Rinnai FUA-E, Service Manual

Page: 10 / 67

10
HOT WATER SUPPLY OPERATION
Ignition
Press ON/OFF Button of Optional Remote Control to turn on unit . The remote control 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 a water
flow over 2.4 L/min it compares the temperature at the Hot Water Thermistor to the set point
and begins the ignition process; the Combustion Fan starts first. Once the chamber has been
purged and the air proving has made the Electrode begins to spark to Earth. The Main
Solenoid Valve and Changeover Solenoid Valve 2 are opened and the Burner lights. The
Flame Rod will ensure proper burning before Changeover Solenoid Valve 1 will open.
Temperature Setting
With the Temperature Control Buttons on the controller the outlet temperature can be set from
37 - 60
℃
. When the temperature set point is above 50
℃
the High Temperature Indicator
glows. Temperature can not be set above 48
℃
while hot water is in use (flowing.) The unit will
continually monitor the outgoing temperature and can fully modulate the performance with the
Modulating Valve and the Servo Control .
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. The combustion fan will run on to post purge the chamber.
Schematic Diagram