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.
5 documented codes
5 most common
3 DIY-safe checks
2 engineer needed

The 5 most common faults

01
Low water pressure High DIY-safe

Your boiler has detected that there is not enough water inside the heating system to allow it to operate safely.

What to try first

Locate the two small taps (filling loop) connected to the pipes underneath your boiler.Open the taps slowly to let fresh water enter the system until the needle on the pressure gauge reaches approximately 1.5 bar.Close both taps tightly and check the boiler display to see if the error light has cleared.

Est. cost
£80-120
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for Low water pressure
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
LED 5 (Flashing light) High DIY-safe

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

What to try first

Locate the external filling loop, which is usually a metal braided hose underneath the boiler.Open the small valve on the filling loop to allow water to enter the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the valve firmly and ensure the boiler resets itself.

Est. cost
£80-120
Parts
Filling loop, Pressure relief valve, Pressure gauge
Full guide for LED 5 (Flashing light)
04
Red lockout light High Engineer

Your boiler has detected an issue and stopped working as a safety precaution, likely because the fuel supply is interrupted or the internal pipe for water drainage is blocked.

Est. cost
£100-250
Parts
Ignition electrode, Gas valve, Condensate trap
Full guide for Red lockout light
05
Boiler lock out High Engineer

Your boiler has stopped working for safety reasons and needs a manual reset after investigating potential blockages or gas supply issues.

Est. cost
£120-250
Parts
Condensate trap, Ignition electrode, Flame sensor
Full guide for Boiler lock out
Parts most often replaced

on the Ferroli F 30 B

Filling loopPressure relief valvePressure sensorPressure gaugeIgnition electrodeGas valve

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 F 30 B

Related guides

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