Troubleshooting - Grundfos SQ Series Installation And Operating Instructions Manual

13. Troubleshooting

Fault
1. The pump does
not run.
2. The pump runs but
gives no water.
3. The pump runs at
reduced capacity.
4. Frequent starts
and stops.
10
Cause
a) The fuses are blown.
b) The GFI circuit breaker has tripped. Reset the circuit breaker.
c) No electricity supply.
d) The motor protection has cut off the
electricity supply due to overload.
e) The drop cable is defective.
f) Overvoltage has occurred.
a) The discharge valve is closed.
b) No water or too low water level in
well.
c) The check valve is stuck in its
closed position.
d) The suction strainer is closed.
e) The pump is defective.
a) The drawdown is larger than antici-
pated.
b) The valves in the discharge pipe are
partly closed/blocked.
c) The discharge pipe is partly choked
by impurities (iron bacteria).
d) The check valve of the pump is
blocked.
e) The pump and the riser pipe are
partly choked by impurities
(iron bacteria).
f) The pump is defective.
g) Hole in discharge pipe.
h) The riser pipe is defective.
i) Undervoltage has occurred.
a) The differential of the pressure
switch between the start and stop
pressures is too small.
b) The water level electrodes or level
switches in the reservoir have not
been installed correctly.
c) The check valve is leaking or stuck
half-open.
d) The supply voltage is unstable.
e) The motor temperature is too high.
Remedy
Replace the blown fuses. If the new fuses
blow too, check the electrical installation
and the drop cable.
Contact the electricity provider.
Check for motor/pump blockage.
Repair or replace the pump/cable.
Check the electricity supply.
Open the valve.
Increase the installation depth of the pump,
throttle the pump or replace it with a smaller
capacity model.
Pull the pump and clean or replace the
valve.
Pull the pump and clean the strainer.
Repair or replace the pump.
Increase the installation depth of the pump,
throttle the pump or replace it with a smaller
capacity model.
Check and clean or replace the valves as
necessary.
Clean or replace the discharge pipe.
Pull the pump and clean or replace the
valve.
Pull the pump. Check and clean or replace
the pump, if necessary. Clean the pipes.
Repair or replace the pump.
Check and repair the piping.
Replace the riser pipe.
Check the electricity supply.
Increase the differential. However, the stop
pressure must not exceed the operating
pressure of the pressure tank and the start
pressure should be high enough to ensure
sufficient water supply.
Adjust the intervals of the electrodes/level
switches to ensure suitable time between
the cutting-in and cutting-out of the pump.
See installation and operating instructions
for the automatic devices used. If the inter-
vals between start/stop cannot be changed
via the automatics, the pump capacity may
be reduced by throttling the discharge
valve.
Pull the pump and clean or replace the
check valve.
Check the electricity supply.
Check the water temperature.