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Mistral Boiler Error Codes 2021

Initial user checks

You are able to make some checks before calling out a service engineer.

  • Check you have enough fuel: check the sight gauge.
  • Check the fuel supply valves are open.
  • Check the external fire valve hasn't tripped: press the trip button.
  • Is the boiler electrical supply on?
  • Is the control panel high limit thermostat tripped? Check and reset if needed.
  • Burner control box locked out: check and press the lens.

Mistral boiler error codes

Fault Possible Cause
Burner does not start Air locks, supply lines blocked or tank vent blocked (no fuel getting into tank)
Restriction suspected / fuel supply fault Power supply to the boiler failed, burner control box locked out, burner motor fault or pump seized
Burner fault locks out after 15 seconds Photocell fault, restricted oil supply, combustion setting out of specification
No flame established (burner fault) Ignition failure, oil restricted or nozzle locked
Burner fault runs but continually pulsates Condensate trap blocked or flue system blocked
Lock-out Losing oil in the supply suction line or oil level in tank below minimum level
Burner running but smokes Tank topped with wrong fuel/ Air supply restricted/ Dust build up
Burner flame shuts down slowly Balanced flue system leaking/ Combustion leaks/ Suction line drawing air into fuel
Burner fails to reach working temperature Burner output restricted/ Low efficiency/ Control thermostat fault
Oil smells Oil leakage at connection
No hot water Circulating pump seized/ Programmer channel off
Flow and water temperature low Programmer for central heating or domestic hot water are off, debris build-up or low water supply pressure
No central heating or hot water Programmer channels are off, thermostat fault or turned off
Thermostat trips off Fault circulating pump
No central heating Spring fault or return valve not moving or operating properly – room stat error
No domestic hot water Spring fault, jammed in how water mode, flow switch blocked or faulty
Discharges on pressure relief valve Pressure vessel has lost charge, insufficient expansion volume

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Boiler Guide Team

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Boiler Guide Team

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