I.200 on a Glow-worm GeniaAir: Low pressure in the decoupled brine circuit (building circuit) - systems with decoupled brine circuit
Short answer
On a Glow-worm heat pump, I.200 means: Low pressure in the decoupled brine circuit (building circuit) - systems with decoupled brine circuit. The heat pump keeps running. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Low pressure in the decoupled brine circuit (building circuit) - systems with decoupled brine circuit.
Part involved: Low pressure in the decoupled brine circuit (building circuit) - systems with de.
Likely causes:
- Pressure loss in the building circuit due to leaks or air pockets; pressure sensor defective.
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running.
Resetting itself: clears when condition resolved / engineer resets.
Manual reset: engineer resets (Installer level > Reset > Reset maintenance message).
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). Read the heating system pressure on the display (Menu > Live Monitor > building circuit pressure) or the pressure gauge: it should be about 1.0-1.5 bar when cold. Vaillant's operating instructions say to inform your competent person so that they can top up the heating water. Check the filling loop valves are closed and look for visible water leaks or a dripping pressure-relief pipe.
What the engineer will check
- Check for leaks; top up and purge; check pressure sensor and wiring.
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.29 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026