Rinnai REU-KM3237FFUD-E Installation And User Manual page 21

OPERATION - PRINCIPLE
Ignition
Press ON/OFF Button of Remote Controller to turn on unit and the remote
controller display and priority LED will light up.
When a hot water tap is opened the Water Flow Sensor revolves and sends a pulse
signal to the Printed Circuit Board (PCB.) When the PCB detects water flow it
compares the measured temperature to the temperature setpoint
begins the ignition process with the Combustion Fan Motor starting first.
Once the air proving is made the Main Solenoid Valve and Change-over Solenoid
Valves are opened and the Burner is lit by the sparking Igniter.
Temperature Control
Once the Flame Rod proves ignition the Infinity modulates by controlling the gas
rate, combustion air, and water flow to precisely heat the water. This control is done
by measuring the outgoing water temperature with a Thermistor.
Standby
When the hot water tap is closed the PCB no longer receives a pulse signal from the
Water Flow Sensor. The PCB shuts the Main Solenoid Valve and Change-over
Solenoid Valves and the Burner extinguishes.
HOT WATER SUPPLY OPERATION
21
If required it