Common problems guide

The most common Ferroli Domi Compact problems

The faults most likely to send a Ferroli Domi Compact into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

This model is discontinued. Parts can be harder to source and expensive. If repair costs are mounting, a new A-rated boiler may be the smarter choice.
6 documented codes
6 most common
2 DIY-safe checks
4 engineer needed

The 6 most common faults

01
F37 High DIY-safe

Your boiler has detected that the water pressure inside the system is too low, so it has temporarily turned itself off to prevent any damage.

What to try first

Locate the filling loop (a silver flexi-hose with one or two valves) underneath your boiler.Open the valve(s) slowly to let water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Ensure both valves are fully closed again to stop the water flow.

Est. cost
£80-120
Parts
Pressure gauge, Filling loop, Pressure relief valve
Full guide for F37
02
5 (Flashing Light) High DIY-safe

Your boiler has stopped working because the water pressure inside the heating system has dropped too low.

What to try first

Locate the filling loop (a silver flexible hose with one or two valves) underneath the boiler.Open the valve(s) slowly to allow cold mains water into the system while watching the pressure gauge.Close the valve(s) tightly once the needle reaches 1.5 bar, then turn the boiler off and on again to clear the fault.

Est. cost
£0-£80
Parts
External filling loop, Pressure relief valve, Pressure sensor
Full guide for 5 (Flashing Light)
03
F1 High Engineer

Your boiler has stopped working because it failed to ignite the gas flame required to heat your water.

Est. cost
£120-250
Parts
Ignition electrode, Gas valve, PCB
Full guide for F1
04
F3 High Engineer

Your boiler has detected an issue with the airflow system or flue, causing it to shut down for safety reasons.

Est. cost
£120-250
Parts
Air pressure switch, Flue fan, Venturi
Full guide for F3
05
F50 Emergency Engineer

Your boiler has lost its connection to the gas control component, preventing it from safely starting up to provide heat or hot water.

Est. cost
£120-250
Parts
Gas valve wiring harness, Gas valve assembly, PCB
Full guide for F50
06
F5 Low Engineer

Your boiler has detected a temporary issue with the air vent or exhaust system and is pausing itself to stay safe, but it should restart on its own once the condition clears.

Est. cost
£100-250
Parts
Air pressure switch, Flue fan, Venturi
Full guide for F5
Parts most often replaced

on the Ferroli Domi Compact

Pressure gaugeFilling loopPressure relief valveExternal filling loopPressure sensorIgnition electrode

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Ferroli shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue
See the full 6-code list for the Ferroli Domi Compact

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →