Andrews A14 Fault Code: Causes, Fixes & Repair Costs
What does the Andrews A14 fault code mean?
On Andrews MAXXflo multi-burner commercial water heaters, fault codes are displayed as a letter paired with a number. The letter indicates the fault category, while the number identifies which burner module is affected. 'A' denotes a lockout fault — the most serious category, meaning the appliance has shut itself down as a safety measure and requires manual intervention before it will restart. '14' identifies burner module 14 as the module that has gone into lockout. The unit will cease firing on that module until the underlying problem is resolved and a reset is carried out. A lockout on any module is typically triggered by repeated flame failures within a single burn cycle, a control communication error between the two internal processors, temperature sensor faults, or too many consecutive user resets. Note: if your Andrews appliance is not a MAXXflo multi-burner unit, 'A14' may carry a different meaning specific to that model — always cross-reference with your own appliance's service manual or contact Andrews Water Heaters directly.
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
- Repeated flame failure on module 14 Common
The most frequent trigger for an 'A' lockout. If the burner module attempts to ignite and fails to establish or hold a stable flame three times within a single burn cycle, the control system locks out that module as a precaution. This can stem from a weak spark, poor gas delivery to that module, or a contaminated flame sensor failing to confirm ignition.
- Dirty or degraded ignition electrode or HT lead Common
Over time, ignition electrodes accumulate carbon deposits or crack, and high-tension leads deteriorate. Either condition weakens the spark, making reliable ignition on module 14 difficult. A wrongly gapped electrode — even if otherwise clean — produces the same result.
- Flame sensor or ionisation probe contamination Common
The flame sensor monitors whether a flame is actually present after ignition. If it is coated in residue or has drifted out of position, it may fail to detect a genuine flame, causing the controller to assume ignition has failed and triggering lockout.
- Frozen or blocked condensate pipe Sometimes
In cold weather, the condensate drain pipe — particularly any external section — can freeze solid. When condensate cannot escape, the appliance shuts down to prevent internal damage. This is more likely on units installed in unheated plant rooms or with long external pipe runs.
- Gas valve fault on module 14 Sometimes
If the gas valve serving that module is not opening correctly or is delivering gas at the wrong pressure, the burner will either fail to light or produce an unstable flame. A faulty valve can also cause the unit to lockout due to a perceived safety risk.
- Fan fault or incorrect fan speed Sometimes
Andrews MAXXflo units monitor fan operation closely. If the fan on or associated with module 14 runs at the wrong speed, fails to reach pre-purge speed, or stalls, the control system will lockout that module rather than allow combustion under unsafe flue conditions.
- Flow or return sensor open circuit or short circuit Sometimes
Each burner module monitors water temperature via flow and return sensors. An open circuit, short circuit, or wiring fault on either sensor will cause the controller to log a lockout fault on that module, as it cannot confirm safe operating temperatures.
- Control communication error Rare
The MAXXflo controller uses two processors that communicate with each other. If that communication breaks down — due to a PCB fault, wiring issue, or firmware error — the affected module will be locked out as a safety measure.
- Excessive user resets without resolving the fault Rare
The control system counts the number of resets attempted. If a user repeatedly resets the unit without addressing the root cause, the controller will enforce a harder lockout to prevent damage to internal components such as the electrodes and PCB.
How to fix it
- Check the gas supply to the building is on and other gas appliances are working DIY safe
Confirm that the gas meter isolation valve is open and that other appliances — for example a gas hob — are functioning normally. If there is no gas supply to the building at all, contact your gas supplier rather than attempting a reset.
- Check system pressure if a pressure gauge is fitted and top up via the filling loop if below 1 bar DIY safe
Low water pressure can contribute to lockout conditions. If the gauge reads below 1 bar, slowly open the filling loop valves to bring the pressure up to around 1.5 bar, then close the valves fully. If you are unsure how to do this on a commercial Andrews unit, wait for the engineer.
- Inspect the condensate pipe for freezing in cold weather DIY safe
If temperatures are at or near freezing, check any external section of the condensate drain pipe for ice blockage. You can thaw a frozen pipe by pouring warm (not boiling) water over it, working from the outlet end inward. Once thawed, attempt a single reset.
- Attempt a single reset of the locked-out module DIY safe
Locate the reset function on the MAXXflo control panel. The manual states that the burner module shown in the display at the time of the fault is the one that is reset. Press reset once and observe whether the module restarts and holds a stable flame. Do not reset more than two or three times without the fault being properly diagnosed — repeated resets can damage the electrode and PCB.
