Operation Principles - Rinnai REU-K2430WG Service Manual

8. Operation Principles

Hot Water Operation
1) Ignition
• Activate controllers (if fitted) and open the hot water tap (for full details regarding operation of water controllers
refer to the 'Operation / Installation manual supplied with water heater).
• 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 and Flow
• 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 Sensor 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 Sensor 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.
REU-K2430WG-AK (Envirosmart ) - 12 - Issue 1 - 16/12/09 ©Rinnai