Boiler bar symbol flashing, filling pressure outside permitted range

[aaronmaoeric]

When turn on Vaillant ecoTEC plus, bar symbol flashing from time to time, indicate filling pressure outside permitted range(around 3.1bar), when flashing the burner turn on as well. I've tried to drained radiator to lower pressure but doesn't work. Advice are highly appreciated.

 

[motorbiking]

When you drain the radiator does the pressure drop and then slowly rise again? You may have nocked the fill loop valve and its slightly open.

 

[aaronmaoeric]

Thanks for your comment, the pressure drop from 3.2 bar to 2.8 bar when drain the radiator, then it appears error of F75(water shortage), I need to open fill loop valve to turn on boiler. Then just keep the same phenomenon.

 

[ianmcd]

shut down all demands for heat from the boiler, then get the pressure to 1.5Bar then turn the heating on

 

[oldbutnotdead]

Is there a bleed valve at the top of that boiler- possible you've got an air bubble stuck in there

 

[Deleted member 267285]

then it appears error of F75(water shortage), I need to open fill loop valve to turn on boiler. Then just keep the same phenomenon.

You need a gas safe registered engineer to change a part inside your boiler, keeping on topping up the pressure will do it no good. Whilst they’re doing that get the, to charge the expansion vessel and check to ensure the prv is seating or ask them to bring a new one anyway.