Ideal [F3] fault codewhat it means and how to fix it

Ideal classify this as an F code rather than an L code, which tells you something: the appliance expects it may be able to recover, and their own user guide says to restart the boiler and see. That is worth trying once, because a fan that has stalled rather than failed will sometimes pick up.

What you should not do is keep trying. Behind F3 is a hard interlock — the board compares commanded fan speed against the speed actually reported back, and it will not release the gas valve while those disagree, because the fan is the only thing moving combustion products out of the building. Ideal are also unusually specific in service literature about the air pressure switch tube on some models, a small clear pipe that can perish or fill with condensate and throw this code with a perfectly healthy fan attached. It is a five-minute check for an engineer and a frequent cause of unnecessary fan sales.

1. 1

   Restart the appliance once. Ideal specifically suggest this for F3 in their user guide, and unlike a lockout code it is a reasonable first move rather than a bad habit.

2. 2

   Stand near the boiler as it tries to start and listen. Silence, a rattle, and a grinding drone each point somewhere different, and it is the one observation an engineer cannot make retrospectively.

3. 3

   Have a look at the flue terminal from ground level, and think about whether anything has been built, fenced or planted near it recently.

   Looking is fine. Never push anything into a flue terminal.
4. 4

   When you book, ask whether the appliance is still inside its Ideal guarantee — they run long, and calling an independent engineer while covered can forfeit the balance.