Is externally bonded to the bottom of the tank. It is insulated with special foam and has excellent thermal conductivity. The live wire filament occupies only about 15 % of the actual heating surface. Protects water tanks from freezing at temperatures down to -40 °C. Overheating safe, thermostatically controlled high-tech product with a special adhesive coating. Easy mounting by glueing onto all fresh and waste water tanks, also for bumps and protrusions. If the outside temperature of the tank drops below 7 °C, the Ultra-Heat tank heater begins to heat up itself and the water. If the outside temperature of the tank rises to 19 °C, the heater stops heating. Thanks to these switching stages, the water is kept frost-free.