Alpha
Alpha 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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E01
Water heater will not ignite; display shows E01 shortly after a hot water tap is opened.
Ignition Failure
E02
Water heater attempts to ignite but shuts down with E02; burner lights briefly then goes out.
Flame Detection Failure
E03
Unit displays E03 and shuts down; exhaust fan may run briefly, no ignition sequence starts.
Exhaust Fan / Combustion Blower Failure
E04
Display shows E04 and the unit will not fire; occurs immediately when a hot water tap is opened.
Air Pressure Switch / Draft Proving Failure
E05
Water heater locks out with E05; burner shuts down during operation, often after running for several minutes.
Overheat / High Limit Trip
E06
Display shows E06 and the unit will not operate; may occur intermittently with fluctuating water temperature.
Inlet Temperature Sensor Fault
E07
Unit displays E07 and shuts down; may occur during long draws of hot water.
Outlet Temperature Sensor Fault
E08
Display shows E08; water heater does not start and fan may not run.
Fan Speed / Hall Sensor Error
E09
Unit shows E09 and shuts down; may be accompanied by gurgling sounds in the vent or condensate lines.
Condensate Drain Blockage
E10
Display shows E10; unit does not respond to hot water demand or buttons.
Communication Error Between User Interface and Main Control Board
E11
Unit shows E11 and will not ignite; often occurs after recent installation or gas work.
Gas Supply / Gas Valve Error
E12
Display shows E12; water temperature fluctuates and unit may short-cycle.
Flow Sensor / Turbine Error
E13
Unit displays E13 and shuts down; may be associated with very high exhaust temperatures.
Flue Gas Overtemperature
E14
Display shows E14; unit may not respond to thermostat or temperature setting changes.
Thermostat / Setpoint Control Error
E15
Unit shows E15; may occur after a power surge or lightning event.
Internal Control Board Error
E16
Display shows E16; unit may operate but with erratic fan or ignition behavior.
Low Voltage / Power Supply Error
E17
Unit displays E17; hot water output is limited or unit cycles off under high demand.
Flow Rate Exceeded / Overload Protection
E18
Display shows E18; unit may shut down during operation, especially in cold weather.
Freeze Protection / Low Temperature Fault
E19
Unit shows E19; burner shuts down and may not restart until power is cycled.
Flame Loss During Operation
E20
Display shows E20; unit may not start or may shut down unexpectedly.
Safety Chain / Limit Circuit Open
Symptom
Alpha tankless water heater cycles on and off rapidly with small hot water draws.
Short Cycling on Low Flow
Symptom
Burner produces yellow, lazy flames or soot around the burner compartment.
Incomplete Combustion / Sooting
Symptom
Condensation or water dripping from vent pipe or around flue hood.
Condensation / Venting Issue
Symptom
Discolored (rusty or brown) hot water from faucets; cold water is clear.
Corrosion / Rust Contamination
Symptom
External surfaces of the water heater feel excessively hot to the touch.
Insulation / Jacket Overheating
Symptom
Hot water runs out quickly; starts hot but becomes lukewarm or cold within a short time.
Reduced Hot Water Capacity
Symptom
Loud banging or hammering noise in pipes when hot water is used.
Water Hammer / Thermal Expansion Noise
Symptom
No hot water at any faucet; water remains cold even after running for several minutes; no error code displayed.
Complete No-Heat Condition
Symptom
Pilot light will not stay lit on standing-pilot Alpha gas water heater (if applicable).
Pilot Flame Holding Failure
Symptom
Rotten egg or sulfur smell from hot water only.
Odor from Bacterial Growth / Anode Reaction
Symptom
Temperature and pressure (T&P) relief valve drips or discharges water periodically.
T&P Valve Discharge / Overpressure or Overtemperature
Symptom
Water heater does not start heating after power outage; display may be blank.
No Power / Control Not Initializing
Symptom
Water heater leaks from the bottom of the tank or around the base; no error code.
Tank Leakage / Internal Corrosion
Symptom
Water heater leaks from the top around piping connections.
Top Connection Leak
Symptom
Water heater makes popping or rumbling noises during heating cycles.
Sediment Boiling / Scale Buildup
Symptom
Water heater trips the circuit breaker or blows fuses when it tries to heat.
Electrical Short / Overcurrent
Symptom
Water is too hot; scalding at faucets even at low mixing valve settings.
Overheating / Thermostat Runaway
Symptom
Water is warm but not hot enough; temperature lower than setpoint across all fixtures.
Insufficient Heating / Under-Temperature
Symptom
Water temperature fluctuates between hot and cold during a shower.
