Raypak
Raypak Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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A01
Boiler will not ignite; display shows A01 lockout, fan may run briefly then stop, no flame established.
Ignition Failure / Flame Not Detected
A02
Boiler lights briefly then shuts down; display shows A02, multiple short ignition attempts before lockout.
Flame Loss During Operation
A03
The boiler display shows A03 and the unit will not start; the fan may not run or runs briefly then stops.
Air Pressure Switch / Combustion Air Proving Fault
A04
The boiler locks out with A04; the unit may start then shut down due to high temperature, or may not start at all.
High Limit / Safety Temperature Lockout
A05
The boiler display shows A05; the unit may not fire and indicates a low water or flow fault.
Low Water Flow / Flow Switch Open
A06
The boiler shows A06; the ignition sequence may not start, or the control indicates low gas pressure.
Low Gas Pressure / Gas Supply Fault
A07
The boiler display shows A07; the unit may shut down shortly after ignition, often associated with flue or vent temperature issues.
Flue Temperature High / Flue Sensor Fault
A11
The boiler shows A11; the unit may not respond to a thermostat or BMS call for heat.
External Control / Thermostat Input Fault
A21
The boiler display shows A21; the unit may shut down unexpectedly during operation.
Outlet Water Temperature Sensor Fault
A22
The boiler shows A22; the unit may not modulate correctly or may shut down due to a temperature error.
Inlet Water Temperature Sensor Fault
A23
The boiler display shows A23; the unit may lock out or operate erratically.
Outdoor Temperature Sensor Fault (if equipped)
A41
The boiler shows A41; the fan may not start or may run at an incorrect speed.
Combustion Fan / Blower Fault
A51
Boiler display shows A51; unit may not fire and indicates a low water level or safety lockout.
Low Water Cutoff (LWCO) Fault
A61
Boiler shows A61; unit may not respond to pump commands or may shut down due to a pump fault.
System Pump / Boiler Pump Fault
A71
Boiler display shows A71; unit may lock out due to a safety chain fault.
Safety Circuit Open (Limit String Fault)
A81
Boiler shows A81; control indicates an internal fault or EEPROM error.
Control Board Internal Error
E01
Boiler display shows E01; ignition lockout with no flame detected.
Ignition Lockout (No Flame)
E02
Boiler shows E02; flame detected when there should be none (false flame signal).
False Flame / Flame Detection Fault
E03
Boiler display shows E03; fan or air proving fault, similar to A03 on some models.
Air Pressure / Fan Proving Error
E04
Boiler shows E04; high limit or temperature sensor error on some Raypak models.
High Limit / Temperature Sensor Error
E05
Boiler display shows E05; outlet temperature sensor fault on some digital Raypak boilers.
Outlet Sensor Open/Short
E06
Boiler shows E06; inlet temperature sensor fault on some models.
Inlet Sensor Open/Short
E09
Boiler display shows E09: flue sensor fault on some Raypak digital boilers.
Flue Temperature Sensor Open/Short
E12
Boiler shows E12: communication error between display and main control on some Raypak models.
Control Communication Fault
Symptom
Boiler display flickers or resets randomly during operation.
Intermittent Power / Control Voltage Issue
Symptom
Boiler display is on, but there is no response to a call for heat; status shows 'Standby' even when heat is needed.
No Call for Heat / Control Interlock
Symptom
Boiler emits exhaust smell or flue gas odor in mechanical room.
Flue Gas Spillage / Venting Problem
Symptom
Boiler fan runs, but burners do not light; no error code is displayed.
No Ignition Without Fault Code
Symptom
Boiler frequently trips the pressure relief valve; water discharges from relief outlet.
Overpressure / Relief Valve Discharge
Symptom
Boiler leaking water from bottom of cabinet or around piping connections.
System or Internal Water Leak
Symptom
Boiler makes loud banging or knocking noises (kettling) during operation.
Kettling / Boiling in Heat Exchanger
Symptom
Boiler runs but does not reach the set temperature; supply water is lukewarm.
Insufficient Heating Output
Symptom
Boiler short cycles: frequently turns on and off with very short run times.
Short Cycling / Control or System Imbalance
Symptom
Boiler starts, then shuts down after a few seconds; it may retry several times without displaying a code.
Flame Proving Intermittent / Nuisance Lockout
Symptom
Boiler will not start at all: no display, no lights, completely dead.
No Power / Electrical Supply Failure
Symptom
The boiler control shows normal operation, but the building does not heat adequately during very cold weather.
Undersizing or Outdoor Reset Misconfiguration
Symptom
The boiler cycles on and off due to low flow; piping near the boiler is very hot, but distant zones are cold.
Flow Imbalance / Primary-Secondary Piping Issue
Symptom
The boiler is excessively noisy with a rumbling or roaring burner sound.
