F1 fault on an Ideal boiler

An F1 fault is caused by low pressure in the central heating system with Ideal logic boilers.

Fault code on ideal logic
Fault code on ideal logic

When the pressure is too low the boiler won’t work at all so you’ll have no heating or hot water.

Fault code on ideal logic
Fault code on ideal logic

Using the reset button or switch has no effect on F1 faults. The fault can only be cleared by increasing the pressure.

Pressure gauge
Pressure gauge

Check the pressure by using the pressure gauge. On older models it is hidden under the boiler on the left. On more modern versions it is on the front of the boiler.

Ideal logic filling loop
Ideal logic filling loop

The pressure is increased using the filling loop. On most Ideal logics this is built in under the boiler on the right hand side. There may be an external filling loop, this guide can help you identify it.

Before starting make a note of the positions of the valves. When you are finished return them to the original position.

Turn the left hand blue valve toward you. Next slowly turn the right hand blue valve toward you until you can hear water running. Carefully watch the needle on the pressure gauge go up. When it gets between 1 and 1.5 turn the right hand back to where it was and do the same with the left hand valve.

The F1 fault should be clear now. If the pressure is between 1 and 1.5 and the boiler still has an F1 fault the pressure sensor may be faulty which requires a gas safe engineer to repair it.

If you get an F1 fault displayed on your boiler and you have to top up the pressure regularly you may have a leak or fault on your heating system. That should be investigated by a plumber or heating engineer.

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