Common problems guide

The most common Ferroli Optimax HE 31 C problems

The faults most likely to send a Ferroli Optimax HE 31 C 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.
5 documented codes
5 most common
1 DIY-safe checks
4 engineer needed

The 5 most common faults

01
Low system pressure High DIY-safe

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

What to try first

Locate the external filling loop, usually a small braided metal hose connecting two pipes under the boilerOpen the valves at both ends of the hose to allow mains water to enter the system while watching the pressure gaugeClose both valves firmly once the needle sits between 1 and 1.5 barReset the boiler using the reset button on the control panel

Parts
Filling loop, Pressure relief valve, Expansion vessel
Full guide for Low system pressure
02
No burner ignition High Engineer

Your boiler is failing to light the flame needed to heat your water and home.

Est. cost
£120-250
Parts
Ignition electrode, Gas valve, PCB
Full guide for No burner ignition
03
F07 High Engineer

Your boiler has detected an issue with the airflow system, which prevents it from firing up safely to provide heating or hot water.

Est. cost
£150-350
Parts
Fan unit, Air pressure switch, Flue seals
Full guide for F07
04
F24 High Engineer

Your boiler is struggling to clear exhaust gases because the fan component, which helps vent the system, is not receiving power or is failing to start.

Est. cost
£180-350
Parts
Fan assembly, Wiring harness, PCB (Printed Circuit Board)
Full guide for F24
05
A16 High Engineer

Your boiler is unable to safely control the flow of gas required to light the burner, so it has shut down to prevent any unsafe operation.

Est. cost
£200-350
Parts
Gas valve, PCB
Full guide for A16
Parts most often replaced

on the Ferroli Optimax HE 31 C

Filling loopPressure relief valveExpansion vesselIgnition electrodeGas valvePCB

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 5-code list for the Ferroli Optimax HE 31 C

Related guides

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