Grundfos SCALA Instructions Manual page 15

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 is set too high. The
difference between the outlet
pressure and the inlet pressure
Yes
must not exceed 3.5 bar (51 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, for
example 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) There is a 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 pressure to a new setpoint
(maximum 3.5 bar (51 psi) + positive
inlet pressure).
Example: If the inlet pressure is 0.5 bar
(7 psi), the maximum outlet pressure is 4
bar (58 psi).
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.
15