Just as with single speed pumps, maintenance of variable speed pumps starts at the strainer, or hair and lint pot.

This has been made much easier on the newer units where the clear lid enables service professionals to view the basket and inspect for leaves and debris.

Debris that builds up in this basket will begin to block the flow of water to the pump which can lead to inadequate circulation and sometimes pump failure.

The following procedures have been adapted from Pentair Pool Product’s Intelliflo variable speed pump manual.

Pump Failure

This is often related to a priming issue, such as an air leak in the suction, not enough water, or if the pump completes priming too early and there is still air in the housing.

• Check suction piping and valve glands on any suction gate valves.

• Ensure that the lid on the pump strainer pot and the lid gasket are both in place.

• Check the water level to be sure the skimmer is not drawing air.

• Be sure the suction lines, pump, strainer, and pump volute are full of water.

• Try adjusting the priming range to a higher or lower setting

• Check and clean pump strainer pot.

• Check that the pump strainer gasket is not defective and replace gasket if necessary.

Reduced Capacity and/or head

This may be caused by air pockets or leaks in the suction line.

• Check suction piping and valve glands on any suction gate valves.

• If the problem is a clogged impeller, turn off electrical power to the pump.

• Remove the bolts that hold the housing (strainer pot/volute) to the seal plate.

• Slide the motor and seal plate away from the volute.

• Clean debris from impeller. The issue may also be that the strainer pot is clogged.

Inadequate Circulation

• Check the filter or pump basket and clean as needed.

• Ensure that the suction/discharge piping is the correct size.

• The speed may be set too slow for proper filtration cycle.

Electrical Problem

This could appear as a “Low Voltage” alarm or as an “Over Heat” alert.

• Check voltage at motor terminals and at panel while pump is running.

• If this is low, see wiring instructions or consult power company.

• Check for loose connections.

• Check line voltage; if this is less than 90% or more than 110% of rated voltage consult a licensed electrician.

• Increase ventilation.

• Reduce ambient temperature.

• Tighten any loose wiring connections.

Motor runs too hot

• Turn power to motor off.

• Check for proper voltage.

• Check for proper impeller or impeller rubbing.

Mechanical troubles and noise

• If the pump motor is running but with a loud noise, it may be due to poorly supported suction and discharge piping.

• Ensure the unit is securely mounted on a concrete platform for quietest performance. If there is foreign matter such as gravel in the impeller, disassemble pump and clean the impeller.

• For cavitation, improve suction conditions; increase pipe size; decrease number of fittings; increase discharge pressure.

• For speaking noise, especially evident at pump startup or slow down, inspect the motor slinger and motor shaft seal behind the slinger (NOT the pump’s mechanical seal).

• Apply lubrication to the motor shaft rubber seals.

Pentair’s Intelliflo, VSP