PTC water heater, shower water heater. The power can be adjusted itself. When the water is dried, it's no trouble. Notice for manufacturer and ... to maintain temperature of water is very excellent and also low cost.For getting higher power, let water flowing or convection, ... about 6W /cm2at 25 waterfor immerging heater or transflux heater. The higher temperature is the water, the lower is the power. ...