Grant Aerona R290 fault 6

What it means

Pump block protection has activated; pump will automatically re-start after 5 seconds.

Likely causes

1. Pump rotor blocked or stuck
2. Impurities in pump
3. Poor pump performance
4. Fuse is burnt out
5. Connection to PCB is loose or disconnects
6. Pump failure
7. Too low voltage
8. Pump rotors are stuck
9. Gas in the pump
10. Inlet pressure too low
11. Flow regulators or restrictors fitted in circuit
12. Valves not fully open causing flow restriction
13. External electrical isolator switched to OFF position
14. Heat pump switched OFF at the controller
15. No demand from heating system controls
16. Outdoor temperature too high to call heat pump on (weather regulated zones)
17. Active error code present on controller
18. Outside air temperature at or below 6°C
19. System water temperature at or below 6°C
20. Outdoor temperature too high for weather compensated zones to call heat pump
21. Active error code on controller display
22. Insufficient flow rate through primary circuit
23. Pump fault or blockage causing low flow
24. Wire disconnection or wiring error between the heat pump, wiring centre and touch screen display
25. Fuse on the hydraulic module PCB may have failed
26. Fuse on the Smart Controller wiring centre PCB may have failed
27. PWM circulating pump not modulating correctly
28. Blockage or air in primary circuit
29. External electrical isolator switched OFF for extended period during cold weather
30. Outdoor air temperature (T4) below 7°C combined with low return (TA) or flow (TB) water temperature below 6°C

Where to start

1. Check pump rotor for free movement
2. Inspect for impurities/debris in pump
3. Check inlet water pressure