Temperature Fluctuation / Hunting
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Water heater will not ignite; display shows E01 shortly after a hot water tap is opened.
|
Ignition Failure | View Details |
| E02 |
Water heater attempts to ignite but shuts down with E02; burner lights briefly then goes out.
|
Flame Detection Failure | View Details |
| E03 |
Unit displays E03 and shuts down; exhaust fan may run briefly, no ignition sequence starts.
|
Exhaust Fan / Combustion Blower Failure | View Details |
| E04 |
Display shows E04 and the unit will not fire; occurs immediately when a hot water tap is opened.
|
Air Pressure Switch / Draft Proving Failure | View Details |
| E05 |
Water heater locks out with E05; burner shuts down during operation, often after running for several minutes.
|
Overheat / High Limit Trip | View Details |
| E06 |
Display shows E06 and the unit will not operate; may occur intermittently with fluctuating water temperature.
|
Inlet Temperature Sensor Fault | View Details |
| E07 |
Unit displays E07 and shuts down; may occur during long draws of hot water.
|
Outlet Temperature Sensor Fault | View Details |
| E08 |
Display shows E08; water heater does not start and fan may not run.
|
Fan Speed / Hall Sensor Error | View Details |
| E09 |
Unit shows E09 and shuts down; may be accompanied by gurgling sounds in the vent or condensate lines.
|
Condensate Drain Blockage | View Details |
| E10 |
Display shows E10; unit does not respond to hot water demand or buttons.
|
Communication Error Between User Interface and Main Control Board | View Details |
| E11 |
Unit shows E11 and will not ignite; often occurs after recent installation or gas work.
|
Gas Supply / Gas Valve Error | View Details |
| E12 |
Display shows E12; water temperature fluctuates and unit may short-cycle.
|
Flow Sensor / Turbine Error | View Details |
| E13 |
Unit displays E13 and shuts down; may be associated with very high exhaust temperatures.
|
Flue Gas Overtemperature | View Details |
| E14 |
Display shows E14; unit may not respond to thermostat or temperature setting changes.
|
Thermostat / Setpoint Control Error | View Details |
| E15 |
Unit shows E15; may occur after a power surge or lightning event.
|
Internal Control Board Error | View Details |
| E16 |
Display shows E16; unit may operate but with erratic fan or ignition behavior.
|
Low Voltage / Power Supply Error | View Details |
| E17 |
Unit displays E17; hot water output is limited or unit cycles off under high demand.
|
Flow Rate Exceeded / Overload Protection | View Details |
| E18 |
Display shows E18; unit may shut down during operation, especially in cold weather.
|
Freeze Protection / Low Temperature Fault | View Details |
| E19 |
Unit shows E19; burner shuts down and may not restart until power is cycled.
|
Flame Loss During Operation | View Details |
| E20 |
Display shows E20; unit may not start or may shut down unexpectedly.
|
Safety Chain / Limit Circuit Open | View Details |
| – |
Alpha tankless water heater cycles on and off rapidly with small hot water draws.
|
Short Cycling on Low Flow | View Details |
| – |
Burner produces yellow, lazy flames or soot around the burner compartment.
|
Incomplete Combustion / Sooting | View Details |
| – |
Condensation or water dripping from vent pipe or around flue hood.
|
Condensation / Venting Issue | View Details |
| – |
Discolored (rusty or brown) hot water from faucets; cold water is clear.
|
Corrosion / Rust Contamination | View Details |
| – |
External surfaces of the water heater feel excessively hot to the touch.
|
Insulation / Jacket Overheating | View Details |
| – |
Hot water runs out quickly; starts hot but becomes lukewarm or cold within a short time.
|
Reduced Hot Water Capacity | View Details |
| – |
Loud banging or hammering noise in pipes when hot water is used.
|
Water Hammer / Thermal Expansion Noise | View Details |
| – |
No hot water at any faucet; water remains cold even after running for several minutes; no error code displayed.
|
Complete No-Heat Condition | View Details |
| – |
Pilot light will not stay lit on standing-pilot Alpha gas water heater (if applicable).
|
Pilot Flame Holding Failure | View Details |
| – |
Rotten egg or sulfur smell from hot water only.
|
Odor from Bacterial Growth / Anode Reaction | View Details |
| – |
Temperature and pressure (T&P) relief valve drips or discharges water periodically.
|
T&P Valve Discharge / Overpressure or Overtemperature | View Details |
| – |
Water heater does not start heating after power outage; display may be blank.
|
No Power / Control Not Initializing | View Details |
| – |
Water heater leaks from the bottom of the tank or around the base; no error code.
|
Tank Leakage / Internal Corrosion | View Details |
| – |
Water heater leaks from the top around piping connections.
|
Top Connection Leak | View Details |
| – |
Water heater makes popping or rumbling noises during heating cycles.
|
Sediment Boiling / Scale Buildup | View Details |
| – |
Water heater trips the circuit breaker or blows fuses when it tries to heat.
|
Electrical Short / Overcurrent | View Details |
| – |
Water is too hot; scalding at faucets even at low mixing valve settings.
|
Overheating / Thermostat Runaway | View Details |
| – |
Water is warm but not hot enough; temperature lower than setpoint across all fixtures.
|
Insufficient Heating / Under-Temperature | View Details |
| – |
Water temperature fluctuates between hot and cold during a shower.
|
Temperature Fluctuation / Hunting | View Details |
No matching codes found
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