how do I rectify the fault as detailed below?
Vaillant 630 error f 85?
Vaillant igniting issue ( domestic ) not CH?
Vaillant condensing boiler ecoTEC plus?
No hot water, intermittent when air temp drops?
Boiler over pressure on the hot-water side?
how to fix water pressure its down at bottom of grey part?
Hot water comes and goes!?
Vaillant VCW-Sine18 T3WFH Lights but then goes off after 5 Min?