Single Speed vs Variable Speed, Pump Curves

rrdubya

Member
May 30, 2021
5
Tennessee
I'm a new pool owner or will be. I'm still trying to understand variable speed pump savings and whether I should go single speed or variable speed. I'm looking at the Hayward 1.65 hp Super Pump VS. I took a shot at calculating my TDH. I estimated it to be around 30. In looking at the pump curve for the Super Pump VS, it looks to me at a TDH of 30, I wouldn't have any flow until the pump was running at around 2400 RPM's. Am I reading that right? I like the idea of running the VS pump longer and slower but I'm not seeing where I could run it very slow. If I'm wrong in my TDH calculation and it was closer to 40, I'd need to run the pump at 2700 RPM to get any flow, the way I'm reading it. Am I reading this wrong. The hydraulics of this is confusing.
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
8,541
Southern OK
Pool Size
15000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
CircuPool SJ-40
This always makes my head hurt so I will let you read it..

A VS pump is almost always better unless you are trying to feed waterfalls or other high volume things... It can be run low rpm and have very low pressure on your system and that is a great thing :)

 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
43,662
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Do remember, starting July 19 of this year, a single speed motor/pump of 1.1THP and greater will NOT be allowed to be sold for primary pool pumps.
 

rrdubya

Member
May 30, 2021
5
Tennessee
It's starting to come to me now. The part I wasn't understanding was that as your GPM's decrease, your TDH also decreases. The pump curves make more sense now.
 

DeanP66

Well-known member
Mar 26, 2014
1,230
San Jose, CA
You can always install a flow meter like a Flo vis and that will tell you the different GPMs at the different rpms of your VS pump. They work quite well.
 
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