Variable Speed Booster Pump Repair London

Typical variable speed booster faults

Pressure hunting — the outlet pressure oscillating around the set point — is the signature variable speed complaint, usually caused by a failing transducer, an incorrectly configured control loop or an accumulator that has lost its pre-charge and no longer damps the system. Other frequent faults are drive trips on overcurrent or overtemperature, cascade control that fails to bring the second pump in under load, and sets that were commissioned to a set point nobody has reviewed since the building changed use.

• Pressure hunting and oscillating set point
• Transducer drift and sensor failure
• Drive overcurrent, overtemperature and earth faults
• Cascade and duty rotation control faults
• Accumulator pre-charge loss reducing stability
• Set point and ramp rates left badly configured

Diagnosis starts at the drive

Every variable speed set logs its faults, and that log is the fastest route to the cause. We download the fault history, compare the transducer reading against a calibrated gauge, check the set point against the building's actual requirement, and review the ramp and PID parameters before we touch the hydraulics. Only once the control side is proven do we look at the pumps themselves, running each in turn under load with current measured against the nameplate.

• Drive fault history downloaded and interpreted
• Transducer verified against a calibrated gauge
• Control parameters reviewed and corrected
• Pumps run individually under load with current measured

Getting the energy benefit back

A variable speed set that is hunting, running at full speed continuously, or cascading both pumps when one would do is costing far more to run than it should, and the extra wear shows up as premature seal and bearing failures. Correcting the control configuration typically restores both the energy performance and the pump life. We record the running profile before and after so you can see the change rather than take it on trust.

Repairs, parts and follow-up

We repair the common Grundfos, Wilo, Lowara, DAB, Stuart Turner, Ebara and Armstrong variable speed sets and fit manufacturer parts — transducers, drives, control boards, seal kits and chamber stacks. After the repair we reset the accumulator pre-charge, re-commission the set to a documented set point, and issue the figures in writing. Where the set is in a block or commercial plant room we recommend a six-monthly maintenance interval to keep the control side honest.

• Manufacturer parts for the common VS ranges
• Accumulator pre-charge reset as part of the repair
• Documented recommissioning figures issued
• Six-monthly maintenance recommended for busy sites