Andrews A19 Fault Code: Causes, Fixes & Repair Costs
What does the Andrews A19 fault code mean?
The A19 code appears on certain Andrews water heater and boiler displays, but its precise definition varies depending on which model and control system you have. Andrews commercial units use Honeywell-integrated burner controls, and on these systems a fault in the '19' range is most commonly associated with a main flame failure or ignition fault — specifically, the burner either failing to establish a flame during the ignition sequence or losing the flame signal unexpectedly. However, because Andrews produces several distinct ranges (ClassicFlo, HiFlo, CombiFlo and others), the A19 label is not universally documented in public fault-code lists. If the description below does not closely match what your appliance is doing, check your model's installation and service manual or contact Andrews Water Heaters directly before proceeding.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Flame failure during ignition sequence Common
The burner attempts to light but the control board receives no flame signal, or loses it within the first few seconds. This is the most typical presentation of a code-19 style fault on Honeywell-controlled commercial burners. Possible root causes include a weak spark, contaminated electrodes, or insufficient gas reaching the burner.
- Gas supply interruption or low gas pressure Common
If the incoming gas pressure drops below the appliance's minimum requirement — due to a closed isolation valve, meter issue, or network supply problem — the burner cannot sustain a flame and the control locks out. On commercial units serving large premises this is worth ruling out early.
- Faulty or dirty UV flame-detection scanner Sometimes
Andrews commercial units often use an ultraviolet (UV) scanner rather than an ionisation probe to detect the flame. If the scanner lens is sooty, the scanner is misaligned, or the component has failed, the control board never receives a satisfactory flame-present signal even if the burner does light.
- Ignition electrode wear or misalignment Sometimes
Over time the ignition electrode gap can widen, the tip can erode, or the electrode lead can develop a hairline crack. Any of these reduce spark energy to the point where reliable ignition cannot occur.
- Gas valve fault Rare
A gas valve that is slow to open, stuck, or failing internally can starve the burner of fuel during the ignition window, causing a lockout. This is a less common cause but is more likely on older appliances or those that have seen infrequent servicing.
- PCB or Honeywell control module fault Rare
If the integrated control module itself has developed a fault — damaged relay, corrupted programming, or component failure — it may falsely report a flame-failure condition even when the burner and gas supply are functioning correctly.
How to fix it
- Check that the gas supply to the appliance is fully open DIY safe
Locate the isolation valve on the gas supply pipe to the Andrews unit and confirm the handle is in line with the pipe (open). If other gas appliances in the building are also not working, contact your gas supplier or Cadent/SGN before doing anything else.
- Attempt a single reset of the appliance DIY safe
Most Andrews commercial units have a dedicated reset button or sequence — consult the user section of your manual for the exact method. Press reset once. If the appliance locks out again within a few minutes, do not keep resetting; repeated reset attempts on a commercial gas appliance can be unsafe and may indicate a genuine gas or combustion fault.
- Check for any visible error or sub-code on the display DIY safe
Some Andrews models display an additional numeric or alphanumeric sub-code alongside A19. Note down the full display reading exactly as shown and have it ready when you call an engineer — it can help them diagnose the fault before they arrive.
- Do not attempt to open the appliance casing or access internal components Gas Safe engineer
Andrews commercial water heaters are gas appliances. Opening the casing, adjusting the gas valve, touching the ignition electrodes, or interfering with the burner assembly must only be done by a Gas Safe registered engineer with relevant commercial appliance experience.
- Have a Gas Safe registered engineer carry out a full inspection Gas Safe engineer
Given the commercial nature of Andrews appliances, contact a Gas Safe engineer who has experience with commercial water heaters or catering equipment. They will check gas inlet pressure, inspect and clean or replace the UV scanner and ignition electrode, test the gas valve operation, and interrogate the Honeywell control module for stored fault history. Ask them to bring your model number so they can obtain the correct parts if needed.
Parts you may need
- UV flame-detection scanner (Honeywell compatible) · from £85
- Ignition electrode assembly · from £45
- Honeywell integrated burner control module · from £280
- Gas valve (commercial Andrews-compatible) · from £220
- Ignition lead and connector set · from £30
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £180–£500, depending on the underlying cause.
Frequently asked questions
Is the Andrews A19 fault code the same on all Andrews models?
No. Andrews produces several different ranges of commercial water heaters and uses more than one generation of Honeywell control system across them. The A19 display is not universally defined in publicly available documentation, and its meaning can differ between the ClassicFlo, HiFlo, and CombiFlo ranges. Always cross-reference the code against your specific model's installation and service manual. If you do not have the manual, Andrews Water Heaters (andrewswaterheaters.co.uk) can usually supply a copy or confirm the code meaning over the phone.
Can I fix an Andrews A19 fault myself?
In most cases, no. Andrews appliances are commercial gas water heaters, and almost all of the components involved in a flame-failure lockout — the gas valve, burner, UV scanner, ignition electrode, and control module — must only be worked on by a Gas Safe registered engineer. The only safe DIY checks are confirming the gas isolation valve is open and attempting one reset. If the lockout persists, call an engineer.
How much will it cost to repair an Andrews A19 fault?
Most repairs for this type of fault fall in the range of £180–£500 including parts and labour. A UV scanner or ignition electrode replacement will typically sit at the lower end of that range, while a Honeywell control module or gas valve replacement will push towards the higher end. If a heat exchanger or major internal component proves to be the underlying cause, costs can exceed £600 — at which point your engineer may advise whether a full appliance replacement makes more economic sense.
Why does my Andrews boiler keep locking out with A19 even after I reset it?
Repeated lockouts after resetting almost always mean the underlying fault has not been resolved. Common reasons include a UV scanner that needs cleaning or replacing, a gas supply pressure issue that is intermittent, or an ignition electrode that is too worn to produce a reliable spark. Each lockout-and-reset cycle puts additional stress on the control module. Stop resetting and call a Gas Safe engineer — continuing to reset a commercial appliance that keeps locking out is not safe practice.