Common problems guide

The most common Chaffoteaux Celtic 2 24 Rsc problems

The faults most likely to send a Chaffoteaux Celtic 2 24 Rsc 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.
35 documented codes
6 most common
3 DIY-safe checks
3 engineer needed

The 6 most common faults

01
2a High DIY-safe

Your boiler is making loud noises because the water pressure inside your heating system has dropped too low to operate correctly.

What to try first

Locate the external filling loop, which is a silver braided hose with one or two valves located underneath your boiler.Gradually open the valve(s) to allow mains water into the system while watching the pressure gauge on the front panel.Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, and ensure the valves are fully closed.

Est. cost
£0-90
Parts
Filling loop, Pressure relief valve, Pressure gauge
Full guide for 2a
02
6.iii High DIY-safe

Your boiler is failing to ignite because it cannot detect enough water pressure to run safely.

What to try first

Locate the external filling loop, usually two silver or black valves with a braided hose underneath the boiler.Slowly open the valves to let water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves tightly and restart the boiler.

Est. cost
£80-150
Parts
Pressure relief valve, Pressure sensor, Expansion vessel
Full guide for 6.iii
03
12 High DIY-safe

Your boiler has lost the correct water pressure needed to run efficiently and will not provide heating or hot water until this is corrected.

What to try first

Locate the external filling loop, usually a small silver braided hose with one or two valves located underneath the boiler.Gradually open the valve(s) to allow mains water into the system while watching the pressure gauge on the front of the boiler.Close the valve(s) securely once the needle reaches the green zone, typically between 1 and 1.5 bar.

Est. cost
£80-150
Parts
Pressure Relief Valve, Pressure Sensor, Expansion Vessel
Full guide for 12
04
PILOT WILL NOT LIGHT High Engineer

Your boiler is failing to ignite because internal air is preventing the gas from reaching the burner correctly.

Est. cost
£120-250
Parts
Gas valve, Ignition electrode, PCB
Full guide for PILOT WILL NOT LIGHT
05
PUMP NOT RUNNING High Engineer

Your boiler's water pump is failing to start, which means the system cannot circulate hot water to your radiators or taps.

Est. cost
£120-250
Parts
Circulating pump, Diverter valve microswitch, Fuse
Full guide for PUMP NOT RUNNING
06
2b High Engineer

Your boiler is struggling to circulate water, which is causing a loud noise because the internal pump has stopped working.

Est. cost
£150-250
Parts
Central heating pump, Pump capacitor, Printed Circuit Board (PCB)
Full guide for 2b
Parts most often replaced

on the Chaffoteaux Celtic 2 24 Rsc

Filling loopPressure relief valvePressure gaugePressure sensorExpansion vesselPressure Relief 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 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 35-code list for the Chaffoteaux Celtic 2 24 Rsc

Related guides

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