal behavior of a filled boiler is applied. A heating element of the boiler is used to generate heat during a predetermined length of time. As a result, the temperature inside the boiler starts to change. At a certain point, the temperature change over a time interval having a predetermined length is measured. Subsequently, the measured temperature change is compared with a reference temperature change. In case the measured temperature change is larger than the reference temperature change, it is concluded that the boiler is empty and needs to be filled before the heating element is activated again.

Abstract: A method for operating a boiler (6) of a device (1) such as a coffee maker comprises initial steps aimed at determining whether the boiler is filled with water or not. In the process, the insight that the thermal behaviour of an empty boiler differs from the thermal behaviour of a filled boiler is applied. A heating element (62) of the boiler (6) is used to generate heat during a predetermined length of time. As a result, the temperature inside the boiler starts to change. At a certain point, the temperature change over a time interval having a predetermined length is measured. Subsequently, the measured temperature change is compared with a reference temperature change. In case the measured temperature change is larger than the reference temperature change, it is concluded that the boiler (6) is empty and needs to be filled before the heating element is activated again.

Abstract: In a coffee maker (1) having a boiler (6) and heating means (62) for heating a content of the boiler (6), safety measures are taken to prevent breakdown of the coffee maker (1) in the case in which the heating means (62) are activated while the boiler (6) is empty. The coffee maker (1) comprises a controller (10) having a memory (15) in which a flag indicating a filled state of the boiler (6) can be raised, which controller (10) is programmed to activate the heating means (62) to supply reduced heating power if the memory (15) does not contain the flag. A situation in which the boiler (6) gets overheated, even if the heating means (62) are shut off after having been operated, is prevented thereby.

Abstract: An apparatus for preparing beverages, such as a coffee brewer, has a device for measuring the periods of time during which the heating element is switched on and off by a thermostat connected in series with the heating element. The ratio between the on period and the off period is computed. If the off period is smaller than the on period, an indication is given that there is scale deposit in the water pipe. If the off period is greater than the on period, an indication is given that brewing has finished and, optionally, the heating element may be switched off permanently.

Abstract: An irradiation device including a series arrangement of an ultraviolet radiation source (5), a first switch (3) and a second switch (4). Under normal conditions the radiation source (5) is switched on and off by the first switch (3). The second switch (4) is operative only if the first switch (3) fails. By means of a simple circuit (7, 20, 17, 6; R), the defective device cannot be switched on again.