Grundfos SCALA Installation And Operating Instructions Manual page 13

Fault
4. System
overpressure.
5. You can reset the
pump, but it runs
only for a few
seconds.
6. You can reset the
pump, but it starts
repeatedly,
immediately after
stopping.
Cause
a) The setpoint has been set too
high. The difference between the
outlet pressure and the inlet
pressure must not exceed 4 bar
Yes (58 psi).
Example: If the required outlet
pressure is 5 bar (73 psi), the
minimum inlet pressure must be 1
bar (14.5 psi).
b) The maximum pressure has been
exceeded - the inlet pressure is
Yes
higher than 6 bar, 0.6 MPa (87
psi)
c) The maximum pressure has been
exceeded - equipment elsewhere
in the system causes a high
Yes
pressure at the pump (e.g. water
heater or defective safety
equipment)
a) Dry running or water shortage
Yes
b) The inlet pipe is blocked by
Yes impurities
c) The foot or non-return valve is
Yes blocked in closed position
d) Leakage in the inlet pipe
Yes
e) Air in the inlet pipe or the pump
Yes
a) The internal non-return valve is
No defective or blocked in completely
or partly open position.
b) The tank precharge pressure is
No not correct.
Remedy
Reduce the setpoint to 4 bar (58 psi)
+ positive inlet pressure.
Check the inlet conditions.
Check the installation.
Check the water source, and prime
the pump.
Clean the inlet pipe.
Clean, repair or replace the foot or
non-return valve.
Repair the inlet pipe.
Prime the inlet pipe and the pump.
Check the inlet conditions of the
pump.
Clean, repair or replace the
non-return valve.
Adjust the tank precharge pressure to
70 % of the required outlet pressure.
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