IntelliFloXF VSF RPM vs GPM

[cactus_LV]

I was wondering if using GPM or RPM is better when setting different programs in the intellicenter. I assume GPM is better in theory since it adjusts based on filter resistance and other things but I wasn't sure if it's actually that smart/ good.
Also I noticed that the set GPM in the pump is not the same as what my FlowValves show. For example I set the pump GPM to 40 GPM and the pump shows it's running at 40 GPM but the FlowValve shows 55 GPM - is that just the inaccuracies in the system?

Another thing I noticed is that when I set the pump for example in the solar circuit to 40 GPM it sometimes runs at 50 GPM for whatever reason.

 

[Jimrahbe]

Cactus,

I am not a fan of GPM, because it just makes people go down the flow-inaccuracy rabbit hole...

In the old days everyone had a VS pump and all they cared about was making something work. You need the SWCG's flow switch to close.. just crank up the RPM until the flow switch closed. No one cared what the flow was as long as it worked.

Now we have people all concerned because the flow is different when measured by different devices and locations.

A good analogy is the volume on your TV. You don't look in a manual and set your volume to a specific number, you just adjust it up to the volume you like. Your volume may be very different than your neighbor's volume.

All pools are different.. just because the manual says a SWCG will turn on at 25 GPM, does not mean it won't turn on at a lower GPM, or that it might take more GPM to work.

I run my pool to enjoy it. For me anyway, worrying about the accuracy of a flow gauge, or GPM reading, is just a waste of my time.

I am sure others here at TFP will have opposing points of view...

Thanks,

Jim R.

 

[cactus_LV]

I want my solar system to run at 50GPM independent of how dirty/ clean the filter is so I thought setting it a certain GPM would make my life easier but it seems like I should just stick to RPM and call it a day

 

[Jimrahbe]

Cactus,

It is your pool and you should run it however you want...

That said, if your filter gets dirty enough to effect the operation of your solar system, then the problem is not GPM.

You have a CCP-520 filter... It would have to be really, really dirty before that would happen.

How often do you clean your filter?

I also have the CCP-520 and like to clean my cartridges twice a year.. I'm sure I could go a whole year, or more, between cleanings, but my OCD won't let me..

Thanks,

Jim R.

 

[Newdude]

You have a CCP-520 filter... It would have to be really, really dirty before that would happen

+1

I just cleaned my 500 sq ft filter, and it was nasty. The pleats were caked up to the point it was a smooth gray surface most of the way around. I forgot my baseline but figured with spring long over, it couldn't hurt. The baseline remained unchanged before and after even with how nasty they were. 18.5 is now sharpied on my garage wall so I remember next time.

 

[cactus_LV]

I guess I’m cleaning it too much then 3 times a year I haven’t had solar long enough to actually get the filter dirty.

 

[Jimrahbe]

Cactus,

The real reason that I do twice a year, is because when I clean the cartridges I get wet!!! I don't want to have to clean the filter in the middle of the winter and the middle of the summer is just too hot for me. So, cleaning in the Spring and in the Fall, when it is hot enough to get wet, is what works for me best.

My filter pressure never moves enough to justify cleaning based on filter pressure, so I just more or less do it on a routine schedule.

Thanks,

Jim R.

 

[cactus_LV]

I am still curious to understand why there is such a big difference between the pump GPM and the FlowValve reading

 

[matthewsunshineflorida]

I am still curious to understand whey there is such a big difference between the pump GPM and the FlowValve reading

I think it's because the intelliflo is just measuring resistance at a given RPM and estimating GPM from that using the published pump curve - without knowing the actual feet of head in YOUR system. Because of this, my observation is that the intelliflo reported GPM is relatively, but not absolutely accurate. Meaning if it is set to 36 GPM, I get around 45 GPM regardless of increased pressures from heater/solar. Solar manufacturers seem to recommend around 1-1.4 GPM for every 10sqft, so my 500sqft Helicol array recommends 50-70 GPM. Given that, I find it more helpful to set based on GPM.

I also believe the reason solar has that range is for efficiency during the highest BTU time of the day (direct sun in the summer), because heating efficiency is improved by increasing the flow and reducing the temperature differential between the source and heated water. This is because you lose heat through the pipe and atmosphere during transfer, and also because the closer you get to the maximum temperature of the heating source, the slower it will heat (like an asymptote).

In other words, to maximize both savings and heating efficiency, you'd probably set solar to a lower GPM and then have your pump kick on higher during the hottest part of the day. The goal would be to keep the temperature coming out of your returns only a few degrees warmer than the pool. I did some tests while writing a variable speed solar controller in python, but I only went through the trouble because my intellicenter's solar controller got fried during Hurricane Ian.