Ideal
Ideal Water Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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F1
Water heater will not fire; the display shows F1 shortly after a call for hot water or heating.
Flame Detection Failure
F10
The display shows F10; the heater may run briefly then shut down, often with noisy boiling sounds.
Primary Flow Overheat (Thermal Runaway)
F11
The heater displays F11 and will not operate, often after wiring work or rodent damage.
NTC Sensor Circuit Error (General)
F12
The display shows F12, and there is no response to demand for hot water or heating.
User Interface / PCB Communication Fault
F13
The heater intermittently shuts down with F13, especially in very cold or hot ambient conditions.
Flue Gas Temperature Sensor Fault
F14
The display shows F14, and the heater may not respond to the thermostat or programmer.
External Control / Thermostat Input Fault
F15
The heater displays F15, often after a power cut or surge; the unit may be completely unresponsive.
Main PCB Fault
F16
The display shows F16, and the heater may cycle on and off rapidly or fail to modulate correctly.
Gas Valve Modulation / Combustion Control Fault
F17
The heater displays F17, often associated with low or fluctuating mains voltage.
Power Supply / Low Voltage Fault
F18
The display shows F18, and the heater may shut down during operation, sometimes with the fan still running.
Flue Fan Speed / Tachometer Fault
F19
The heater displays F19, often with erratic temperature control or overshooting the setpoint.
Flow Rate / DHW Modulation Fault
F2
Water heater locks out with F2; the fan starts, but ignition does not occur or stops quickly.
Ignition Failure
F20
The display shows F20, and the heater may not respond to hot water demand, but heating may still work (on combi-type water heater systems).
DHW Demand Recognition Fault
F3
The unit attempts to start, then shuts down with F3; the fan may run briefly.
Fan or Air Pressure Switch Fault
F4
The display shows F4, and the heater will not run; this may occur after overheating or poor circulation.
Primary Flow Thermistor Fault
F5
The heater locks out with F5, often after long operation or high demand.
Return Thermistor Fault
F6
The display shows F6; the heater may overheat quickly or shut down soon after starting.
Domestic Hot Water (DHW) Outlet Thermistor Fault
F7
The heater shows F7 and will not fire, often after a power surge or wiring disturbance.
Flow Switch / Flow Sensor Fault
F8
The display shows F8; the heater may start then shut down, or not start at all.
Gas Valve Control Fault
F9
The heater locks out with F9, often associated with overheating or poor circulation.
Overheat Thermostat / Safety Cut-out Trip
Symptom
Burning smell or signs of scorching around the Ideal water heater.
Overheating Electrical Component
Symptom
Condensate water backing up or dripping from the bottom of a condensing Ideal water heater.
Blocked Condensate Trap or Drain
Symptom
Hot water runs out quickly and takes a long time to reheat on an Ideal storage-type water heater.
Insufficient Storage or Reheat Performance
Symptom
Hot water temperature is too low even when the Ideal water heater is set to maximum.
Underheating / Reduced Output
Symptom
Ideal water heater runs continuously and overheats the stored water, even when demand is satisfied.
Thermostat or Control Stuck On
Symptom
No hot water at taps, heater does not start, no error code displayed.
No Demand / Flow Detection Failure
Symptom
Noisy vibration or humming from the water heater when running.
Mechanical Vibration / Resonance
Symptom
Rust-colored or dirty water from hot taps served by the Ideal water heater.
Corrosion / Sludge in System
Symptom
Water dripping from the pressure relief discharge pipe outside.
Pressure Relief Valve Discharge
Symptom
Water heater casing feels excessively hot to the touch during operation.
Insulation / Panel Overheating
Symptom
Water heater cycles on and off frequently when there is a small hot water demand.
Short Cycling on DHW
Symptom
Water heater does not start after being off for a long period (e.g., summer); no error code is displayed.
Seized Pump or Stuck Mechanical Components
Symptom
Water heater fan runs but the burner does not light; no error code is displayed.
No Ignition Without Fault Code
Symptom
Water heater makes loud banging or kettling noises during operation.
Kettling / Local Boiling in Heat Exchanger
Symptom
Water heater runs but hot water temperature fluctuates between hot and cold.
Inconsistent DHW Temperature Control
Symptom
Water heater trips the electrical breaker or RCD when it starts.
Electrical Short or Earth Leakage
Symptom
Water leaking from the bottom of the Ideal water heater casing.
