Grundfos STP 2 fault 1E

What it means

Insufficient water flow below the minimum starting flow rate prevents pump start.

Likely causes

1. Insufficient water flow, below 0.5 l/min
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. Pipes routed under floor causing air traps
8. Solder joint heat damaging plastic pump components
9. Air pockets from incorrectly routed pipework
10. Additional outlet fittings on inlet pipework causing incorrect flow switch operation
11. Debris ingress into pump causing blockage or damage if strainer omitted

Where to start

1. Measure water flow rate
2. Inspect for airlocks in supply pipe
3. Purge all air from system