Ideal boiler fan runs but the burner does not light
An Ideal boiler normally runs its fan as part of the ignition sequence, and some models also use a fan overrun after the burner stops. If the fan continues during an active demand but no flame is established, the boiler may retry and then show an ignition lockout. Record the sequence once and do not remove the casing.
The sound of a fan does not prove that gas is flowing, that ignition is taking place or that the fan itself is faulty. The display, timing and exact Ideal model are more useful than a guessed component.
Could this be normal fan operation?
At the start of a demand, the fan can run before the burner lights as the boiler prepares for ignition. At the end, an overrun can continue briefly to manage the operating sequence. Ideal technical guidance for current Logic models says the fan overrun must not be interrupted by switching off the electrical supply.
A short fan period followed by a flame symbol and normal heat is expected. A fan that runs through repeated attempts without a flame, or a sequence that ends in a fault, is different.
Record one complete sequence
From a safe distance, note what happens after the thermostat calls for heat or one hot tap opens. Does the display show a radiator or tap demand? When does the fan sound begin? Is there any ignition sound, flame symbol or code?
Stop after one naturally occurring observation. Do not repeatedly create demand to reproduce the fault. A short video of the closed front panel and sound can help an engineer if it can be made safely.
Identify the exact Ideal model and code
Photograph the full display before using restart. Ideal codes vary by range. On relevant Logic products, L2 or L 02 denotes ignition lockout, while F3 is a fan fault. A running fan with no flame should not automatically be labelled F3 unless the matching manual says so.
Some current Ideal guides also use messages such as “Ignition Lockout” and “Too Many Restarts” rather than relying only on short codes. Record every word, letter and number exactly.
Confirm there is still a heat demand
For central heating, make sure the programmer is in an active period and the room thermostat is set above the measured room temperature. For a combi, open one hot tap and watch whether the tap-demand symbol appears. Then stop testing.
If the fan runs after demand has ended, it may be completing overrun. If the fan runs while a clear demand remains but the flame never appears, that is useful evidence for professional diagnosis.
Check the gas supply only in ordinary use
Ideal’s homeowner guidance for ignition lockout on relevant products suggests checking whether another gas appliance works normally to establish whether the property appears to have a supply. This does not prove that pressure and flow at the boiler are correct.
Do not loosen connections, touch a gas valve or use a flame to check for gas. If you smell gas, avoid electrical switches and flames, open doors and windows, leave if necessary and call the National Gas Emergency Service on 0800 111 999.
Check the pressure
Read the system pressure when cool and compare it with the exact Ideal user guide. Some Logic user guidance uses roughly 1–1.5 bar as the normal range, but this is not a universal figure for every product and system.
Low pressure can stop normal operation or create a separate fault. Do not add water when the reading is already normal. If the manual permits homeowner repressurising, follow that method once and stop at the stated cold pressure.
Cold weather and the condensate pipe
Ideal’s user guidance for some ignition-lockout conditions includes checking an external condensate pipe for blockage. Freezing weather, visible ice and a safely accessible external plastic route make this more relevant.
Do not open the boiler, dismantle the condensate trap, climb or use a flame. Follow only the homeowner procedure for the exact model. If the pipe is inaccessible or the boiler still fails, arrange an engineer.
One restart only when the guide says so
If the exact Ideal user guide tells you to restart for the displayed fault and there are no gas, electrical or carbon monoxide warning signs, perform one restart and allow the sequence to finish.
Stop if the fan runs again without a flame or the lockout returns. Ideal professional guidance shows that repeated failed ignition attempts can lead to lockout and that too many restarts can produce a separate message. Repeated resetting is not a repair.
Why the fan can run without proving a fan fault
The ignition sequence coordinates controls, airflow, gas and flame detection. A fan sound only tells you that something is rotating or airflow is being attempted. It does not confirm correct speed, pressure, gas supply, ignition or flame sensing.
Ideal’s professional fault-finding information separates ignition lockout, flame loss and fan fault. Those categories require internal tests that householders should not perform.
Possible professional diagnostic areas
A Gas Safe registered engineer may need to check fault history, gas inlet pressure under demand, combustion-air and flue conditions, ignition and detection components, condensate drainage, electrical supply, fan performance and boiler controls.
The symptom alone cannot identify a gas valve, electrode, fan, sensor, wiring harness or circuit board. Do not order a part from a forum diagnosis or an unrelated model’s code.
Keep a short fault timeline
Write down the selected service, the display message and the seconds between demand, fan sound and lockout. Note whether the boiler retries by itself, whether the same sequence affects heating and hot water, and whether it follows a power cut or freezing weather.
Do not extend the test to create more evidence. One naturally occurring sequence and a photograph of the display are usually more useful than repeated restarts, because they preserve the order in which the boiler detected the problem.
Do not interrupt fan overrun unnecessarily
When the boiler has ended a normal demand without a safety warning, allow the fan to finish its overrun. Cutting power every time a fan continues briefly can interrupt intended operation.
This does not override emergency action. If you smell gas, see smoke or scorching, hear dangerous electrical sounds, find water on electrics or a carbon monoxide alarm sounds, stop normal testing and follow the relevant emergency advice.
What not to do
- Do not remove the boiler casing.
- Do not repeatedly restart failed ignition attempts.
- Do not adjust the gas valve or fan settings.
- Do not clean or bend electrodes.
- Do not open the condensate trap or flue.
- Do not assume a running fan means the fan is healthy or faulty.
When to arrange a repair
Book professional diagnosis if a clear demand is present but the flame never establishes, an ignition-lockout message returns after one permitted restart, the fan runs through repeated attempts, or heating and hot water remain unavailable.
Turn the boiler off using its normal control when it is suspected to be unsafe and this can be done safely. HSE says an unsafe gas appliance must not be used until checked by a Gas Safe registered engineer.
What to tell the engineer
- the complete Ideal model name;
- the exact message or code;
- whether the fan runs before, during or after demand;
- whether any flame symbol appears;
- whether heating, hot water or both are affected;
- the cool-system pressure; and
- recent power, gas-supply, weather or control changes.
Gas and carbon monoxide safety
If a carbon monoxide alarm sounds or anyone has headache, dizziness, nausea, weakness, confusion, chest pain or breathing difficulty, go outside and seek medical help. Call 999 for severe symptoms.
Do not return to testing the boiler until advised. Carbon monoxide cannot be seen or smelled, and an alarm is not a substitute for competent appliance checks.
Frequently asked questions
Is it normal for an Ideal boiler fan to run before ignition?
Yes, brief fan operation can be part of the normal ignition sequence. The concern is repeated fan operation without a flame or a resulting lockout.
Does L2 mean the fan is broken?
On relevant Ideal Logic models, L2 means ignition lockout. Fan fault is listed separately. Always use the manual for the exact model.
Should I switch the power off while the fan runs?
Do not interrupt a normal fan overrun. If there is a safety warning, follow emergency guidance rather than treating it as ordinary overrun.
Can a blocked condensate pipe prevent ignition?
It is included in Ideal guidance for some ignition-lockout cases. Check only an accessible external route and never open the boiler.
Can I keep pressing restart?
No. Use one restart only when the exact guide instructs it. A returning lockout needs professional diagnosis.