Internal Water Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| F1 |
Water heater will not fire; the display shows F1 shortly after a call for hot water or heating.
|
Flame Detection Failure | View Details |
| F10 |
The display shows F10; the heater may run briefly then shut down, often with noisy boiling sounds.
|
Primary Flow Overheat (Thermal Runaway) | View Details |
| F11 |
The heater displays F11 and will not operate, often after wiring work or rodent damage.
|
NTC Sensor Circuit Error (General) | View Details |
| F12 |
The display shows F12, and there is no response to demand for hot water or heating.
|
User Interface / PCB Communication Fault | View Details |
| F13 |
The heater intermittently shuts down with F13, especially in very cold or hot ambient conditions.
|
Flue Gas Temperature Sensor Fault | View Details |
| F14 |
The display shows F14, and the heater may not respond to the thermostat or programmer.
|
External Control / Thermostat Input Fault | View Details |
| F15 |
The heater displays F15, often after a power cut or surge; the unit may be completely unresponsive.
|
Main PCB Fault | View Details |
| F16 |
The display shows F16, and the heater may cycle on and off rapidly or fail to modulate correctly.
|
Gas Valve Modulation / Combustion Control Fault | View Details |
| F17 |
The heater displays F17, often associated with low or fluctuating mains voltage.
|
Power Supply / Low Voltage Fault | View Details |
| F18 |
The display shows F18, and the heater may shut down during operation, sometimes with the fan still running.
|
Flue Fan Speed / Tachometer Fault | View Details |
| F19 |
The heater displays F19, often with erratic temperature control or overshooting the setpoint.
|
Flow Rate / DHW Modulation Fault | View Details |
| F2 |
Water heater locks out with F2; the fan starts, but ignition does not occur or stops quickly.
|
Ignition Failure | View Details |
| F20 |
The display shows F20, and the heater may not respond to hot water demand, but heating may still work (on combi-type water heater systems).
|
DHW Demand Recognition Fault | View Details |
| F3 |
The unit attempts to start, then shuts down with F3; the fan may run briefly.
|
Fan or Air Pressure Switch Fault | View Details |
| F4 |
The display shows F4, and the heater will not run; this may occur after overheating or poor circulation.
|
Primary Flow Thermistor Fault | View Details |
| F5 |
The heater locks out with F5, often after long operation or high demand.
|
Return Thermistor Fault | View Details |
| F6 |
The display shows F6; the heater may overheat quickly or shut down soon after starting.
|
Domestic Hot Water (DHW) Outlet Thermistor Fault | View Details |
| F7 |
The heater shows F7 and will not fire, often after a power surge or wiring disturbance.
|
Flow Switch / Flow Sensor Fault | View Details |
| F8 |
The display shows F8; the heater may start then shut down, or not start at all.
|
Gas Valve Control Fault | View Details |
| F9 |
The heater locks out with F9, often associated with overheating or poor circulation.
|
Overheat Thermostat / Safety Cut-out Trip | View Details |
| – |
Burning smell or signs of scorching around the Ideal water heater.
|
Overheating Electrical Component | View Details |
| – |
Condensate water backing up or dripping from the bottom of a condensing Ideal water heater.
|
Blocked Condensate Trap or Drain | View Details |
| – |
Hot water runs out quickly and takes a long time to reheat on an Ideal storage-type water heater.
|
Insufficient Storage or Reheat Performance | View Details |
| – |
Hot water temperature is too low even when the Ideal water heater is set to maximum.
|
Underheating / Reduced Output | View Details |
| – |
Ideal water heater runs continuously and overheats the stored water, even when demand is satisfied.
|
Thermostat or Control Stuck On | View Details |
| – |
No hot water at taps, heater does not start, no error code displayed.
|
No Demand / Flow Detection Failure | View Details |
| – |
Noisy vibration or humming from the water heater when running.
|
Mechanical Vibration / Resonance | View Details |
| – |
Rust-colored or dirty water from hot taps served by the Ideal water heater.
|
Corrosion / Sludge in System | View Details |
| – |
Water dripping from the pressure relief discharge pipe outside.
|
Pressure Relief Valve Discharge | View Details |
| – |
Water heater casing feels excessively hot to the touch during operation.
|
Insulation / Panel Overheating | View Details |
| – |
Water heater cycles on and off frequently when there is a small hot water demand.
|
Short Cycling on DHW | View Details |
| – |
Water heater does not start after being off for a long period (e.g., summer); no error code is displayed.
|
Seized Pump or Stuck Mechanical Components | View Details |
| – |
Water heater fan runs but the burner does not light; no error code is displayed.
|
No Ignition Without Fault Code | View Details |
| – |
Water heater makes loud banging or kettling noises during operation.
|
Kettling / Local Boiling in Heat Exchanger | View Details |
| – |
Water heater runs but hot water temperature fluctuates between hot and cold.
|
Inconsistent DHW Temperature Control | View Details |
| – |
Water heater trips the electrical breaker or RCD when it starts.
|
Electrical Short or Earth Leakage | View Details |
| – |
Water leaking from the bottom of the Ideal water heater casing.
|
Internal Water Leak | View Details |
No matching codes found
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