Pentair Intellilflow Variable Speed Pump Priming Problem

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PoolEngineer

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Apr 4, 2012
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I have had a pool for over 10 years. Last season I purchased a brand new Pentair Intellflow Variable Speed Pump Part # 011018 which was just new on the market at that time.

I installed it in my existing plumbing and almost immediately had a problem with sporatic priming alarms.

I use the programming function on the pump to run the pump during the day over a range of cycles and then keep it off overnight. Usually (but not 100% of the time) when the pump starts up for the first time the next morning it faults out with a priming alarm different than what the manual says is the way the alarm should function.

I think the main problem is that the pump leaks at the lid causing air to suck in very slowly when the pump is off. I have tried new seals, tighter clamping but I cannot stop this from happening.

So after being off all night, the pump starts up at 1800 RPM for 3 seconds as stated in the manual. It then ramps up to Max Speed and immediatly faults out on a Priming Dry Alarm. Somtmes this happens immediately when the speed ramps up, while other times it takes up to 5 or 10 seconds to alarm out. I then hit the alarm reset, retart the pump and it goes through the priming cycle again just fine starting up with full flow within 10 to 15 seconds. Note that the pump never ran the entire 5 minutes of the maximum primng time setting when it faults out.

If i disable the prime feature, the pump starts up just fine in high speed, however since I want the speed to run slow (ie 1500 rpm) you cant start up at 1500 RPM and expect it to prime so the system is kind of f**d.

I have talked to pentair, and talked, and talked, and service man came to the house. Their service is the most insulting I have ever seen:

1st insult - what do you expect when you buy the pump from an online pool store instead of from a store front place ! They made it sound like they shouldnt honour the warranty even though their service management said that the warrently is totaly valid. Idiots!

2nd insult - the pump has too many restrictions on the suction side - namely 4 x 90 degree elbows. Even though the pump can start and run without cavitation.

3rd insult - one of the 3 lines coming from the pool to the pump is 2" above the pump inlet because of the space a 3 way valve needs - they claim that this causes air to be in this line even though there is a check valve behind this.

I suspect that there is a sensitivity problem in how their software detects a dry prime condition. I mean it shuts off in just a few seconds after trying to start the pump - not minutes later. No pump can possibly be always up to prime in 3 seconds.

Has anyone seen this problem? Any ideas? Im about to throw this $1000 piece of **** out the door.
 
Oh a few other details:
I can uninstall the pump and put it right beside the pool with a pipe straight down into the water. Same thing - if its left overnight it faults out with dry prime alarm the next day. So much for my piping system and their lame excuse.
 
Welcome to TFP!

I agree with your analysis, none of those points about the plumbing would make any difference that matters here.

I suspect that the pump strainer basket lid does not leak. Variable speed pumps tend to collect a fairly large bubble of air in the pump strainer basket when they have been running for several hours on low speed. You can tell if the lid is leaking, or air is simply accumulating while on low speed, by turning the pump off after filling the strainer basket with water while on high speed. If the bubble returns with the pump off and the basket starting full, then there is an air leak. If the bubble only returns when running on low speed, then it is air coming out of solution due to low pressure in the pump strainer basket (which is normal and unavoidable).

I can suggest a couple of things that might help you work around the priming problem. None of these work every time, but hopefully one will work for you.

The first option is to run the pump on high speed for a short period at the end of the regular run time. That will clear out any air in the pump strainer basket and should allow the pump to prime correctly the next morning.

Another approach is to play with different settings of the max priming flow/speed. Often by lowering the pump speed/flow used during priming you can shift the timing so that the alarm doesn't happen before proper priming is achieved. Setting the up does take some trial and error.
 
To Admin
Thank you for your response. In order for the pump to prime fully (as defined by evacuating all the air from the strainer) I find that I need a max speed setting of at least 2500 RPM. Once filled, I can drop the speed down to about 1750 without much air accumulating over a typical run time of 2 hours. However, even priming at 2500 RPM causes the alarm to happen the same way.

I guess what I did not try is the approach where I intentionally allow some portion of air in the basket at the time it switches from priming to operating. Ill try that tomororw.

I am perplexed as to why air accumulates in the system at lower speeds - ie 1250 rpm. I have check valves in the supply lines and have recently redone the plumbing to make sure that there were no leaks. My assumption has been that air must be sucking in through the cover.
 
Air will accumulate in the pump strainer basket at lower speeds even if there isn't an air leak. Of course it will do so more quickly if there is an air leak.

