F.22
Vaillant fault code
Vaillant F.22: low water pressure in the system
You can usually fix this
The water pressure in your heating system has dropped below what the boiler needs, so it has stopped to protect itself. This is the most common Vaillant code and usually something you can fix in a few minutes.
Recommended pressure when cold for Vaillant boilers: 1.0 to 2.0 bar.
What you can safely do
- Let the boiler cool down, then read the pressure gauge on the front.
- Top up using the filling loop (usually under the boiler) until the gauge reads between 1.0 and 2.0 bar with the system cold. Your user manual shows where the filling loop is.
- Close the filling loop fully, then clear the fault using the reset key as your manual describes.
Call a Gas Safe engineer if
- The pressure drops again within a few days. Water is escaping somewhere.
- You can see water dripping from the boiler or pipework.
- You can't find the filling loop or aren't sure how to use it.
Find a Gas Safe engineer near you
Opens the official Gas Safe Register search.
Applies to: ecoTEC plus. Codes can differ between models, so check your manual.