In-Ground Pool Pump Feed Problem


I realize this is not directly related to the purpose of this group, so if you know of a better place for me to ask, please let me know.
We have a problem with our Pentair-WhisperFlo pool pump. It is not able to fully prime, even with addition of water into the pump body directly (via the volute/strainer basket). It seems able to draw about 1/2 the amount it needs to fully prime and operate. We have replaced the pump impeller, and have tried to clear the inlet line (1 inch PVC pipe) through pressure from a garden-hose expansion nozzle from both directions. Nothing has worked. We believe there is probably a blockage/obstruction of some kind in the pipe between the pool and the pump (perhaps a tree root that has gradually penetrated the pipe).
Does anyone have any ideas of what else we can do to find out if there is an obstruction in this inlet pipe? Our resources are quite tight, so hiring a plumber to come in with specialized/optical equipment would be beyond our reach at this point.
Thanks for any suggestions you may have.
Lee
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Check the conditions of any O-rings on the pump/filter. If they are flattened and not round, the system might be suctioning air and not priming.
For checking the pipe: Can you run a wire snake (electrician's snake) into the pipe?
Oh, your post is on topic.
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Damn. Didn't you know if you own a pool you are supposed to be rich? <g>
Wish I knew the answer to your problem. I'll be watching this thread to see if anyone has any good ideas.
I just bought one of those Pentair-WhisperFlo pumps from Leslie Pools. They are supposed to install it this week. Did you have any other issues with your pump and how many hp does yours have?
Jim
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Do you have a break in the inlet pipe? If it's sucking air it may not prime. If you can get it to prime, are there still bubbles on the inlet side?
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I have a WhisperFlo. For other readers, this unit has a clear plastic lid so you can see any cavitation. A 1 inch inlet might be insufficient. What hp is this pump? What was the original hp? If you are now running too much pump, a solution might be to install a ball valve on the outlet and dial it down a bit.

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Have you checked to see if air might be coming from the skimmer? The flapper on the skimmer can sometimes become partially obstructed, letting the pump drain the skimmer cavity before it can refill. A second possibility might be if you have a hot tub. A bad air valve might be permitting air to enter the pump. I'd check, and if there's an electric valve operator for a spa, make sure that the motor is set to totally close off the valve and that it's not partially open.
Micajah
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Did you open the bleed port on the filter? It can take forever to get all the air out of the pump if the filter is also full of air. If your suction line is cracked underground you should be losing pool water when the pump is off. Above ground you should be able to hear the leak. A piece of 1/2 "pipe held up to your ear and the other end tracing the joints on the fittings helps hear the air leak.
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As others have suggested run a snake down it. You do need to get all the air out. If it is able to draw any water at all then it will pump what it can. The fact that there is a partial restriction does not prevent it from priming.
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Agree with John regarding the pipe size. I don't know how small a pump Pentair makes in that line, but 1" line for a pool is unusual. More typical is 2". Also agree with gfretw, regarding opening the bleed air valve on the filter. I would think it could take a lot longer without the bleed air valve open, but eventually it should still get all the air out.
How many hp pump? How old? Was it working OK prior to the sudden problem?
What happens if you set the valve to waste, so water is not returning to the pool and just being pumped out the short waste hose? Will it quickly prime and run OK then?
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On Aug 30, 8:39am, snipped-for-privacy@optonline.net wrote:

Also, check the o ring on the pump strainer basket. If it has any cracks or looks worn out, replace it. And make sure to use some teflon grease to lubricate it. Air leaks at this spot are very common.
And for more help, you can't beat the pool and spa forum which you can find on the internet
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wrote:

Agree with John regarding the pipe size. I don't know how small a pump Pentair makes in that line, but 1" line for a pool is unusual. More typical is 2". <snip>
== The lowest is a 1/2 hp and all Whisperflo pumps are for 2" pipes.
Jim
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Jim
Is that Pentair a two spend motor?
Locally, the power co. gives a rebate for the two speed motors. Last I looked they did anyway -- $200.00
Claims to be 40% more efficient.
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raises.
Jim
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On Mon, 30 Aug 2010 05:39:26 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

