You can use the faucet traditionally but you can also use it to save water: 1. pushes the lever down until it locks : the cold water present in the hot water pipes is quickly directed to an expansion tank. 2. when the hot water reaches the faucet it causes dilation of the thermostatic element that unlocks the lever enabling it to return to the neutral position under the effect of a return spring. 3. the user can lift the lever and have hot water in a conventional manner without wasting any cold water at all. The cold water contained in the expansion tank will be reused automatically to satisfy next demand for cold water. Several circuitry configurations are possible to better suit the customer expectation. The waiting time for hot water does not suffer of the presence of an aerator.
The challenge that was addressed is to reduce the waiting time for hot water to the strict minimum without wasting any water and any energy at all. To reduce the waiting time for hot water most houses are equipped with a hot water looping and a circulation pump a huge hidden wasting of energy which is deprecated to heat the walls of the house in summer as well as in winter stupidly wasting up to 20% of the full house energy consumption. The installation of a water-saving faucet aerator reduces the flow of water by 50% but it therefore double the waiting time for hot water which is often unacceptable. I designed a faucet that has the same functions as a traditional water mixer but that has an additional output orifice and a thermostatic element to detect the presence of the hot water. The tap for the shower will even allow you to get in the shower before opening the tap without risking to receive a single drop of cold water.; Some prototypes have been operating for 4 years and saves 10 gal. of water/day...