... mm, 15, 18, 20, 24, 30PCS available Backup electrical heating rod: 1500w German coating technology of evacuated tubes, ... digital controller for the solar water heater to realize display of water level, water temperature and automatic water filling. Imported painted steel, ... . 3. Avoid the promblem came from water level controller malfuction which could cause water flow out. 4. The effect of ...