Common problems guide

The most common Halstead Ace HE problems

The faults most likely to send a Halstead Ace HE 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.
18 documented codes
6 most common
0 DIY-safe checks
6 engineer needed

The 6 most common faults

03
2 Engineer

Differential check faulty/Flame for 15 seconds, Zero check faulty DHW or CH

Full guide for 2
05
5 Engineer

Defective sensor or thermal fuse gone, Defective flow, return or flue sensor, or heat exchanger reached maximum safe working temperature

Full guide for 5
06
6 Engineer

Defective gas valve/Flame continues after 5 sec flame signal after burner demand ends

Full guide for 6

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 18-code list for the Halstead Ace HE

Related guides

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