Grundfos STP 2 fault 1D

What it means

Pump installed with non-vertical outlet ports affecting flow switches, preventing start.

Likely causes

1. Pump installed with non-vertical outlet ports (flow switches)
2. Entrapped air causing airlocks in supply pipe
3. Air not thoroughly purged from system
4. Air trapped in pump
5. Blocked strainers common on initial pump installation or new buildings due to jointing compounds, tapes, flux and debris flushed through system
6. Leak causing loss of tank air pressure
7. Low flow rates from cistern filling causing frequent pump cycling
8. Outlet positioned below mains inlet causing air ingress
9. Pipes routed under floor causing air traps
10. Solder joint heat damaging plastic pump components
11. Air pockets from incorrectly routed pipework
12. Additional outlet fittings on inlet pipework causing incorrect flow switch operation
13. Debris ingress into pump causing blockage or damage if strainer omitted

Where to start

1. Check orientation of pump outlet ports
2. Inspect for airlocks in supply pipe
3. Purge all air from system