New Pump Pentair Intelliflow 3HP issue running Polaris sweep

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At 3,450 rpm, 2100 watts suggests a flow of about 50 gpm and about 90 feet of head loss. If the pressure gauge is reading 10 psi, that's about 23 feet of head loss leaving the rest for the suction side, which is not possible without cavitation.

Something is off. The vacuum gauge can help diagnosis the problem. The vacuum gauge in the link will work. There might not be enough clearance for the gauge to screw in directly. You might need to rig a bit of tubing to get a reading.

There is a sticker on the pump strainer housing. What pump model number does it show?
 
Ok, I think that there is probably a suction side problem. At full speed, the pressure should be much higher.

If you put your hand in front of a return, how strong is the pressure?

If you only have two returns, the pressure at full speed should be super strong, especially if you have directional eyeballs.

Also, it might be a bad pressure gauge. Does it seem to move smoothly back to zero when off?

Maybe try a new gauge to be sure.
 
very little pressure on returns. of course i have never had much but it may be the same issue. i assume it was my crappy pump that i had.

will the gauge i posted work for the filter too? i have not paid too much attention but i think it does move slowly back to 0.
 
ok, could not find one locally so i ordered both from amazon. should be here tomorrow. hopefully they will arrive before dark. i am curious - what were you looking at with my pump model #?

thanks for everything and will update tomorrow if i get the gauges.
 
I wanted to make sure that it wasn't a Pentair IntelliFlo i1 - 011059, which has a smaller impeller and a limited hp.

Your pressure is way low at high speed. It should feel like a firehose out of the returns.

That points to a possible issue with the suction side. But I would think that the pump would be seriously cavitating. Serious cavitation sounds like rocks in a garbage disposal. But yours is not that loud.
 
OK thanks. just out of curiosity i switched over to the hottub for return and drain. the pressure only got to about 9psi. the pump was at 3100 and same power. now it concerns me i have an issue there too. based on what you said, if the hottub pipes were right the pressure would be higher. i guess that pressure gauge could be bad. although power usages was the same too.

i did not check the return pressure - dark and i just wanted to check that real quick.
 
Ok, I just listened with better sound. At full speed, it is excessively noisy and I do think that it is cavitating. Here are some power value ranges that I think you should be in at different speeds. I think that if you’re outside these ranges, you have a problem.

3450 rpm 2300 watts to about 3,000 watts.

3100 rpm 1,730 to 2260 watts.

2070 rpm 500 watts to about 700 watts.

I would suggest dropping the speed to about 2,100 rpm to see how that does.

Your plumbing really isn’t big enough to support rpm above about 2500 rpm.

You can probably run as low as 1,000 rpm as long as the skimmer action is ok. The Polaris booster pump only requires about 12 to 15 gpm to keep it fed with water.
 

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scottsams said:
OK, I will work on that. I will look into getting a vacuum gauge. What power would you expect? You mentioned 2100RPM but not 3100. Is it high? I will check returns and will post model number.

The bread trick. I have used that on sweating copper pipers. This one may need a Hoagie bun!

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will this gauge work?

HFS 2-1/2 Scientific
Click to expand...

question-
I got the gauge and it has a rubber nipple on top and it says to cut it after installing the gauge. looking at reviews on amazon, someone said to not cut the tip. do you know?
 
The nipple should be cut off to vent the gauge.

Try it uncut first to see if there is a difference.

Check vacuum and filter pressure and power at a few different RPMs to see what that shows.

I would not go above 3,000 RPM on your system because the plumbing is not big enough.

Also, be careful not to screw the vacuum gauge in too tight as the drain hole could crack.
 
Here are my readings. I have not taken main drain readings yet - still need to fix the pipe. I put the pressure gauge in and if anything, the pressure dropped 1 psi. It never got over 10 on all readings and was closer to 8. I cut the nipple off after these readings below on the Vacuum gauge and saw no noticeable difference. Let me know what you think.


RPMSkim VacSkim WattsHottub VacHottub Watts
3000-261476-251503
2070-16.5590-15608
1500-8267-7282
 
One quick update. It dawned on my my skimmer has some kind of plate in it that seems to restrict flow. There is a slide flap that can cover the whole and then a float. I pulled that out and checked again. vacuum seemed to stay the same but WATTS went up to ~ 1690 at 3000 RPM. Pressure rose to right at 10 PSI. After that I checked my returns of which I have 4. The two in the deep end closest to the pumps were quite strong. I'd say as strong as a hose open full. The two furthest away were much weaker. The one furthest away is missing the rotator so that could be part of that issue.
 
26" hg is about 29.5 feet of head. That's too high and likely to cavitate. It could just be the plumbing without any clogs. The pump is very strong and is too much at full speed, especially on just one line. With both skimmer and main drain open, you might be able to run at 3,000 rpm but there really isn't any reason to do so.

The benefit of a variable speed pump is running it as slow as possible. The power is a cube factor. At 1/2 the speed, the power will br about 1/8 (2^3 (actually closer to 2^2.65))

Your suction readings are a bit high. Moving the flap helped. Maybe a partially clogged line.

Once the main drain is included, you might get better flow.

Maybe try clearing the skimmer line. Usually putting a pump on the line to pull backwards can help.

For now, I would run the pump as slow as possible while still getting good skimmer action.

Are the skimmer and main drain 1.5" or 2"?

If the skimmer is 1.5" pvc pipe and about 50 to 80 feet long, the suction readings are plausible. However, if the line is 2", I suspect that it might be clogged.

How far from the pool to the pad?
 
skimmer and main drain are 1.5". i would guess that 50' would be max for both and probably less - straight line to pump is probably 30 ft if that. pad to the pool edge is roughly 20-25'. skimmer is only another 8' around the edge of the pool. pad is off deep end so straight line to main drain is about the same however obviously it is 8 ft down in the ground. or more. pool is 8' deep.

so i guess i overbought on pump? i was afraid of that. it is hard to find good help around here. i played phone tag with two pool companies and one no-showed on me so i went ahead and did the DIY route again which i did not want to do. my bad..
 
It's still a good pump. The good thing is that you can control the speed. Just run it as slow as possible while still getting good skimmer action.

You will save a lot of money vs your old pump and it will be very quiet.

Overall, not such a bad choice.
 
thanks. i just made some assumptions that i should not have. i had good intent and got impatient. when you say my pipes are too small, what is the normal size nowadays? 2.5?

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i am probably to the point i try another company - to see if i can find someone that will actually come out and understands the pressure/vacuum issues like you do. i really appreciate your help. you have taught me a tremendous amount.
 
Pipe size depends on the pool.

In any case, I would not use 1.5” on any in ground pool suction. I would use a minimum of 2”. How big depends on flow rates needed. In some cases, up to 3” pvc might be necessary.

For returns, I would also use 2” minimum.
 

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