• You are here:
    Boilers Vaillant Eco-Tec Fault Code F 75

  • One of the most common fault codes with the Vaillant Eco-Tec is F 75. 

    This normally due to low water pressure, most of the time just by increasing the pressure to 1.2 bar and hitting the reset button the boiler will fire up. 

    Should the fault code show up again then further investigation needs to be carried out?

    Low water pressure is due to the system losing pressure somewhere, the boiler senses this and shuts down to protect itself. This problem will need to be rectified should it become a regular thing.

    So what are the reasons for low water pressure?

    It means the system is losing pressure somewhere so

    The first check is to make sure there are no leaks on the system, 

    check around the radiator valves, look for marks on the ceiling, look for any signs of staining.

    The Vaillant Eco-Tec has a built in expansion vessel,

    this takes up the water expansion as the water heats up, 

    should the expansion vessel fail then the fault code F 75 can show up.

    Lack of service is the most common reason for the expansion vessel to fail. 

    When the boiler is serviced the expansion vessel should always be checked and reset if needed, 

    for some reason this seems to get missed out of the service. 

    The vessel is charged with air to 0.75bar when it leaves the factory.

    Over time the vessel will loose its charge,

    when this happens the vessel will start to fill with water.

    If the vessel has water in when the boiler is working,

    you will notice the pressure increasing to a point where once it reaches 3 plus bar,

    it will start to discharge the pressure through the safety valve. If this happens then the Fault code F 75 will display

    If you notice your boiler pressure rising into the high zone,

    and it has not done this before then you need to call in your local gas safe boiler engineer to check over your boiler and ask them to check the expansion vessel

    Sometimes fault code F 22 will appear instead of the F 75,

    Both of these fault codes have similar answers when you check the Vaillant Eco-Tec book. 

    If either of these codes appear and after reseting the boiler you find the boiler does not fire up you need to call in your engineer.

    If the boiler fail to work then the pump needs to be checked to make sure it is running, 

    next is the water pressure switch. 

    These switches can get clogged up with sludge and do not detect the water pressure rise when the pump runs. 

    If this is the case then it is advisable to have your system cleaned out and an inhibitor added once the boiler has been repaired.

    The Vaillant Eco-Tec boiler is a very high Tec peace of kit and needs to be treated as such.

    If you notice any strange noise or anything out of the ordinary with your boiler, 

    then don’t leave it hoping it will go away, call someone in to check it over.

    This goes for any make of boiler.

    If you don’t do anything about it you could end up with a big invoice for the repair,

    when it eventually stops working, you may even end up having to replace it for a new one. 

    All of these high efficiency boilers of today whatever make, 

    need to be serviced and looked after.

    If you just ignore your boiler it will breakdown, and it always happens when you need it most.