Variable flow pump.... HOW THEY SO SMAHT???

CRUSH-IT!

Gold Supporter
Jul 29, 2017
43
orlando, fl
Pool Size
24000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Turbo Cell (T-CELL-5)
I can think of a number of ways to calculate flow for pump speed modulation.

1) pressure sensor on each side of the pump gives TDH and pump speed plotted against the pump curve gives flow.

2)Power consumption plotted against pump speed allows calculation of TDH and by extension Flow.

3) Each pump comes with a little genie that lives in the pump and sticks his toe in the water and adjusts pump speed accordingly.

4) something better than 1-3.

Anybody know?
 

JamesW

TFP Expert
Mar 2, 2011
22,092
Note that at a constant speed, increasing the TDH reduces the power needed because the flow is reduced, which reduces the power used.

So, the power is graphed against the flow and not the TDH.

The power does increase with higher TDH if the flow is maintained by increasing the pump speed.
 
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CRUSH-IT!

Gold Supporter
Jul 29, 2017
43
orlando, fl
Pool Size
24000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Turbo Cell (T-CELL-5)
Thanks again! Im a bit surprised how hard I have found it to find complete pump curves for these pumps. that is, curves for more speed or flow levels. I would think the manufacturer must provide them
 

CRUSH-IT!

Gold Supporter
Jul 29, 2017
43
orlando, fl
Pool Size
24000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Turbo Cell (T-CELL-5)
I understand that if pressure changes rapidly the pump will often downshift and upshift. I suspect this may be diagnostic. If you have power and speed and reduce speed to get a new power and speed in the same circuit configuration, you get a pair of simultaneous equations which can be solved to more accurately estimate flow and TDH. I suspect this gets them accurate enough for government work.
 

JamesW

TFP Expert
Mar 2, 2011
22,092
It would be helpful to have a software program that can determine the power, RPM, TDH and flow when given two of the variables.

I'm sure that they probably have it, but getting it might not be easy.

They have a new metric called WEF which is supposed to help identify the efficiency of pumps, but it is completely worthless.

Being able to calculate the power usage at a given GPM and TDH would be helpful to determine the efficiency of one pump vs. another.