Rinnai Boilers Error Codes

10

Boiler shuts down and displays error 10; unit may attempt to start but stops within seconds, sometimes with fan noise briefly heard.

Air Supply or Exhaust Blockage

11

Boiler displays error 11 and will not ignite; you may hear clicking from the igniter but no flame is established.

Ignition Failure

12

Boiler starts to ignite, flame appears briefly, then shuts down and shows error 12.

Flame Loss During Operation

14

Boiler locks out with error 14; unit may overheat and shut down shortly after firing.

Thermal Fuse or Overheat Cutoff Trip

16

Boiler displays error 16 and shuts down after running for a short period, often at high demand.

Outlet Water Over-Temperature

19

Boiler intermittently shuts down with error 19, often during modulation or when demand changes.

Electrical Grounding or Power Supply Fault

25

Boiler stops and shows error 25; condensate may be visible around the unit or in the base tray.

Condensate Drain Blockage

30

Boiler displays error 30 and will not operate; may be accompanied by a smell of combustion gases or signs of overheating inside the casing.

Flame Rod or Combustion Safety Fault

31

Boiler shows error 31; unit may not start or may shut down shortly after starting.

Inlet Thermistor Fault

32

Boiler displays error 32 and will not operate or modulates incorrectly.

Outlet Thermistor Fault

33

Boiler shows error 33; unit may lock out immediately on a call for heat or hot water.

Heat Exchanger Thermistor Fault

34

Boiler intermittently shuts down with error 34, often in windy conditions or when venting is marginal.

Combustion Air or Flue Temperature Sensor Fault

35

Boiler shows error 35 and will not run; may occur after electrical storms or power surges.

Abnormal Flame Detection Signal

41

Boiler displays error 41 and will not operate; may occur after wiring work or component replacement.

Flow Sensor Fault

51

Boiler shows error 51; fan may not start or may run erratically.

Combustion Fan Motor Fault

52

Boiler locks out with error 52; fan may run but ignition does not proceed correctly.

Modulating Gas Valve or Combustion Control Fault

61

Boiler displays error 61; fan may not respond to speed commands or may run at a fixed speed.

Combustion Fan Speed Feedback Fault

65

Boiler shows error 65; domestic hot water may not be recognized or may not start.

Water Flow Control or Bypass Valve Fault

70

Boiler displays error 70 and will not operate.

Main Control PCB Fault

71

Boiler shows error 71; may occur after component replacement or wiring changes.

Gas Valve Circuit Fault

72

Boiler intermittently locks out with error 72, often during ignition attempts.

Flame Sensing Circuit Abnormality

73

Boiler shows error 73; may occur after replacing the control board or changing settings.

Parameter Setting or Communication Error

79

Boiler displays error 79; may be associated with abnormal temperature readings or erratic operation.

Circulation Thermistor or System Sensor Fault

90

Boiler locks out with error 90; may occur during high fire or under heavy load.

Abnormal Combustion or Gas Combustion Fault

91

Boiler shows error 91 and will not ignite; may be associated with low gas supply conditions.

Gas Supply or Gas Valve Fault

92

Boiler intermittently displays error 92; may occur during modulation or when demand changes rapidly.

Combustion Feedback or Fan/Gas Valve Coordination Fault

99

Boiler locks out with error 99; may be accompanied by signs of overheating or poor combustion.

Severe Combustion or Overheat Fault

Symptom

Boiler and nearby pipework vibrate excessively during operation; you may hear humming or buzzing.

Mechanical Vibration / Resonance

Symptom

Boiler cycles on and off frequently with short run times, even when there is a continuous demand for heat.

Short Cycling

Symptom

Boiler display is on but unresponsive; buttons do not work or respond erratically.

Control Panel / User Interface Fault

Symptom

Boiler does not start at all; no display, no lights, and no response to controls.

No Power / Dead Boiler

Symptom

Boiler fails to respond to room thermostat or external control signals; heating does not start even though there is demand.

Control Signal / Thermostat Communication Fault

Symptom

Boiler frequently loses pressure; pressure gauge drops below the minimum and the boiler shuts down.

System Water Loss / Pressure Loss

Symptom

Boiler leaks water from the bottom or from internal components; puddles may form under the unit.

Internal Water Leak

Symptom

Boiler makes loud banging or knocking noises when starting or stopping, sometimes called kettling.

Heat Exchanger Kettling / Localized Boiling

Symptom

Boiler or flue area smells strongly of exhaust or combustion fumes inside the property.

Flue Gas Spillage / Venting Failure

Symptom

Boiler or flue emits unusual rumbling, roaring, or whistling noises during operation.

Abnormal Combustion Noise

Symptom

Boiler or surrounding area smells of gas, especially near the gas valve or pipe connections.

Gas Leak

Symptom

Boiler pressure rises rapidly when heating is on and may discharge water from the pressure relief valve.

Over-Pressurization / Expansion Fault

Symptom

Boiler runs but radiators or underfloor heating remain cold; domestic hot water may still work.

No Central Heating Output

Symptom

Boiler shuts down intermittently without showing an error code; may restart on its own later.

Intermittent Lockout / Nuisance Shutdown

Symptom

Domestic hot water is not hot enough, even when the boiler is set to a high temperature.

Insufficient Domestic Hot Water Temperature

Symptom

Domestic hot water temperature fluctuates between hot and cold during use.

Inconsistent Domestic Hot Water Temperature