Ideal [L A] fault codewhat it means and how to fix it

L A is the overheat lockout on Ideal's LED-display boilers, the window flashing L and then A, and it comes from a separate overheat thermostat rather than from the flow thermistor that produces L1 on a Logic.

Ideal's user guide gives the householder two things: hold the reset button for two seconds, after which the boiler should relight, and if the fault recurs "this indicates an overheat condition — the boiler should be turned off and your installer contacted"; and check whether every radiator has a thermostatic valve, because a system where all of them can close leaves the boiler with nowhere to send its heat. The installer chart begins with whether the system is filled, vented and its isolation valves open, then whether the overheat can be reset with the system cold, then whether the pump gives a flow-to-return differential over 25°C — a pump check — and only then, if the flow temperature passes 90°C before the trip, the control thermistor, or below 90°C, the overheat thermostat itself.

With the later V9 control board, an L A that has been reset shows three horizontal lines and will not try to fire until the heat exchanger is under 50°C, which is deliberate and not a further fault.

1. 1

   Let the boiler cool, then hold the reset button for two seconds. Ideal say it should then relight. On a V9-board Isar the display may show three horizontal lines while it waits to drop below 50°C — leave it.

2. 2

   Walk round the radiators. If every one has a thermostatic valve and none is a plain manual valve or a bypass, tell the installer: Ideal name that arrangement as a cause.

3. 3

   If L A comes back, switch the boiler off and contact your installer. Ideal's words for a recurring L A are that it indicates an overheat condition, and repeated resets of an overheat are how heat exchangers are damaged.