fixmyplumbing

Simple explanations for plumbing problems

F1 low pressure fault on an Ideal Logic boiler

Why does my Ideal Logic Boiler show F1?

When the system pressure on an ideal logic drops too low the boiler displays an f1 fault. Once the pressure has been topped up to above 1bar the boiler will start working again without having to be reset. Pressing the reset button will not clear an F1 fault, you have to increase the pressure.

How do I clear an F1 fault?

Most ideal logics have integral filling loops fitted on the valves under the boiler. If you have two blue valve handles on the two right hand valves you have an integral filling loop.

Ideal logic integral filling loop.


The right hand valve is on the heating system. The left hand valve is attached to the cold mains water pipe.

To top up the pressure we need to get water from the left hand valve into the right hand valve. Before you start turn the heating off on the timer or thermostat and make sure no hot taps are running.

Step 1 : Turn the right hand blue valve toward you.

Ideal logic filling loop with right hand valve open left hand valve closed.
Ideal logic filling loop with right hand valve open left hand valve closed.

Step 2: Turn the left hand blue valve slowly toward you. When you hear the water flowing stop turning the valve. It may only need to be slightly open to fill the system up.

Ideal logic filling loop with both valves open
Ideal logic filling loop with both valves open



Step 3: Watch the needle on the pressure gauge, it should be slowly rising. When the needle gets to just above 1bar turn the valves back to where they were originally.

Ideal logic filling loop with both valves closed
Ideal logic filling loop with both valves closed

The fault code should now be cleared. The boiler will start up and the pump will run. The heating and hot water should now work when you use them.

Next steps after an F1 fault

The final step is to find out why the pressure has gone down. Looks for leaks on the boiler, the radiators and the pipe work feeding the radiators. Even slight leaks can cause the pressure to drop over time.

If the pressure drops repeatedly after topping it up it indicates a fault which needs to be addressed.

WARNING: if you leave the left hand blue valve facing fully toward you no hot water will come out of the hot tap. Be sure to put the blue valves back to their original position when you are finished.

Topping up the pressure didn’t clear the F1 fault

If there is still an F1 fault when the pressure gauge is above 1bar then there is a fault with the boiler.

The pressure sensor inside the boiler is either chocked up with dirt or is faulty.

« Boiler faults


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