Combustion Noise / Improper Combustion
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A01 |
Boiler will not ignite; display shows A01 lockout, fan may run briefly then stop, no flame established.
|
Ignition Failure / Flame Not Detected | View Details |
| A02 |
Boiler lights briefly then shuts down; display shows A02, multiple short ignition attempts before lockout.
|
Flame Loss During Operation | View Details |
| A03 |
The boiler display shows A03 and the unit will not start; the fan may not run or runs briefly then stops.
|
Air Pressure Switch / Combustion Air Proving Fault | View Details |
| A04 |
The boiler locks out with A04; the unit may start then shut down due to high temperature, or may not start at all.
|
High Limit / Safety Temperature Lockout | View Details |
| A05 |
The boiler display shows A05; the unit may not fire and indicates a low water or flow fault.
|
Low Water Flow / Flow Switch Open | View Details |
| A06 |
The boiler shows A06; the ignition sequence may not start, or the control indicates low gas pressure.
|
Low Gas Pressure / Gas Supply Fault | View Details |
| A07 |
The boiler display shows A07; the unit may shut down shortly after ignition, often associated with flue or vent temperature issues.
|
Flue Temperature High / Flue Sensor Fault | View Details |
| A11 |
The boiler shows A11; the unit may not respond to a thermostat or BMS call for heat.
|
External Control / Thermostat Input Fault | View Details |
| A21 |
The boiler display shows A21; the unit may shut down unexpectedly during operation.
|
Outlet Water Temperature Sensor Fault | View Details |
| A22 |
The boiler shows A22; the unit may not modulate correctly or may shut down due to a temperature error.
|
Inlet Water Temperature Sensor Fault | View Details |
| A23 |
The boiler display shows A23; the unit may lock out or operate erratically.
|
Outdoor Temperature Sensor Fault (if equipped) | View Details |
| A41 |
The boiler shows A41; the fan may not start or may run at an incorrect speed.
|
Combustion Fan / Blower Fault | View Details |
| A51 |
Boiler display shows A51; unit may not fire and indicates a low water level or safety lockout.
|
Low Water Cutoff (LWCO) Fault | View Details |
| A61 |
Boiler shows A61; unit may not respond to pump commands or may shut down due to a pump fault.
|
System Pump / Boiler Pump Fault | View Details |
| A71 |
Boiler display shows A71; unit may lock out due to a safety chain fault.
|
Safety Circuit Open (Limit String Fault) | View Details |
| A81 |
Boiler shows A81; control indicates an internal fault or EEPROM error.
|
Control Board Internal Error | View Details |
| E01 |
Boiler display shows E01; ignition lockout with no flame detected.
|
Ignition Lockout (No Flame) | View Details |
| E02 |
Boiler shows E02; flame detected when there should be none (false flame signal).
|
False Flame / Flame Detection Fault | View Details |
| E03 |
Boiler display shows E03; fan or air proving fault, similar to A03 on some models.
|
Air Pressure / Fan Proving Error | View Details |
| E04 |
Boiler shows E04; high limit or temperature sensor error on some Raypak models.
|
High Limit / Temperature Sensor Error | View Details |
| E05 |
Boiler display shows E05; outlet temperature sensor fault on some digital Raypak boilers.
|
Outlet Sensor Open/Short | View Details |
| E06 |
Boiler shows E06; inlet temperature sensor fault on some models.
|
Inlet Sensor Open/Short | View Details |
| E09 |
Boiler display shows E09: flue sensor fault on some Raypak digital boilers.
|
Flue Temperature Sensor Open/Short | View Details |
| E12 |
Boiler shows E12: communication error between display and main control on some Raypak models.
|
Control Communication Fault | View Details |
| – |
Boiler display flickers or resets randomly during operation.
|
Intermittent Power / Control Voltage Issue | View Details |
| – |
Boiler display is on, but there is no response to a call for heat; status shows 'Standby' even when heat is needed.
|
No Call for Heat / Control Interlock | View Details |
| – |
Boiler emits exhaust smell or flue gas odor in mechanical room.
|
Flue Gas Spillage / Venting Problem | View Details |
| – |
Boiler fan runs, but burners do not light; no error code is displayed.
|
No Ignition Without Fault Code | View Details |
| – |
Boiler frequently trips the pressure relief valve; water discharges from relief outlet.
|
Overpressure / Relief Valve Discharge | View Details |
| – |
Boiler leaking water from bottom of cabinet or around piping connections.
|
System or Internal Water Leak | View Details |
| – |
Boiler makes loud banging or knocking noises (kettling) during operation.
|
Kettling / Boiling in Heat Exchanger | View Details |
| – |
Boiler runs but does not reach the set temperature; supply water is lukewarm.
|
Insufficient Heating Output | View Details |
| – |
Boiler short cycles: frequently turns on and off with very short run times.
|
Short Cycling / Control or System Imbalance | View Details |
| – |
Boiler starts, then shuts down after a few seconds; it may retry several times without displaying a code.
|
Flame Proving Intermittent / Nuisance Lockout | View Details |
| – |
Boiler will not start at all: no display, no lights, completely dead.
|
No Power / Electrical Supply Failure | View Details |
| – |
The boiler control shows normal operation, but the building does not heat adequately during very cold weather.
|
Undersizing or Outdoor Reset Misconfiguration | View Details |
| – |
The boiler cycles on and off due to low flow; piping near the boiler is very hot, but distant zones are cold.
|
Flow Imbalance / Primary-Secondary Piping Issue | View Details |
| – |
The boiler is excessively noisy with a rumbling or roaring burner sound.
|
Combustion Noise / Improper Combustion | View Details |
No matching codes found
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