... 70 °C free setting. 3, hot water circulation heating function: when using ,open any hot water point for 3 seconds then turn ... lower than 3 °C, the system automatically starts the circulating pump, driving water heaters heating, when the temperature reaches the set ... " " button and the " " button, set the appropriate water temperature (system hot water temperature is 40 °C, Can choose between 25-75 ...