F.022 on a Glow-worm GeniaAir: No/insufficient water in the product or the water pressure is too low
Short answer
On a Glow-worm heat pump, F.022 means: No/insufficient water in the product or the water pressure is too low. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: No/insufficient water in the product or the water pressure is too low.
Part involved: No/insufficient water in the product or the water pressure is too low.
Likely causes:
- Insufficient/no water in the product; fault in the electrical connection for the water pressure sensor; cable for the pump/water pressure sensor loose, not connected or defective; water pressure sensor defective; pump operation interrupted; solenoid valve of automatic filling device defective; internal expansion vessel defective.
- Glow-worm trade page: Low water pressure in the system The water pressure in your system is below the normal range of 1 to 1.5 bar, loose, disconnected, or faulty wiring for the pressure sensor, water pressure sensor faulty, expansion vessel faulty.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: likely clears when pressure restored (not stated in HPIM 7 doc).
Manual reset: not normally required.
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). Read the system pressure (display/pressure gauge; normal cold 1.0-1.5 bar). Ask your installer to top up and find the cause of the pressure loss; check the filling loop is closed and look for visible leaks.
What the engineer will check
- Fill the heating installation and check product/system for leaks; check/replace wiring harness and cables to pump and pressure sensor; check/replace pressure sensor; check automatic filling device; check/replace internal expansion vessel.
Who to ask for: Vaillant-trained heat pump installer/engineer (MCS-certified installer).
Certification: MCS installer certification; Vaillant product training recommended.
What you might notice
Sources
- GeniaAir Appliance Interface installation and maintenance instructions ↗ · 8000043014_01 · page HPIM 7 8000043014_01 p.30 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026