Possible Low Performing Pump

jim1504 · Postby **jim1504** » Mon 30 Mar, 2009 06:46

I have a 3/4 HP Pentair Whisperflow pump. I have been having a suction problem where the pump strainer basket will only fill halfway (other half air) after running for a sufficient period of time. After much diagnosis & testing I inadvertently discovered that if I remove the pump basket, the pump will fill completely with water. I have replaced the pump basket (my old one works fine in the my brothers pump ). There are no deformities inside the pump basket chamber. Does anyone know how I can check to see whether the pump is running at full capacity?

Postby **Me...** » Mon 30 Mar, 2009 08:44

I've never seen a clean basket (the right one anyways) impede flow. Removing and reinstalling the lid may have inadvertently fixed the lid seal?

A 3/4hp Whisperflow will do 60-70 GPM if installed with proper plumbing. One tool is a properly installed flowmeter. To really measure you need to know suction side gauge reading, pressure side gauge reading, voltage and amp draw. This allows you to calculate the head resistance the pump is working against and then use the manufacturers chart to see what flow you should be getting at that resistance.

jim1504 · Postby **jim1504** » Mon 30 Mar, 2009 14:57

I've tried going back & forth between basket/no basket & the basket impedes the flow every time. It sounds crazy I know. Thanks for the instructions on checking for the pumps flow rate. Since I dont have the pressure gauge, I might just try switching out my brothers 1.5 pump and inserting into my pump housing. Thanks again for the help!

Me... wrote:I've never seen a clean basket (the right one anyways) impede flow. Removing and reinstalling the lid may have inadvertently fixed the lid seal?

A 3/4hp Whisperflow will do 60-70 GPM if installed with proper plumbing. One tool is a properly installed flowmeter. To really measure you need to know suction side gauge reading, pressure side gauge reading, voltage and amp draw. This allows you to calculate the head resistance the pump is working against and then use the manufacturers chart to see what flow you should be getting at that resistance.

jim1504 · Postby **jim1504** » Wed 01 Apr, 2009 19:49

I installed my pump in my brothers system & it worked perfectly fine (he has a 1.5hp & I have a 3/4hp). I put my brothers pump into my system & had the same problem in that the air would not clear from the strainer basket (even when the strainer basket was removed). I did notice that my filter pressure rose to 35psi with his pump while mine was usually 20psi (he has the exact same pool filter).

A while back I tested my pump/housing for leaks by pressurizing it with a drain king. The filter psi levels went past 40psi. Seems like instead of rising to those levels, the excess presure should have been released to the pool. Is that what should have happened? I'm wondering if I possibly have a restriction in the return line.

Guest · Postby **Guest** » Thu 02 Apr, 2009 00:05

the air would not clear from the strainer basket

This would indicate a problem on the suction line. The pump is sucking air or is unable to suck enough water.

my filter pressure rose to 35psi (35 psi = 241 KPa) with his pump while mine was usually 20psi

If the pump is not able to draw enough water the pressure should actually be lower. Try compare pressure values on recirculate or with the cartridge element removed.

jim1504 · Postby **jim1504** » Thu 02 Apr, 2009 06:50

I tested all suction lines using a drain king for pressure. All were fine.

I was wondering if the filter pressure would rise to high levels if there was a blockage after the filter. Seems like a blockage after the filter would cause back pressure to the filter. I'll check the pressure without the cartirdge. Thanks for the help!

Pool User wrote:
the air would not clear from the strainer basket

This would indicate a problem on the suction line. The pump is sucking air or is unable to suck enough water.

my filter pressure rose to 35psi (35 psi = 241 KPa) with his pump while mine was usually 20psi

If the pump is not able to draw enough water the pressure should actually be lower. Try compare pressure values on recirculate or with the cartridge element removed.