MQ 3-45

Common issues

• Diaphragm tank pre-charge loss causing the pump to short-cycle
• Pressure sensor or electronic control fault causing erratic on/off behaviour
• Motor overheating from a dry-run condition
• Mechanical seal leakage
• Cavitation or reduced output from an inadequate or restricted suction supply

Inspection checklist

• Check cycling frequency - excessive on/off switching usually indicates lost tank pre-charge
• Check discharge pressure against the set point
• Check for leaks at the seal and pipe fittings
• Test dry-run protection function
• Check the control board/display for any fault indication
• Check suction supply pressure and strainer condition

Service intervals

Critical spares

• Complete pump cartridge/motor unit (this series is largely a sealed replaceable cartridge rather than a field-rebuildable pump)
• Pressure sensor
• Non-return valve
• Diaphragm tank (pre-charged type)

Safety

• Electrical unit installed near water - ensure correct earthing and RCD/GFCI protection on the supply circuit
• Pressurized potable water system - depressurize before opening any fitting
• Must not be allowed to run dry for an extended period - this can damage the seal and overheat the motor

Class survey

Domestic freshwater systems are generally a low class-survey priority; where checked, it is usually for potable water system hygiene and cross-connection prevention rather than as classified machinery. Typical wear-limit figures have been left out here since this is a sealed cartridge-type unit without generic field-measurable clearances.