The reason this happens is lightly technical. Basically there is always some air dissolved in the water (gasses dissolve in water just like salt does). The amount of air that can dissolve depends on the pressure. At high pressures more air dissolves. The pool will be at (or at least very close) to equilibrium, where as much air as can dissolve at standard outdoors air pressure will be dissolved in the water. However, inside the pump strainer basket the pressure is lower. The pump is pulling water out of the strainer basket, creating a pressure lower than standard pressure. At this lower pressure, less air can dissolve in the water, so some of it will come out of solution and slowly accumulate in the pump strainer basket.

At higher speeds the pump is able to clear this gas out of the pump strainer basket (or at least nearly all of it) during normal operation. Basically there is enough turbulence that it eventually gets pulled down into the rest of the pump. But at lower speeds there isn't enough turbulence to pull all of the air out of the strainer basket, so it accumulates. The total amount that accumulates depends on the speed. Even at low speeds the pump is able to draw in some of the gas, especially if the air accumulates enough that it is low down near the inlet.
 
Admin

I understand your dissolved air disucssion. What I do not understand is why after the pump has been shut off (with basket full of water), and with check valves between the pool and the pump, the basket drains below the inlet port level, almost to the very bottom of the trap. This would amost indicate to me that water is being siphoned out of the system between the outlet of the pump and the pool.

On the outlet side of the pump, the piping goes up a few inches and enters a large cartidge filter system. The water leaves the filter below the inlet port and is piped over to the heater which is maybe 3 or 4 inches above the inlet to the filter. However, the highest point on the dome of the filter is well above this pipe that goes through the heater and returns to the pool. Is it possible that I just need to make a loop in the outlet pipe coming out of the heater but before the pool where the pipe goes up above the highest level of the filter? Would this stop the pump basket from siphoning out?
 
PoolEngineer said:
I understand your dissolved air disucssion. What I do not understand is why after the pump has been shut off (with basket full of water), and with check valves between the pool and the pump, the basket drains below the inlet port level, almost to the very bottom of the trap. This would amost indicate to me that water is being siphoned out of the system between the outlet of the pump and the pool.
Click to expand...
Air will not normally enter a pool plumbing system unless there is a way for it to get in. So more than likely, you have an air leak somewhere and since you have check valve on the suction side, it is most likely the pump lid and/or the drain plugs.
 
Mas985
So if there is an air leak, and check valves are present, and no water is visually leaking out of the system, are you saying that the air leak allows the water to siphon out of the system through the pump and the filter back to the pool? If this is the case, from my previous post, would having a pipe loop higher than the filter stop this?
 
PoolEngineer said:
So if there is an air leak, and check valves are present, and no water is visually leaking out of the system, are you saying that the air leak allows the water to siphon out of the system through the pump and the filter back to the pool?
Click to expand...
Yes. Air enters the pump basket displacing the water and allowing it to run out the returns. Remember too, that on the suction side of the pump, the pressure is below atmospheric pressure so air leaks into the pump but water will not leak out.


If this is the case, from my previous post, would having a pipe loop higher than the filter stop this?
Click to expand...
No. The water will still siphon out. The only way to stop it is to fix the air leak.
 
I wonder if there might be an air leak on the filter's o-ring. It's unusual that the pump basket is losing water, and I'm certain that this is the problem with the priming. As a one speed pump apparently functioned fine before, this is probably because that old pump was able to keep up (at full speed) with the leak issue and acheive prime. Just because you don't see a water leak doesn't mean there isn't an air leak. Water is much denser than air, and this is probably a suction leak that is one-way. When was the last time you changed/lubed your filter's o-ring? BTW, is there a check valve between the pump and the filter? Our filter level when full is about 2.5 feet above the pool's water level, but I've not observed it losing much water when the pump shuts off. I have a check valve between the pump's outlet and the filter inlet, which may explain why the filter doesn't lose water. But in addition, if there is no leak along the line, there really shouldn't be a source of air.
 

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I have the same pump, and i have the same problem!!!!! low speeds I get air in the pump strainer, that ends up in filter, and filter fills up to the multi valve, when I turn the pump off the air in the filter goes back to the pump strainer, pool guy dose not care, and has stoped coming to try to fix it. He says to run pump at higher speed. This is BULL!!!!!
 
