Six probes, numbered TE [4–9], have been used to measure the external temperature of the tank and the pot, in order to assess the heating behaviour, and collect the most available data. They have been realized with Chromel/Alumel cable type GG- 30-KK, and they have been fixed to the device with an epossidic bicomponent resin. Two more Chromel/Alumel thermocouples with insulated hot junction have been used to measure the temperature of the aqueous extract (coffee) in the little column of the top pot. A sketch of the coffee maker with a schematic view of probes positioning is presented in Fig. 2a. 2.4. Pressure probe The vapour–air mixture pressure in the lower tank has been monitored by means of a Wheatstone bridge-based sensor, produced by Kulite. The model used, XTEL-190-100D, is a 0–7 bar (100 PSI) pressure range transducer, operating in differential mode, with temperature compensation between 80 "C and 275 "C. 2.5. Mass flow measure For detecting the water level inside the tank at different height, eight resistive circuits have been used