New motor but lower pressure

Strom · Jul 14, 2014

I had to replace my pump motor this past weekend. The old motor was 1 HP with a 1.4 safety factor. The new motor, although from a different manufacturer, has the same specs, 1 HP with a 1.4 safety factor. My concern is that the old motor would show 15 PSI on the filter pressure gauge. The new motor only shows 9 PSI. I've confirmed with two different pressure gauges.

Is there something I'm missing? Am I concerned about something that doesn't really matter?

JasonLion · Jul 14, 2014

That is very strange. It may or may not be a problem, but it is worth looking into further.

Do you see any air in the pump strainer basket?

Could there be a valve somewhere on the suction side of the pump that got moved so the flow into the pump is restricted compared to what it was before?

Strom · Jul 15, 2014

Thanks for the reply Jason.

There are no bubbles in the strainer. I also confirmed that the main drain and skimmer suction valves are open 100%. I'll borrow a clamp on amp meter from work and confirm the motor is pulling nameplate amps.

Sminor · Jul 15, 2014

Did you change the seal and check the impeller when you had it apart?

Strom · Jul 15, 2014

New seal installed and checked impeller. I was happily surprised by the lack of hair in the impeller.

(Wife and two daughters with long black hair.)

Isaac-1 · Jul 15, 2014

Are both motors rated for the same number of rpms?

Strom · Jul 18, 2014

Problem is solved and turned out to be a case of pilot error. The motor is dual voltage rated for 230 or 115 volt operation. It is shipped to run on 230. I read but misunderstood the instructions on how to set the motor up for 115 volt operation. The reason the pressure read low was due to supplying 115 volts to a 230 volt motor. Once the internal motor wiring was corrected, everything was back to normal.