- If the lockout returns immediately or persists, do not continue resetting — call a Gas Safe registered engineer Gas Safe engineer
A recurring lockout on module 14 indicates an underlying fault that requires professional diagnosis. An engineer will inspect the spark electrode gap and condition, the HT lead, the ionisation probe, gas valve operation and inlet pressure, fan speed and flue integrity, and flow and return sensor wiring continuity. All service work on Andrews MAXXflo appliances must be carried out by competent, qualified personnel.
- Gas Safe engineer: inspect and test the ignition electrode and HT lead on module 14 Gas Safe engineer
Check the electrode for cracking, carbon deposits, and correct gap. Inspect the HT lead for insulation breakdown. Replace any degraded components with manufacturer-approved parts.
- Gas Safe engineer: test the flame sensor and ionisation probe Gas Safe engineer
Clean or replace the ionisation probe if contaminated. Verify the probe is correctly positioned in the flame envelope. Measure the ionisation current to confirm it is within specification.
- Gas Safe engineer: verify gas valve operation and inlet pressure on module 14 Gas Safe engineer
Check gas inlet pressure at the test point against the manufacturer's specification. Test the gas valve electrically and mechanically. Replace the valve if it is not operating correctly.
- Gas Safe engineer: check fan operation and flue integrity Gas Safe engineer
Verify that the fan associated with module 14 reaches the correct pre-purge speed and maintains stable operation during the burn cycle. Inspect the flue for blockage or restriction. A flue flow test may be required.
- Gas Safe engineer: test flow and return sensors and all associated wiring Gas Safe engineer
Use a multimeter to check sensor resistance values against the manufacturer's temperature-resistance curve. Inspect wiring looms for chafing, loose terminals, or corrosion. Replace any faulty sensor or repair damaged wiring.
- Gas Safe engineer: inspect PCB and inter-processor communication if all other checks pass Gas Safe engineer
If no mechanical or combustion fault is found, the lockout may stem from a control board fault or communication error between the two onboard processors. The PCB should be tested and replaced if confirmed faulty.
Parts you may need
- Ignition electrode (module-specific) · from £35
- High-tension (HT) ignition lead · from £25
- Ionisation / flame sensor probe · from £40
- Gas valve (module-specific) · from £220
- Flow temperature sensor · from £30
- Return temperature sensor · from £30
- Burner module fan · from £150
- Control PCB · from £320
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 £150–£450, depending on the underlying cause.
Frequently asked questions
Can I keep resetting the Andrews A14 fault to get the unit running?
You can attempt one reset after checking for obvious causes such as a frozen condensate pipe or gas supply interruption. However, resetting repeatedly without fixing the underlying fault is counterproductive — the control system on MAXXflo units actually counts the number of resets, and too many consecutive attempts will trigger a harder lockout. More importantly, each unnecessary restart cycles the ignition components under fault conditions, accelerating wear on the electrode and PCB. If the lockout returns after a single reset, call a Gas Safe engineer.
Does the A14 code mean the whole Andrews MAXXflo unit has shut down, or just one burner?
Just the affected module — in this case burner module 14. The MAXXflo is a multi-burner system, and the control panel displays the letter 'A' and the module number alternately so you can identify exactly which module is in lockout. Other modules may continue to fire and contribute to the heating load while module 14 is isolated. However, this reduces total output capacity, so the unit may struggle to meet demand in colder conditions or at peak usage times. The faulty module should still be repaired promptly.
What is the difference between an 'A' fault and an 'E' fault on an Andrews MAXXflo?
Andrews MAXXflo units use two fault categories: 'A' codes are lockout faults — the module has shut down completely and requires a manual reset along with a fix before it will restart. 'E' codes are blocking faults — the module is prevented from operating, but the condition may self-clear once the cause is resolved, without needing a full reset. In both cases, the number after the letter tells you which burner module is affected. Lockout faults ('A') are generally more serious and more likely to need engineer attention.
Could a PCB replacement be needed, and how much does that cost?
A PCB fault is one of the less common causes of an A14 lockout — most cases turn out to be ignition electrodes, flame sensors, or gas pressure issues, which are far cheaper to fix. However, if an engineer works through all the mechanical and combustion checks and finds nothing wrong, the control board becomes the prime suspect. On a commercial Andrews MAXXflo unit, a replacement PCB typically costs £250–£400 for the part alone, with labour on top. Because of the complexity of multi-burner controllers, this work should only be carried out by an engineer experienced with Andrews commercial water heaters.