Vaillant F75 & F22 error codes

Vaillant Boiler codes F75 & F22 mostly just mean system pressure is low and needs re pressurizing.

To do this you just need to locate the filling valves/loop.

Turn them on slowly until the pressure gauge reeds 1.2 to 1.5 and turn them back off.

Your boiler should automatically start to cycle if not press the reset button and turn on a demand ie hot tap or heating control.