Common problems guide

The most common Alpha CB 240 / 280 problems

The faults most likely to send a Alpha CB 240 / 280 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.
9 documented codes
6 most common
1 DIY-safe checks
5 engineer needed

The 6 most common faults

01
Red reset button illuminated High DIY-safe

Your boiler has stopped working because it failed to ignite, but you can attempt to restart it by pressing the red reset button.

What to try first

Check that your gas supply is turned on and other gas appliances like your hob are working.Ensure your gas prepayment meter has credit if applicable.Locate the red reset button on the control panel, press it once firmly, and wait for the boiler to attempt an ignition sequence.

Est. cost
£120-250
Parts
Ignition electrode, Gas valve, Printed Circuit Board (PCB)
Full guide for Red reset button illuminated
02
neon illuminated High Engineer

Your boiler has developed an internal electrical fault, meaning the control board is likely failing and unable to safely operate the system.

Est. cost
£200-350
Parts
Neon PCB, Main PCB
Full guide for neon illuminated
03
Fan runs at max. speed High Engineer

Your boiler's fan is running continuously at full speed, which indicates the system has detected a safety concern and is trying to clear the air inside the unit.

Est. cost
£150-300
Parts
Air pressure switch, Flue sampling tube, Printed circuit board (PCB)
Full guide for Fan runs at max. speed
04
Spark at ignition electrodes High Engineer

Your boiler is struggling to light its internal flame, which means it cannot produce the heat or hot water you need.

Est. cost
£120-250
Parts
Ignition electrode, Ignition lead, PCB (Printed Circuit Board)
Full guide for Spark at ignition electrodes
05
Pump circulating water / No High Engineer

Your boiler is struggling to push water around your radiators and taps, likely because there is trapped air in the system or the internal water pump has become faulty.

Est. cost
£250-450
Parts
Central heating pump, Automatic air vent
Full guide for Pump circulating water / No
06
Pump runs Medium Engineer

Your boiler's water pump is running constantly, which suggests the unit is stuck in a cycle trying to clear air or respond to a faulty thermostat signal.

Est. cost
£120-250
Parts
PCB, Flow switch, Pump relay
Full guide for Pump runs
Parts most often replaced

on the Alpha CB 240 / 280

Ignition electrodeGas valvePrinted Circuit Board (PCB)Neon PCBMain PCBAir pressure switch

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 Alpha 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 9-code list for the Alpha CB 240 / 280

Related guides

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