Vaillant F22: Low water pressure (dry fire protection)
Usually a quick fixWhat it means
Pressure has dropped below about 0.5 bar so the boiler will not run.
Safe things to try first
- Top up via the filling loop to 1.2 bar. Press reset.
When to call an engineer
If the pressure falls again within days, there is a leak or expansion vessel fault.
Never remove the boiler cover or work on gas components yourself. It is illegal unless you are Gas Safe registered, and it will void your warranty.
Fix Vaillant F22 today
Boiler repair from £75. 92% of repairs fixed on the first visit with parts from the van.