Heat pumps · Error codes · Vokèra
Er20Vokèra · Vokera Aria (R410A, on/off)
Er20 on a Vokèra Vokera Aria: Flow switch
Short answer
On a Vokèra heat pump, Er20 means: Flow switch. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Flow switch.
Likely causes:
- Insufficient flow rate or system not purged; circulator broken or clogged; flow switch wiring (terminals 9-10).
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
What you can check
- Read and note the exact code shown on the controller display.
- Check the heat pump's breaker/isolator at the consumer unit is on.
- Read the system pressure gauge and report the reading to your engineer (manuals ask for more than 1 bar when cold).
- Check the filling loop valves are closed.
- Restart once via the controller (OFF then ON) as the manual allows; if the code returns, call an engineer.
What the engineer will check
- Insufficient flow rate or system not purged; circulator broken or clogged; flow switch wiring (terminals 9-10).
Sources
- Vokera Aria air to water heat pump - Installation & Servicing Instructions ↗ · 2009 (URL path) · page 29 (table); 35 (troubleshooting) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026