AUTOMATIC ELECTRIC WATER HEATER Precaution The heater must be installed below the overhead water source. Connect normal water line to the water source (Water Tank) and the hot water line (RED) into house system. Install vent pipe or pressure valve to avoid airlock into the hot water system. Open main valve and fill the water heater with cold water. Open several tap or points to allow air to escape from the system. Specially before operating the water heater-be sure that the cold water is passing through the hot water system or points. If so, then switch the water heater ON, otherwise there is every possibility of damaging or burning of the element itself.