Vaillant ecoTEC F.22 fault code: low water pressure explained

What Does Error F.22 Mean?

Vaillant assigns F.22 to low water pressure in the sealed heating circuit, and the boiler stops firing to protect itself from running dry. Vaillant names the normal range as 1 to 1.5 bar, and lists a faulty pressure sensor, loose sensor or pump wiring, and a failed internal expansion vessel alongside a genuine water shortage. Applies to: Vaillant ecoTEC plus and ecoTEC sustain boilers that list F.22 This meaning follows the Vaillant United Kingdom fault-code list for ecoTEC boilers that display F.22. Other Vaillant ranges and the same code on another appliance can be mapped differently, so confirm the model from the data badge before you top up or reset. Owner-safe checks: Read the pressure gauge with the system cold, and top up to about 1.5 bar with the filling loop only if it is below 1 bar, then close both valves fully. | Record how many times the pressure has needed topping up in the last month and whether it drops fastest hot or cold. Qualified technician: A repeated pressure loss, a suspected leak, an expansion vessel check, or any sensor or wiring inspection inside the boiler casing needs a Vaillant or Gas Safe registered engineer.