How does a traditional tank heater work? 

The traditional heater has a tank where it accumulates water and heats it little by little and when it reaches the temperature set on its thermostat it turns off. This process can take about 90 minutes. Then, during the course of the day, it turns on and off to keep the water in its tank warm, either because a hot water faucet has been turned on or because the stored water has cooled. In this way, a tank heater wastes energy heating water that probably no one uses. 

What is TERMOTRONIC? 

TERMOTRONIC is also a water heater but tankless and flow activated. This system basically gives you four advantages over a traditional heater.