Final answer:
On-demand electric hot water heaters automatically heat water when a hot water tap is turned on and do not have a traditional on/off switch.
Step-by-step explanation:
On-demand electric hot water heaters, such as the one described in figures 20.44 and 20.37, are designed to provide hot water as needed. Typically, these units do not have a traditional on/off switch like other appliances because they operate automatically.
When a hot water tap is turned on, the unit senses the flow of water and begins to heat it, providing instant hot water. When the tap is closed, the flow stops, and the heater turns off automatically. This efficient system ensures that energy is not wasted in heating water that is not being used.
The lav water heater, also known as an on-demand electric hot water heater, does not have an on/off switch. Instead, it operates based on demand, heating water as needed. When a hot water tap is turned on, the water flows through a heating element in the water heater, and the water is heated quickly.
As soon as the tap is turned off, the heating element turns off, and the water stops being heated. This design allows for energy efficiency, as the heater is only active when hot water is needed.