Common problems guide

The most common Chaffoteaux Britony II 40FF problems

The faults most likely to send a Chaffoteaux Britony II 40FF 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.
37 documented codes
6 most common
3 DIY-safe checks
3 engineer needed

The 6 most common faults

01
8.7 High DIY-safe

Your boiler has detected that the water temperature is too low for it to operate correctly, which usually means the water is not circulating properly or a sensor is faulty.

What to try first

Check that your boiler pressure is between 1 and 1.5 bar on the gauge.Ensure all radiator valves are fully open.Restart the boiler using the reset button to see if the error clears.

Est. cost
£90-180
Parts
Temperature Sensor (NTC Thermistor), Circulation Pump, Heat Exchanger
Full guide for 8.7
02
8.12 High DIY-safe

Your boiler has detected that the water pressure is too low for it to operate safely and effectively.

What to try first

Locate the filling loop (the silver braided hose) underneath or near the boiler.Slowly open the valve(s) until you hear water flowing and watch the pressure gauge.Close the valves tightly once the pressure gauge reaches 1.5 bar.

Est. cost
£0-120
Parts
Filling loop, Expansion vessel, Pressure sensor
Full guide for 8.12
03
8.15 High DIY-safe

Your boiler has detected that the water pressure is too low for it to operate safely and has shut down.

What to try first

Locate the filling loop (a silver flexible hose) underneath or near the boilerSlowly open the small valves on the filling loop until you hear water flowingWatch the pressure gauge and close the valves once it reaches between 1.0 and 1.5 bar

Est. cost
£0-120
Parts
Filling loop, Pressure sensor, Expansion vessel
Full guide for 8.15
04
WATER TEMPERATURE High Engineer

Your boiler is struggling to heat your hot water properly, usually because the water is flowing through it too quickly for it to warm up or because the gas supply is restricted.

Est. cost
£120-250
Parts
Water governor, Venturi, Flow regulator
Full guide for WATER TEMPERATURE
05
HEATING BODY NOISE High Engineer

Your boiler is making loud banging or kettling noises because of a buildup of limescale or poor water circulation, which is causing parts to overheat.

Est. cost
£150-300
Parts
Primary Heat Exchanger, System Filter, Central Heating Pump
Full guide for HEATING BODY NOISE
06
INSUFFICIENT WATER FLOW High Engineer

Your boiler is struggling to detect the flow of water necessary to ignite and provide you with heating or hot water.

Est. cost
£120-250
Parts
Water flow switch, Diaphragm, Venturi
Full guide for INSUFFICIENT WATER FLOW
Parts most often replaced

on the Chaffoteaux Britony II 40FF

Temperature Sensor (NTC Thermistor)Circulation PumpHeat ExchangerFilling loopExpansion vesselPressure sensor

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 Chaffoteaux 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 37-code list for the Chaffoteaux Britony II 40FF

Related guides

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