Pentair Intelliflo Variable Flow pump reporting incorrect GPM?

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B

beels

Well-known member
Jul 11, 2011
45
Plano, TX
My variable flow pump seems to be incorrectly reporting the flowrate in ScreenLogic after a few minutes of operation.

When I first start the pump, it shows a normal ~450-500 watts, 35 GPM and the spa fountain and tanning ledge returns are bubbling normally. However, after a few minutes, the power usage/wattage slowly decays to around 140 watts and the observed flow rate drops off substantially - as observed by those 2 returns barely functioning. The flowrate still shows 35 GPM on ScreenLogic, but the wattage has dropped to a mere 140-ish and the pump motor is very quiet, just barely running.

When I manually increase the flow rate to say 50 gpm, the power usage and observed flow rate (at the 2 returns) increase to about what the 35 gpm flow rate used to look like. As it continues to run a few minutes, the observed flow rate and power usage will start to increase. So I manually back the GPM down about 5 GPM, let it run a few minutes, back it down another 5 GPM, let it run a few minutes. Now I'm back at 40 GPM and power usage and observed water flow seem as expected for 35 GPM and hold constant.

If I back down another 5 GPM to 35 GPM, the power usage again starts to decay to the 140 range, and pump motor runs very slowly as per above.

The workaround I guess is to just run it at 40 GPM and let "40 be the new 35", but isn't this odd behavior?

The only thought I've been able to come up with is that perhaps my pump impeller might have some debris in it, thereby cutting the pump efficiency and observed flowrate.
 
B,

I am not a fan of running in the GPM mode, ever.. :mrgreen:

When was the last time you cleaned your filter?

If the actually flow at the pool returns decreased, my bet would be a dirty filter.

Thanks,

Jim R.
 
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The VF uses an iterative method to hunt for the set flow rate so it may take some time for it to zero in on the correct flow rate. I think you may be assuming the initial RPM/Wattage is the correct one while the final RPM/Wattage may actually be the correct one.

One additional check would be to go into RPM mode, set the RPM and then see if the wattage and/or GPM change with time.
 
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I would forget gpm modes and run on RPM's. GPM means nothing for pool operation. Only thing that matters is that your equipment (skimmers, heaters, SWG, and or features) work.
Your VS pool motor is to be used to save you money, by running slow, and and keep you pool sanitized via chlorine all the while saving you money. I would forget about the GPM mode as it not relavent to pool operation
 
Thanks for the response, Jim.

In this case, the observed flowrate at the returns was reduced because the pump motor was barely running, ~140 watts instead of 475-500. Also, I did a complete filter service only 2 months ago.

As this is a variable flow pump, I'm not aware of an option to run it in a different mode, such as, I guess, an RPM mode.

After I posted the above, I tried reducing the GPM by 1-2 GPM at a time, waiting a couple of minutes between each adjustment, and now the flowrate setting is back to 35, wattage is holding at 480-500, RPM at 1920-ish, both as expected, and observed flowrate is totally normal.

It seems strange how earlier, at the same 35 GPM setting, the pump output and power consumption dropped off so radically. I want to inspect the impeller for debris buildup, but I don't wat to break the seal.
 
I have had this VF pump for a long time and am very familiar with specs it reports at various settings. In my setup, at a 35 GPM setting, the power consumption is always around 490-ish with a clean filter. As the filter gets dirty, the consumption will increase to maintain the flowrate.

Something it not quite right that it starts up at the normal power level and observed flow, then drops off to a miniscule 140 watts and tiny flowrate while being set at 35 GPM, but then if I start high and gradually drop back to 35 everything is as expected.
 

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