Product details:

Silver Rinnai BC-100V-1. Bath Fill Tankless Water Heater Remote Controller with 98-140F Temperature Range The bath fill function allows a preset amount of water at a selected temperature to be run into the bathtub automatically. No special valve or accessory is needed to use this function aside from the BC-100V-1 controller. A few seconds after bath fill is selected a voice prompt will say The hot water system is ready. Open the hot water tap. Once the preset amount of water has been reached the water heater will automatically shut off the flow of water until the bath fill mode button has been pressed again to turn it off.