Intelliflo VS -- flow, head, power

[smallpool]

I've been playing with the RPM of my Intelliflo with the spreadsheet that Mark's produced and cross referenced with Pentair's chart. I found some anomalies; would they make sense? Note that I'm putting ranges, as I see the watts very over time.

RPM Watt GPM (Mark's chart) TDH (Penair's chart)
1100 145-155 19-25 10/9
1400 185 11
1500 228 17 19
1600 286 26
1800 409 37
2350 845 52 40
2400 891 53

Questions:
- Does it make sense that 1100 RPM has 2x the flow than that at 1400?
- There are huge jumps in power between 1600 & 1800 RPM (1.5x) and 1800 and 2350 (2x). Is that due to the head increase with flow increase?

 

[mas985]

Which spreadsheet are you using? The one that has watts as an input will only work if it is calibrated at near full speed and then the estimate used for lower speeds. It is not accurate when inputting the wattage for low RPM. The reason is that the power curve is very flat on lower speeds so any error is reflected as a huge GPM error. The spreadsheet should have a warning about this anomaly.

 

[chem geek]

See my old post where I listed GPM, RPM and Watts with my Pentair Intelliflo with the solar turned off. From 1185 to 1460 RPM there is a jump in wattage from 155 to 255 Watts so 1.65x in power and from 15 to 24 GPM so 1.6x in flow so that's less than you see in the table. From 1495 to 1805 RPM there is a jump in wattage from 275 to 420 Watts so 1.5x while from 1805 to 2310 RPM there is a jump in wattage from 420 to 835 Watts so 2.0x so these are consistent with your numbers.

Yes, the huge jumps in power are due to the head increase with the flow increase. As noted in Hydraulics 101 - Have you lost your head?, the pump affinity equations show that the power varies as the cube of the flow rate whereas the RPM and GPM are more linearly related. These aren't exact relationships because for power there is energy usage even when there is no flow rate (energy usage in the resistance of the windings and in powering the electronics for the pump) and there are less than ideal losses at the lower flow rates requiring more RPM than expected at the low GPM.