Common problems guide

The most common Halstead iHeat 24c problems

The faults most likely to send a Halstead iHeat 24c 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.
4 documented codes
4 most common
2 DIY-safe checks
2 engineer needed

The 4 most common faults

01
Red LED On permanently High DIY-safe

Your boiler has switched itself off because it has become too hot to operate safely.

What to try first

Check that all radiator valves are fully open to allow water to flow.Ensure there is enough pressure in the system by checking the gauge is between 1.0 and 1.5 bar.Wait 30 minutes for the unit to cool down and then press the reset button.

Est. cost
£100-£350
Parts
Circulation pump, Overheat thermostat, Main Heat Exchanger
Full guide for Red LED On permanently
02
Red LED On every 0.5 second High Engineer

Your boiler has detected a serious internal problem or a safety issue and has locked itself down to prevent damage.

Est. cost
£120-350
Parts
Main PCB, Ignition Electrode, Overheat Thermostat
Full guide for Red LED On every 0.5 second
03
Green LED On every 0.5 second Low DIY-safe

Your boiler has paused temporarily and is waiting for conditions to return to normal before it attempts to start again.

What to try first

Check if the water pressure is between 1.0 and 1.5 barEnsure your gas supply is active (e.g., check other gas appliances)Wait 15 minutes to see if the boiler resets itself automatically

Est. cost
£0-120
Parts
NTC Temperature Sensor, Water Pressure Switch
Full guide for Green LED On every 0.5 second
04
Yellow LED On permanently Medium Engineer

Your boiler has detected a problem with the hot water system, meaning you likely have no hot water even if the heating is still working.

Est. cost
£90-210
Parts
DHW Temperature Sensor (NTC), Flow Switch, Diverter Valve
Full guide for Yellow LED On permanently
Parts most often replaced

on the Halstead iHeat 24c

Circulation pumpOverheat thermostatMain Heat ExchangerMain PCBIgnition ElectrodeOverheat Thermostat

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 Halstead 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 4-code list for the Halstead iHeat 24c

Related guides

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