OP said he changed the impeller. He should've also changed a seal at the same time behind the impeller (iirc).
That seal will leak water and drip from the motor shaft. Perhaps cavitation and no proper priming.
OP went missing...
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You know this may seem obvious, but what does it do if you run your multivalve to waste? I was thinking you maybe looking at this from the wrong end.
Also, if it's a in-ground pool, why isn't that a 2" pipe?
Jim
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Thanks to all of you that have replied to my question. First, I have to agree with JimT:
Damn. Didn't you know if you own a pool you are supposed to be rich? <g>
As the old saying goes: The only difference between men and boys is the price of their toys. and The definition of a pool is: a hole in the ground surrounded by concrete into which you endlessly pour money. [same applies to boats too]
In order to keep it short, I omitted some of the other things we've done to try and correct this problem. Also, I incorrectly said the inlet pipe was 1 inch PVC... It is 2 inch; typo on my part. The pump is 2 HP, 240 volt. The pump is 4 years old and it was working fine until a little over a week ago when I discovered the problem while switching from our Pool-Vac to manual, to clean some bottom debris from a wind storm we had a day earlier.
The O-rings are all good and we've cleaned and sealed them with silicone lube to ensure a good seal.
We've tried to run a plumber's snake through the pipe from both ends with limited success. There's a 90 degree elbow a couple of feet from each end of the inlet pipe; our snake is fairly light duty and it winds-up on itself as it goes through the elbow, so were not sure how far beyond the elbow the snake actually proceeds. Weve not noticed much in terms of debris floating out as we withdraw the snake.
We've tried it with the bleed-air port both open and closed and the skimmer basket has been cleaned and checked for correct operation of the flapper valve. Weve tried to get it to operate with the skimmer basket removed too. Weve also tried with the waste valve both open and closed for about 5 minutes each with no positive result.
Given the clarification above, any other thoughts you may have would certainly be appreciated. As trad suggested, we will search for the pool and spa forum and post our situation there too.
Thanks again to all of you that took the time to respond to our question.
Lee
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Thanks to all of you that have replied to my question. First, I have to agree with JimT:
Damn. Didn't you know if you own a pool you are supposed to be rich? <g>
As the old saying goes: The only difference between men and boys is the price of their toys. and The definition of a pool is: a hole in the ground surrounded by concrete into which you endlessly pour money. [same applies to boats too]
In order to keep it short, I omitted some of the other things we've done to try and correct this problem. Also, I incorrectly said the inlet pipe was 1 inch PVC... It is 2 inch; typo on my part. The pump is 2 HP, 240 volt. The pump is 4 years old and it was working fine until a little over a week ago when I discovered the problem while switching from our Pool-Vac to manual, to clean some bottom debris from a wind storm we had a day earlier.
The O-rings are all good and we've cleaned and sealed them with silicone lube to ensure a good seal.
We've tried to run a plumber's snake through the pipe from both ends with limited success. There's a 90 degree elbow a couple of feet from each end of the inlet pipe; our snake is fairly light duty and it winds-up on itself as it goes through the elbow, so were not sure how far beyond the elbow the snake actually proceeds. Weve not noticed much in terms of debris floating out as we withdraw the snake.
We've tried it with the bleed-air port both open and closed and the skimmer basket has been cleaned and checked for correct operation of the flapper valve. Weve tried to get it to operate with the skimmer basket removed too. Weve also tried with the waste valve both open and closed for about 5 minutes each with no positive result.
Given the clarification above, any other thoughts you may have would certainly be appreciated. As trad suggested, we will search for the pool and spa forum and post our situation there too.
Thanks again to all of you that took the time to respond to our question.
Lee
== Please let us know how it turns out.
Jim
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2 HP is probably oversized for a 2 inch pipe, but since this is a new problem, that isn't the issue.
Since this happened when you switched the pool vac to manual, I'd think air leak in that valve.
To check for obstructions, if you have some suction, I've tied a nut [any small object which will negotiate the bends] on a strong [you probably don't want this to break] nylon line and let the pump suck it from the skimmer. If you get through, there is probably no obstruction; or you can tie a larger nut on when it reaches the strainer and pull back through the skimmer.

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wrote:

Another possibility. The problem occured when trying to manually vacuum the pool. There are a variety of ways to manually vacuum a pool, but one of the most common is to attach the vacuum to one of the skimmer suction lines. And to increase the vacuum, it's also common to shut off some or all of the other suction lines. If this was done and with a 2hp pump, it could create a lot of suction. The problem could come if the pool was installed using flex PVC pipe as opposed to rigid. Around here, NJ, it's common to use regular PVC at the pool pad, then transition to the flex underground. Flex PVC has a much lower rating for suction than it does for pressure. Meaning with too much suction in can possibly collapse. Last year a friend had a section of flex PVC that had collapsed and was leaking, but in that case it appeared most likely it was due to being damaged when backfilled. Still, it took 3 years to fail. We located it by using an air compressor to pressurize the line and got lucky when water and air started bubbling out of the ground at the leak. Got even luckier when the bad section was not under the stamped concrete pool deck.
Also, now that I'm thinking about it, how is this thing plumbed? Is there only one suction line at the pump? On my pool pad there are three seperate lines appearing with valves, two for skimmers and one for the bottom drain. Meaning at the eqpt pad I can select from the various suction lines going to the pump, it's not just a single line.

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