When a hot water tap is opened the unit detects the flow.
The flow sensor activates to determine the amount of hot water needed.
The igniter activates.
The gas control valve opens to supply the correct amount of gas.
The fan and venturi activate to provide the correct amount of gas and fuel.
The premix burner ignites providing a flame to heat the water.
Cold water is pre-heated in the secondary heat exchanger.
Pre heated water passes from the secondary to the primary heat exchanger.
The unit determines outgoing set temperature and adjusts the flame to heat the water.
Heated water moves to the buffer tank.
Desired hot water amount delivered to the faucet.