20
6.4.2
– Troubleshooting
SYMPTOM
POSSIBLE CAUSE
ANALYSIS
Pump stopped, no
power
Power supply interrupted
Check the power supply.
Attach external power control if necessary.
Fuse tripped or circuit
breaker opened
Repair short-circuited wire. Repair loose contact.
Check for the properly rated fuse.
Check pump motor and lead.
Pump stopped, power
supply present
Thermal switch has
actuated
Reduce ambient temperature.
Clean blocked or slow rotating pumps.
Pump does not start
Open air vent screw and unlock shaft. Clean pump.
Increase speed/set point.
Replace pump.
Noisy Pump
Cavitation sounds
Air in pump
Open bleed screw and vent pump. Vent and top up system
with water.
Check expansion tank.
Install air separator.
Cavitation sounds
Increase inlet pressure.
Reduce temperature.
Throttle back pump.
Reduce speed.
Resonance noises
Use sound insulation material between the pump and surface
to reduce resonance noise.
Install expansion joints.
Install fixture to change system’s natural frequency.
Adjusts pump speed.
Replace pump/motor.
Knocking from foreign
bodies in the pump/or on
valve
Turn valve around if installed incorrectly.
Clean impeller
Adjust valve pressure.
Adjust valve spring.
Replace pump.
Noise From Radiator
Excessive pressure passing
the thermostatic valve
Reduce the speed setting. Flow decreases will reduce system
pressure and eliminate the noise.
The radiator is not
giving off any heat
The thermostatic valve is
jammed or blocked.
Shut off all other radiators in the system, and set the pump at
maximum speed. Once the blockage has been dislodged,
reopen the radiators and adjust pump to original speed
setting.
Pump generates little
or no output
Dirty impeller
Open pump and clean the impeller
Note: Close isolation valves if present
Suction port blocked
Open pump and clean housing
Note: Close isolation valves if present
Dirty strainer
Clean Strainer
Air in the pump
Switch off pump and open bleed screw to vent
Pump at lowest/medium
speed level
Set pump to the next higher speed level.
