A pump at the tank or tankless heater, or installed under the sink, forces the lukewarm water from the hot supply line into the cold supply line. If a dedicated return line is used it returns the lukewarm water to the heater.
A sensor/switch (Aquastat) built into the pump or an Aqua-Flash® or ODR Superflow™ By-pass valve transfers the lukewarm water into the cold pipe. The valves maintain average 93° F (34° C) at the sink. The under sink pump starts when temperature drops to 85° F (30° C) and stops when it reaches 104° F (40° C). The pump runs about 3 times an hour for 2 minutes. A built-in 24-hour mechanical timer allows the user to set the time when he wants instant hot water. An ON DEMAND button/motion sensor or app can also activate the system
US Patents, RTM, 9,864,647, D834, 145, 8,083,500, 8,303, 184, 9,328,736, 10,612, 793, 5,501,838, 4,507,949, 11,193,605. Canadian Patents 2,883,495 & 2,935,949