Rinnai INFINITY REU-3203W, Service Manual

Page: 19 / 64

Infinity REU-3203W - 14 - ©Rinnai
9. Operation Principles
Hot Water Operation
1. Ignition
• Activate controllers (if fitted) and open the hot water tap (for full details regarding operation of
controllers refer to the ‘How To Use Your Water Heater’ booklet).
• When water flows through the unit, the water flow sensor rotates and sends an electrical ‘pulse’
signal to the Printed Circuit Board (PCB). This signal is proportional to the water flow rate.
• The PCB sends electrical current to the combustion fan motor causing it to turn. The fan motor
sends an electrical pulse signal to the PCB. If fan rotation is OK, the main solenoid and
changeover solenoid valves open as required, the spark generator activates and the spark
electrode ignites the burner.
2. Water Temperature / Flow Control / Volume Control
• The PCB will automatically control operation of the internal components to achieve the
programmed temperature. When a high temperature rise is required, the PCB may cause the
Water Flow Servo to close partially resulting in a lower flow rate to achieve the programmed
temperature. This is a necessary operational feature of the unit.
• When operating in ‘Bath Fill’ mode, the signal from the water flow sensor is also used by the
PCB to compute the volume of water that has been passed through the unit at any instant whilst
the bath is filling.
3. Shut Down
• When operating in ‘Bath Fill’ mode, the PCB causes the Water Flow Servo to close when the
programmed Bath Fill volume has passed through the unit. Alternatively, flow is stopped when
the user closes the hot water tap.
• When water flow stops, the water flow sensor stops rotating and the pulse signal to the PCB
stops. The PCB then causes the main solenoid and solenoid valves to close and the burner is
extinguished. The combustion fan will continue to operate for some time to purge the
combustion chamber.