Heat pumps · Error codes · Joule
10Joule
10 on a Joule heat pump: Water Pressure low, < 0.8 bar
Short answer
On a Joule heat pump, 10 means: Water Pressure low, < 0.8 bar. The heat pump keeps running. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the Modul-AIR exhaust air heat pump
The manual says: Water Pressure low, < 0.8 bar.
On the Victorum exhaust air heat pump
The manual says: Water Pressure low (<0.8bar).
Is it safe?
| Does the heat pump stop? | No |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running.
What you can check
On the Modul-AIR exhaust air heat pump
- Read and note the code shown on the controller display, then contact your installer or service engineer.
- Check the heating system pressure gauge reading against the value in your handover documents (manufacturer commissioning values: typically 1-2 bar) and that the filling loop is closed.
- Joule-trained installer should check any filter or pressure action; the manual permits users only to replace the air filter.
On the Victorum exhaust air heat pump
- Read and note the code shown on the controller display, then contact your installer or service engineer.
- Check the heating system pressure gauge reading against the value in your handover documents (manufacturer commissioning values: typically 1-2 bar) and that the filling loop is closed.
What the engineer will check
- Manual 'possible solution': Increase water pressure.
- Check and restore system pressure via filling loop.
- Check for leaks and expansion vessel charge.
- Check water pressure sensor/switch and wiring.
Who to ask for: heating / plumbing heat pump installer.
Certification: None specific.
What you might notice
Sources
- Joule Modul-AIR All-E, Modul-AIR All-E with Green Comfort Module & Modul-AIR Aqua - Installation & Maintenance Manual ENG-0026-07 (UK/IE) ↗ · ENG-0026-07 · page 104 · Reviewed 23 September 2026
- Victorum Pre-Plumb & Victorum Compact Exhaust Air Heat Pump Installation & Maintenance Manual ENG-0014-8 ↗ · ENG-0014-8 · page 96 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026