Ferroli A14 Fault Code: Causes, Fixes & Repair Costs
What does the Ferroli A14 fault code mean?
The A14 code appears on Ferroli boilers when the flue extraction duct safety device has been triggered as a result of the F07 fault (high flue gas temperature) occurring three times within a 24-hour period. Rather than a single isolated event, A14 is a cumulative lockout — the boiler is telling you the same dangerous flue temperature condition has repeated itself enough times that it refuses to restart without manual intervention. Ferroli uses 'A' prefix codes to indicate hard lockouts that will not clear on their own; the boiler stays off until someone physically resets it and, crucially, until the underlying problem is resolved. The root fault (F07) points to flue gases not being expelled efficiently, which can create a combustion safety risk — so this lockout should be taken seriously and not bypassed through repeated resets.
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
- Blocked or obstructed flue terminal Common
A partially or fully blocked flue outlet is the most frequent trigger for repeated F07 events. Debris such as leaves, bird nesting material, or even a build-up of ice during cold weather can restrict the flow of exhaust gases, causing temperatures to spike. Check the external terminal from ground level for any obvious obstruction — this is the one visual check a homeowner can safely carry out.
- Faulty or failing flue fan Common
The fan is responsible for drawing combustion gases out through the flue. If it is struggling — due to worn bearings, debris caught in the blades, a faulty tachometer signal, or a loose electrical connection — it cannot maintain adequate extraction. This causes flue gas temperatures to rise repeatedly, triggering F07 and ultimately A14. A Gas Safe engineer will test the fan speed, tachometer output, and wiring.
- Defective flue stat or temperature sensor Sometimes
The flue stat is a small safety sensor mounted close to the flue pipe that monitors exhaust gas temperature. If this component has drifted out of calibration, developed a fault, or its wiring has corroded, it may be falsely reporting high temperatures even when the flue is clear and the fan is working correctly. Sensor replacement is a relatively straightforward and cost-effective repair for an engineer.
- Flue duct corrosion or loose joints Sometimes
On older installations, the flue duct itself can deteriorate — joints may loosen over years of thermal cycling, or internal corrosion can partially restrict airflow. A boiler making unusual puffing or air sounds when firing can be a sign of flue duct issues. An engineer will inspect the full flue run, not just the terminal, to look for leakage or restriction points.
- Heat exchanger scaling or blockage Rare
A scaled or partially blocked heat exchanger forces the boiler to work harder to transfer heat, which can lead to elevated flue gas temperatures downstream. This is more likely on older boilers or those on hard water supplies without adequate inhibitor treatment. Heat exchanger issues are among the more costly repairs and are a reason to weigh up replacement on ageing units.
How to fix it
- Check the external flue terminal for visible blockages DIY safe
From ground level or a safe vantage point, look at the flue outlet on the outside wall or roof. Check for obvious obstructions such as bird nests, debris, or ice. Do not climb ladders to access the terminal yourself — if it is out of safe reach, leave this for the engineer.
- Check whether the condensate pipe is frozen DIY safe
In cold weather, a frozen condensate pipe can indirectly contribute to flue-related faults. The condensate pipe is typically a white plastic pipe running from the boiler to an outside drain. If it feels solid or has visible ice, you can carefully thaw it using warm (not boiling) water poured along its length, or wrap it with a warm damp cloth. Once thawed, attempt a single reset.
- Attempt a single manual reset DIY safe
Most Ferroli boilers have a dedicated reset button on the control panel, often labelled 'R' or marked with a reset symbol. Press and hold it for one to two seconds. If the boiler fires up and runs normally, monitor it closely. If A14 returns within a short period, do not keep resetting — the boiler is detecting a genuine recurring problem and repeated resets risk damaging the heat exchanger or fan.
- Do not reset the boiler more than once or twice DIY safe
Because A14 is already the result of F07 occurring three times, the underlying fault is persistent. Forcing the boiler to fire repeatedly without resolving the root cause can cause accelerated wear or heat damage to expensive components. If the fault returns after one reset attempt, stop and arrange for an engineer.
- Have a Gas Safe engineer inspect and test the flue system Gas Safe engineer
An engineer will carry out a full flue inspection from the boiler casing to the external terminal, checking for obstructions, corroded sections, and loose joints. They will also test flue gas composition to confirm safe combustion.
- Engineer to test the fan and tachometer signal Gas Safe engineer
The engineer will check the fan is spinning at the correct speed, that the tachometer feedback signal to the PCB is within specification, and that all electrical connections to the fan are secure and undamaged. A failing fan will be replaced.
- Engineer to inspect and test the flue stat and temperature sensor Gas Safe engineer
The flue stat and any associated temperature sensors will be tested for accuracy and continuity. If a sensor is reading falsely high or has failed open-circuit, it will be replaced. The engineer will also check the wiring loom between the sensor and PCB for corrosion or damage.
- Engineer to assess the heat exchanger Gas Safe engineer
If the above checks do not identify the fault, the engineer will inspect the heat exchanger for scale build-up, partial blockage, or physical damage. On older boilers, a scaled heat exchanger may warrant a broader conversation about the cost-effectiveness of repair versus replacement.
- Call a Gas Safe registered engineer if in any doubt Gas Safe engineer
A14 is a combustion safety lockout. If you are unsure of the cause, if the boiler has locked out more than once recently, or if any reset attempt fails, call a Gas Safe registered engineer. Do not attempt to remove the boiler casing, inspect internal gas components, or interfere with the fan or PCB yourself.
Parts you may need
- Flue fan / exhaust fan assembly · from £85
- Flue stat / flue temperature sensor · from £25
- Fan tachometer / speed sensor · from £30
- PCB (main control board) · from £120
- Flue duct section / terminal kit · from £45
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 £100–£300, depending on the underlying cause.
Frequently asked questions
Can I just keep resetting my Ferroli boiler to clear the A14 code?
No — and it is worth understanding why. A14 only appears after the underlying F07 fault has already triggered three times in 24 hours, so the problem is clearly recurring. Resetting the boiler forces it to fire despite an unresolved flue or fan issue, which risks heat damage to the heat exchanger and puts additional stress on the fan. One careful reset attempt is reasonable; if A14 comes back, stop resetting and call a Gas Safe engineer.
What is the difference between Ferroli F07 and A14?
F07 is a blocking fault meaning the boiler has detected high flue gas temperature on a single occasion — it may clear automatically once the condition passes. A14 is a hard lockout that activates when F07 has occurred three times within 24 hours. Once A14 is displayed, the boiler will not restart without a manual reset, and the underlying cause (blocked flue, fan fault, faulty sensor) must be identified and fixed to prevent it recurring.
How much does it cost to fix a Ferroli A14 fault in the UK?
Most people with an A14 fault pay between £100 and £300 all in. A straightforward engineer visit for diagnosis, flue clean, and reset typically costs £80 to £150. Replacing a flue stat or temperature sensor adds £80 to £120 including labour, while a fan replacement typically runs £180 to £250. In less common cases where the PCB needs replacing, expect £200 to £300. Heat exchanger replacement is significantly more expensive and, on an older Ferroli, often tips the balance towards fitting a new boiler.
My Ferroli boiler is over 10 years old and keeps showing A14 — should I repair or replace it?
If your boiler is more than 10 years old and repair quotes are reaching £400 or more, it is worth comparing that against the cost of a new boiler installation (typically £1,800 to £2,800 for a mid-range combi). Older Ferroli models can also have parts availability issues that extend repair times. A Gas Safe engineer can give you an honest assessment, but as a rule of thumb, if repair costs exceed 30–40% of a replacement boiler's price, replacement usually makes better financial sense.