I cleaned and lubed the filters O ring at the start of this season a couple of weeks ago. I inspected the O ring and there are no nicks or bad spots on it. The pump O ring is another matter. Its my opinion that the cover and sealing system on this particular pump is the worst I have ever seen. The cover seems to lock in 1/4 turn so its is a very coarse adjustment to tighten the cover. The O ring looks good but I suspect that right from the new state the thickness of the O ring (by design) is too thin. Regardless of how tight the cover is, when you have heavy suction on the pump you actually see air seeping in through the cover and migrating along the underside of the cover to the dome. Furthermore, if you are runnng the pump in high speed with maybe 20 psi pressure on the filter and stop the pump, water always spits out of the cover for a quick second. I never saw this with my good old pump.

So I believe the problem with the Pentair pump is 2 fold:
1) The seal on the cover is sub-par - it really does not do an effective job of preventing air from entering the system - especially when the pump is off and when there is no water on the inside of the basket directly beside the seal.
2) The priming function on this pump design is flawed. Whatever the sensing mechanism is to prevent dry running, the sensing approach does not wait for a period of time (not presettable through user input) before it kicks the pump out on safety dry pump alarm. It can shut off the pump in as little as 3 second after the motor is powered on which really does not give the system enough time to build suction even if the water level in the basket is very low. If all they did was wait 10 to 15 seconds after the pump was powered on before they paniced and shut if off on dry alarm, I would not have a problem. The idiots over at Pentair do not acklowledge this flaw and instead make stupid claims about pipe size and the fact that the highest point of my suction pipe is 2" above the pump inlet - then the field service guy the sent over is a complete idiot. His answer - what do you expect from a pump that you buy from an 'Online retailer' you should only buy their pump from a strore front operation - even though their service department declared the warrenty fully in effect!

Pentair is NOT customer oriented in the slightest!
 
Fishunt
Its true on all of these Pentair variable speed pumps that the pump on low speeds runs with only a half filled strainer. As was claimed by Site Admin in this post, it may be an accumulation of micro air bubble and the low turbularnce in the basket not pushing the air out of the system. While I do think that is a portion of the problem, in my case I also am convinced the cover is leaking air into the system as well.

If your cover seal works, one thing I would suggest which I do is ramp up the pump for maybe 5 or 10 minutes at the end of your low speed cycle. The reason I do it is that I run 4 low speed cycles during the daylight hours - maybe an hour each in duration. This is in order to maintain a trickle waterflow through the chlorinator to keep chlorine going into the pool. This is a huge advantage of the slow speed approach. The disadvantage is that at slow speed the chlorine really does not distribute thoughout the entire pool, so I kick up to high speed for 5 or 10 minutes to better mix up the pool water which chlorine. This has the advantage of getting rid of any air in the filter and piping system. So if I could only keep the cover from sucking air..it would work great.
 
There's something wrong with your seal, cover or possibly even the wet end body. You absolutely should. It see air entering the cover or have water spurting out.

Try taking the cover off and cleaning it and the seal and the mating surface on the pump and then put. Liberal amount of pool lube on the o-ring. Then clamp it down tight. If it still leaks then the body may be warped and need replacing.

Low speed should not result in your pump half full of air - Jason was talking about a bubble at the top but not half the basket. You're seeing that because you have a serious air leak.
 
Do they all spurt water out of the top? Mine did once - when I didn't put it on tight enough. I run low speed (1150 rpm) for 10 hours a day in the summer and I don't get half my basket full of air. Air does accumulate but nothing more than the width of the top. I solve this by always running a 2 minute prime cycle at 2500rpm
 
If it is outgassing, it should take many hours before the pump gets to half level. Some have reported half full pump baskets only after 24 hours. I sometimes get a baseball size bubble after about 6 hours on low speed.

But it is difficult to know for sure if it is only outgassing or a combination with a small leak. On low speed, the pump lid will not seal as well because the suction is less so that can contribute some to the air.

As for squirting out water when the pump is shut off, many pumps exhibit this behavior and is not necessarily a sign of a poor pump lid seal. Again, pump lids are designed to seal under negative pressure and do not seal well when the pump is shut off and the pressure wave hits the pump basket.
 
Mark, he says he can see air entering the basket from under the cover. He's either not clamping it down tightly enough or his o-ring is bad or the body is warped which is the least likely. I'm inboard with the dissolved air etc on low speed but he's got bigger problems than just that.
 
Maybe the body is warped - the seal looks good - but you can only turn the lid 1/4 turn between off and tight and I just dont think that there is enough O ring compression in the full tight position.

After a full basket prime, if I drop to 1800 rpm I loose half the water in the basket in half an hour.
 

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