Common problems guide

The most common Ferroli F 30 B problems

The faults most likely to send a Ferroli F 30 B 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.
19 documented codes
6 most common
3 DIY-safe checks
3 engineer needed

The 6 most common faults

01
F37 High DIY-safe

Your boiler has stopped working because the water pressure inside the system is currently too low to operate safely.

What to try first

Locate the external filling loop, which is usually a flexible silver hose connected to two valves beneath the boiler.Open the valves slowly to allow cold mains water to enter the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Fully close the valves and ensure they are tight to prevent over-pressurisation.

Est. cost
£80-£150
Parts
Pressure relief valve, Pressure sensor, Expansion vessel
Full guide for F37
02
5 (Flashing Light) High DIY-safe

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

What to try first

Locate the filling loop (a flexible metal hose) underneath the boiler.Open the small valve or tap on the filling loop to allow water to enter the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (usually 1.0 to 1.5 bar).Close the valve tightly and check that the fault light has cleared.

Est. cost
£0-£80
Parts
Filling loop, Pressure relief valve, Pressure gauge
Full guide for 5 (Flashing Light)
03
LED5 Flashing High DIY-safe

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

What to try first

Locate the external filling loop, which is a silver braided flexible hose connected between two pipes under your boiler.Open the small black or metal valve(s) on the loop to allow water to enter the system while watching the pressure gauge on the front of the boiler.When the needle reaches 1.5 bar on the gauge, close the valve(s) tightly to stop the flow of water.

Est. cost
£80-120
Parts
Filling loop, Pressure gauge, Pressure relief valve
Full guide for LED5 Flashing
04
F1 High Engineer

Your boiler has detected that it cannot start the flame needed to heat your water or home.

Est. cost
£120-250
Parts
Ignition electrode, Gas valve, Ignition transformer
Full guide for F1
05
F2 High Engineer

Your boiler has stopped because it cannot maintain a stable flame, meaning your heating and hot water have turned off for safety.

Est. cost
£120-250
Parts
Ionisation electrode, Gas valve, PCB
Full guide for F2
06
F3 High Engineer

Your boiler has detected that it is getting too hot and has automatically shut down to prevent damage or dangerous overheating.

Est. cost
£120-250
Parts
High limit thermostat, Central heating pump, Primary heat exchanger
Full guide for F3
Parts most often replaced

on the Ferroli F 30 B

Pressure relief valvePressure sensorExpansion vesselFilling loopPressure gaugeIgnition 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 19-code list for the Ferroli F 30 B

Related guides

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