How Do Instant Hot Water Tankless Water Heaters Work?
Tankless water heaters only heat when water is flowing through them. When a hot water tap is opened, cold water flows into the heater unit and triggers either electrical heating elements or gas burners to turn on. As the water continues to flow through the tankless heating unit, it continues to be heated until it reaches the desired temperature (usually in the range 100F to 140F). When you vary the water flow rate at the faucet, a water valve or thermostat controls the amount of heat supplied so that water exiting the tankless heater unit is maintained at a constant pre-set temperature. For any particular input cold water temperature and pre-set exiting hot water temperature, the amount of energy used by the tankless heater unit is therefore proportional to the flow rate of hot water demanded. When the hot water tap is turned off, the system shuts down.
