Variable speed pump and TDH

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W

Werdnaycart

0
Aug 19, 2018
64
Lutz, Florida
Hello, I'm looking at possibly replacing my old Hayward 1HP pump with a new Purline 1.65 VSP PL2605. (main goal would be to save energy) I've calculated my TDH to be around 60 using a vacuum and pressure gauge on the pool pump. When I look at the literature for the PL2605 it doesn't have any flow rates for a TDH of 60 until you get up to 85% output. Does this mean this pump wouldn't work for me at any settings less than that?
pureline-prime-165-vsp-pump-curve.jpg


Here's how I came up with my 60 TDH

I had a 13.5"Hg on suction, and 19PSI on the pressure gauge. 13.5"Hg*1.13= 15.225....19psi*2.31=43.89...15.225+43.89=59.145. I rounded 59.145 to 60 for easy reference. Does this seem correct?


Thanks for all the help!
 
What you measured is at your single speed pumps full rate. When you run the VS pump, it will run at a lower rate and thus a lower TDH.
 
Typically when you can run at a lower speed, the electrical usage is less even in a larger pump. There is a lower limit on speed, normally between 1000 and 1200 rpm as the pump gets less efficient at speeds lower than that.

You can easily go with the larger VS pump. With a sand filter no heater you should have no issue with it.
 
mknauss said:
Typically when you can run at a lower speed, the electrical usage is less even in a larger pump. There is a lower limit on speed, normally between 1000 and 1200 rpm as the pump gets less efficient at speeds lower than that.

You can easily go with the larger VS pump. With a sand filter no heater you should have no issue with it.
Click to expand...



Ok, I think I'm getting lost in the weeds with the math. Looking at the plumbing curve for my current pump (model is SP2607X10) I show that if I have 60 TDH, my GPM is about 30 GPM. If I were to get a larger pump and was attempting to get a flow rate of 40GPM, would my new TDH be 106? New Head = Current Head (Target GPM/Current GPM)^2

hayward-super-pump-curve.jpg


That's off the charts of performance data below...is there a way to calculate the flow rate of the pump below given what I know (TDH and Flow Rate) of my current pump?

Are my numbers normal? This was an inherited pool with 1 1/2" plumbing...

pl2606-pump-curve.jpg


Thanks again. I've read the Hydraulics 101 thread a few times, and I think some of it sunk in...
 
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