​On demand water heaters turn on when you open a hot water faucet and turns off when you close it. The energy that is consumed is only for the hot water being used. Since there is no storage of hot water and thus no constant heating and re-heating of stored water, you are not wasting energy heating water when you don't need it, such as when you are sleeping or not at home. This energy savings translates to dollar savings for you and reduced impact on our environment.

 

Furthermore, since tankless heaters heat water as you use it, you can have an endless supply of hot water, provided you size the unit appropriately. Tankless heaters are also designed to last for
20 years and are smaller than hot water tanks.

 

How do tankless water heaters work?: When a hot water tap is opened, the cold water enters the heater and triggers the heating elements or burners to turn on. Your hot water tap acts as an ignition key for the energy used to heat the hot water you need. The water is then heated
as it flows through the heating elements or heat exchanger. As you change the water flow, a water valve or thermostat controls the heating elements or burner flame to maintain a constant temperature
The amount of energy used is always proportional to the volume of hot water being used. When the hot water tap is turned off, the system shuts down.