Got my new Intellifo VSF installed today, but flow doesn’t seem right

etuser

Well-known member
Mar 28, 2020
130
Houston
Hi - So after being down for 10 days, finally got my Intelliflo VSF installed today. I know most on here shy away from the "F" portion of the pump, but I do have a question related to that. Running it at 3000 rpms, it says I am using 1300 watts of power and it is flowing at 40 GPM. Those numbers seem odd to me - would have thought 3000 rpm would have been more wattage usage and more GPM. Does that make sense to others?
 
Last edited:

scottts

Gold Supporter
Nov 13, 2019
151
Gilbert, AZ
I have a VSF pump as well. Right now its running in constant flow mode - 40 GPM, 1936 RPM and 450 watts. My power usage and RPM to get 40GPM jump around as I have in-floor cleaning and the number of heads varies per position so the pump is always revving up and down slowly to maintain the 40 GPM.

The amount of power and RPM to get a certain flow will depend on many things that affect the "resistance to flow". Like how clean is your filter for a big one.
 

JamesW

TFP Expert
Mar 2, 2011
20,724
40 gpm is way low for that speed. It indicates a restriction on the suction or return or both. What is the filter pressure?
 

etuser

Well-known member
Mar 28, 2020
130
Houston
Pressure gauge reading 25. DE grids were removed and cleaned a month ago. The pool has sat idled the the past 10 days and the looking glass is green.
 

JamesW

TFP Expert
Mar 2, 2011
20,724
I would open the de filter and give it a good cleaning.

I would limit the pump speed to about 2400 unless you really need that much flow.

I would check the vacuum reading with a vacuum gauge in the front drain plug hole, but don't overtighten the gauge as it can crack the drain hole.

Check the skimmer baskets to make sure that they're clean.

Do a heater bypass if you need more than about 60 gpm of flow.

The heater creates a lot of restriction.
 

etuser

Well-known member
Mar 28, 2020
130
Houston
Thanks James. I backwashes the filter briefly and pressure went down to 18 and flow went up to 50. I suspect the filter needs to be cleaned again. I have dropped speed down to 1200.
 

Flying Tivo

Well-known member
Jan 24, 2017
1,889
Monterrey, NL, Mexico
During the 10 days of downtime, did you feed it chlorine? The sightglass comment makes me thing you have algae. You will need to slam.
Can you post test results? I also have a VSF and have not exceded 26gpm ever. I usually run around 1200rpms thats about 15gpm in my system, thats around 90 watts.
 

etuser

Well-known member
Mar 28, 2020
130
Houston
Thx. Yes, fed it chlorine and used sheer pump to keep the water circulating a bit. I am worried I have algae in the filter, but will need to test and go from there. Thank you.
 

etuser

Well-known member
Mar 28, 2020
130
Houston
So I opened the filter and rinsed off the grids. They looked pretty clean. I can pickup a pressure gauge. I looked on HD and Lowes website, but didn't see that they sell one in the store. Anyone know if they carry them in store? If not, any recommendation on which one to grab from Amazon?

I can't bypass the heater. Skimmers and pump basket are clean.

At 1200 rpms, SL shows "--" in the flow section.

Also, called Pentair - the man I spoke with seemed to think it could be an issue with the reading from the pump or in ScreenLogic as opposed to any actual flow issue, but not sure.

At 1200 rpms, SL shows "--" in the flow section.
 

JamesW

TFP Expert
Mar 2, 2011
20,724
Put the system in service mode and operate the pump from the pump controller.

Try different speeds and note

1) Speed rpm.
2) Flow gpm.
3) System pressure (from the pump control panel).
4) Filter pressure.
5) Watts
6) Vacuum pressure if you have a vacuum gauge in the pump front drain plug hole.

 

etuser

Well-known member
Mar 28, 2020
130
Houston
James -

1200 rpm, 8/9 gpm, 4psi (pump), 3 psi (filter), 87w
1500 rpm, 14 gpm, 7 psi, 6 psi, 165w
2350 rpm, 32 gpm, 18 psi, 14 psi, 665w
3100 rpm, 46 gpm, 31 psi, 23 psi, 1507w

I don't have a vacuum gauge, but if someone can point me in the right direction on where to get one locally, amazon, or elsewhere, I can pick one up.

Thanks.
 

JamesW

TFP Expert
Mar 2, 2011
20,724
Maybe a restriction on the suction side.

Google vacuum gauge 1/4 npt.

It can screw into the front drain plug of the pump and tell you the vacuum reading.

Don't overtighten the gauge as it can crack the drain plug hole.
 

JamesW

TFP Expert
Mar 2, 2011
20,724
Hard to tell. The numbers seem a little bit off. I'm not sure how much I trust the flow measurement that's being done by the pump anyway. The gpm is calculated from speed and power usage, which I think can be unreliable.

A flow meter would be helpful to see how accurate the pump measurement is.


F30200P (2" pipe horizontal pipe).

A vacuum gauge would also be helpful.
 

JamesW

TFP Expert
Mar 2, 2011
20,724
The system pressure from the pump is the total pressure (suction + return).

If the total is 31 psi and the return is 23, that leaves 8 psi for the suction.

8 psi is about 18.5 feet of head (8 x 2.31), which is way too high for 23 gpm going through 2" pvc pipe (46 gpm through (2) 2" pipes).

Maybe both skimmers are clogged or maybe there's a clog in one of the valves in front of the pump.

I would open the valves and check for any clogs.

I would also install a flow meter (after the filter so that the water is clean. Dirty water will clog the flow meter).

I would install the vacuum gauge to see if it's actually 8 psi.

Note: Vacuum gauges are not usually in psi, so you have to convert the units to psi or feet of head.
 

etuser

Well-known member
Mar 28, 2020
130
Houston
Ok thanks. For starters, I will open both valves tomorrow and see if I can find anything.

Another thought - I will put it in spa mode tomorrow and check the results.
 

etuser

Well-known member
Mar 28, 2020
130
Houston
Ok, so I just went and checked both valves. Both looked clean as a whistle. I also put it in spa mode and noted that at 2350 rpm, it is showing 27 gpm and 626watts as compared to 32 gpm and 665watts in pool mode. Does that mean it probably isn’t a suction side issue?
 

JamesW

TFP Expert
Mar 2, 2011
20,724
The flow seems lower than I would expect.

I would get the flow meter and vacuum gauge to see if the pump numbers are accurate.

Do you have a picture of the system as it looks now with the new pump?
 

JamesW

TFP Expert
Mar 2, 2011
20,724
The heater creates a lot of restriction above about 60 gpm. So, that should be ok.

The tab feeder creates excessive restriction.

Is the return just a single 1.5" pvc pipe?

What is the pump part number (P/N) from the front sticker with the barcode?