Grant Euroflame fault 5
Boiler operating on overheat thermostat
Oil boilerWhat it means
Boiler trips on the overheat thermostat, indicating excessive water temperature, often due to lack of circulation.
Likely causes
- Faulty boiler thermostat
- No circulation
- Faulty circulating pump
- Air lock in system
- Motor/pump fault
- Electrode/ignition fault
- Control box fault
- Oil pump fault
- Solenoid valve/coil fault
- Nozzle/fuel contamination
- Combustion air/head setting fault
- Photocell fault
- Balanced flue recirculation
- Boiler or flue blockage
- Incorrect diffuser position causing poor flame pattern or combustion issues
- Contaminated oil pump filter restricting fuel flow
- Air lock in pump
- Pump running dry
Where to start
- Check circulating pump
- Check for air lock
- Burner motor runs? NO -> Check L & N to control box -> if fail check boiler controls
The full answer, free
- 22 more checks in order
- The readings and component tests from the manual
- How to put it right, step by step
- The manual page for this fault (page 43), right under the answer
Safety: Isolate oil and power before you touch the burner. Do a combustion test after any burner adjustment or part change. OFTEC (or equivalent) work only.
From the Grant manual for the Euroflame. Check the model on the data plate before you order parts.