Boiling water delivers heat and force

Tom Shelley reports on a Dutch domestic appliance built on old but very useful engineering principles By holding water in an insulated tank heated to above boiling temperature, steam force can be used to deliver it under pressure, merely be releasing some of it through a tap. This principle lies behind the 'Quooker' invented in The Netherlands by Henri Peteri. The device delivers a spray of hot water for faster cooking, leading to reduced destruction of taste and nutrients. The tap is push and turn to make it toddler safe, but even if a child does access it, the outflow is less likely to cause bad scalds than a conventional hot tap, because the issuing boiling water comes out as a spray instead of a solid stream. The 3 litre tank is kept heated to 110 deg C. Because it is vacuum insulated, standby power consumption is only 10W. The absence of a pump enormously improves reliability. Heating only the water that is required in an insulated container makes it much more energy efficient than a conventional kettle and safer. A high temperature active carbon filter ensures purity and calcium conversion takes place as the water exits the tap, reducing lime scaling in the tank. The makers say that the filter needs changing only once every three years, when any lime scale in the tank should also be removed. The device has been on sale in The Netherlands for 15 years where it is said to be very popular. It is now being marketed in the UK. Quooker UK