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  • Vaillant F75 is a common fault code that displays on most boilers, but why?

    Vaillant boilers are one of the best boilermakers on the market today.

    They have been producing boiler for many years now, are built with quality parts, to ensure a long working life.

    So let’s now, find out why the Vaillant F75 fault code is so common.

    The most common cause of this problem is down to water pressure.

    Should the system pressure drop below 0.5 of a bar, F75 will appear on the display.

    A simple fix is to top up the system pressure.


    Once the pressure has been increased, the fault will disappear.

    You may have to push the reset button.

    If the system pressure keeps dropping, further investigation is needed to trace the leakage so it can be repaired.

    Dirty system water is another common cause of the F75 code.

    When the boiler starts up, the pump spins, and the internal pressure is sensed by a water pressure switch.

    These switches clog up with sludge, thus, the switch cannot sense the pressure and the boiler goes to lockout.

    If this is the cause, the system will need cleaning with a chemical cleaner, flushed and inhibitor added.

    The switch may need to be replaced.

    F75 can also sometimes be down to a faulty pump, though, this is very unusual.

    Even the internal expansion vessel, can be the cause of this fault.

    The best way to avoid the F75 code is to have regular servicing on the boiler.

    When the boiler is serviced, many parts are checked, one of them being the water quality.

    Dirty water causes many problems on all boilers, not just Vaillant.

    It’s always a good idea when arranging a boiler service, to use an engineer who is Vaillant advanced trained.

    Look after your boiler and your boiler will look after you.