Valliant Ideal WLx boiler problems

[clairlee]

Hoping someone can help.
I have a valliant ideal wlx boiler, which is over 20yrs old. It is set to 'water only' but the heating is coming on also.
I have been told that the boiler is now obsolete. Can this problem be fixed and if so is it an expensive job? Or do I need a new boiler? Hoping that may be the case, as I have a warmfront grant and they will not replace unless its unfixable!
Any info/advice greatly appreciated.
Clair

 

[namsag]

Firstly it not a vaillant. It is just an ideal wlx the fault is not with the boiler but the controls it will be a faulty motorised valve or if old gravity system a faulty antigravity valve.