How to read pump curves

[JayG]

I know this has been covered, but this question still perplexes me. I'm looking at a variable flow pump for next season and I came across this graph for the Pentair Intelliflow:

View attachment 42644

What can I learn from this graph? Thanks in advance.

Jay

 

[Agent99]

Cool. You found one with a lot more lines and given in Watts. I've only seen the one on Pentair's site and it has 4 pump curves representing the factory preset speeds. I sort of had to guesstimate where I felt my system fell. Is that for the 011018?

I found this PDF from Hayward helpful: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB8QFjAAahUKEwjGlpHG0e_HAhVQQZIKHcoxA9c&url=http%3A%2F%2Fwww.nuccibros.com%2Fsec_0934drRb_dl%2Fdata_sheets%2FHydraulics%2520%2520and%2520Pump%2520Sizing%2520for%2520Existing%2520Pools%2520Guide.pdf&usg=AFQjCNERmQ16Sz6W-Sqg4GI8zBGGkjV0_w&sig2=_T3RDu3v_aj1GqBplCePGw

 

[JayG]

Cool. You found one with a lot more lines and given in Watts. I've only seen the one on Pentair's site and it has 4 pump curves representing the factory preset speeds. I sort of had to guesstimate where I felt my system fell. Is that for the 011018?

I found this PDF from Hayward helpful: https://www.google.com/url?sa=t&rct...Sqg4GI8zBGGkjV0_w&sig2=_T3RDu3v_aj1GqBplCePGw

011012 is the number I saw. 3 hp intelliflow.

Interesting read, BTW. Thanks.

 

[Agent99]

Also, read the very first thread in this forum.

 

[mas985]

In order to gleam any information off the curve, you would need to know your plumbing curve. If you were to plot your pluming curve over that chart, you could then determine the energy use for different flow rates (RPM). But there is also a spreadsheet for that (see my sig).

 

[JayG]

In order to gleam any information off the curve, you would need to know your plumbing curve. If you were to plot your pluming curve over that chart, you could then determine the energy use for different flow rates (RPM). But there is also a spreadsheet for that (see my sig).

Thanks! Right now I have a single-speed (3450 rpm) Superpump II (1.5 hp). I have no idea what flow it produces. I purchased the Jandy check-valve flow meter from TFT. I will try to install it this weekend. Once I know the flow that pump produces in my pool, what next? I opened your Intelliflo spreadsheet in Google but it says it is "read only". I cannot change any of the values. The Excel spreadsheet works fine, but I'm not sure what I would input from my existing system: rpm? gpm? I won't know the watts. Sorry if I'm a bit clueless on this, but I'm simply trying to figure out how a VS pump will perform in my pool. We pay $0.23/kWh here in Westchester county and I'm trying to figure out if it makes sense to buy a larger pump that can loaf along at 35 gpm and occasionally run at higher flows for skimming or whether I should get a lower HP pump like the Tristar (1.65 hp) that would work closer to its full rating more of the time. Or a simple 2-speed pump that either runs high or low.

I'll read through your Hydraulics primer again. Maybe eventually it will sink in.

Thanks for all your efforts to help the hydrodynamically-challenged.

Jay

 

[mas985]

I opened your Intelliflo spreadsheet in Google but it says it is "read only"

You have to make your own local copy so you can make changes. File -> Make a Copy

However, this spreadsheet is for those that already have an Intelliflo. It won't do you any good if you don't know your RPM and wattage (both are displayed on the Intelliflo panel).

but I'm simply trying to figure out how a VS pump will perform in my pool.

If it is economics of the pump you are interested in then use the "Energy Cost" tab in the Excel Pump Tools spreadsheet. It is pretty much set up and you just need to replace the costs with current costs and your electrical rate.

 

[JayG]

Thank you. That "Energy Cost" tab is very helpful. It looks like I could be saving ~$190/month in electrical costs over my single-speed pump. Amazing.

 

[JayG]

I installed the TFT flow meter into the Jandy check valve in my pool pad. The flow reads ~61-62 gpm with my 1.5 hp superpump II at 3450 rpm. That seems to put me squarely in "curve A" territory if I'm interpreting this correctly. The only caveat is that the filter PSI is reading 18 whereas it was ~12.5 psi when I remember checking it a few weeks ago. So maybe the filter needs to be cleaned. I assume this might impact flow, but so far it seems my intuition about how pumps work has been flawed. Does any of this information help me choose a new VS or 2-speed pump for next season?

 

[Agent99]

Filter might need cleaned although I'd suspect the sub-par pressure gauge might be either clogged with something or simply malfunctioning itself. Flick the gauge with your finger a few times. Does it at least go to zero when everything is off? I have the same cartridge filter and they tend to go a fair amount of time between cleanings (one reason I like them) unless you've gone through an algae clean up recently or something.

I have the same flow valve...pretty darn cool, eh? Now you have a bit more data to use. However, you have the bare minimum in pool equipment so there's no doubt in my mind that at least a 2-speed would do you some good and save you some electricity.