Efficiency of Intelliflo VSF and other questions

lakeboater

Bronze Supporter
Mar 8, 2018
32
Naples, FL
I recently replaced an aging Sta-rite 1 HP pump with an Intelliflo VSF. The VSF reports total head, electrical power usage and flow along with rpm and allows for a complete picture of system performance. It gives me an excuse to make an Excel spreadsheet for something other than honey-dos and Christmas gifts. I digress.

I took the opportunity to re-plumb to upsize the short 1.5" inlet with 2.5" els and 2" pipe. I also lengthened the suction inlet to 12". I was able to upsize the outlet and reduce bends. The only disappointment was leaving a 1" length of 1.5" pipe inside the suction side Jandy diverter valve.

It was interesting to qualify the energy saving benefits of the VS pump. The flow data makes it easy to select the ideal heat pump flow. I did end up with a few questions and hope that @mas985 or other pump experts would provide their thoughts on these questions:

1. With the large suction side plenum (and inlet basket labyrinth), is the recommended 5 X diameter straight section really helpful for impeller function?

2. I calculated efficiency (hydraulic power/electrical power) of .46 to .47 in the 2250 to 3000 rpm range for the VSF. The head at 50 gpm is 44 ft. Is that efficiency level expected for this pump?

3. What efficiency would you expect for the old Sta-Rite (PHK2RA6E-102L)?

4. What is the proper efficiency term for what I calculated? It seems like a combination of pump efficiency and motor efficiency.

I will appreciate any thoughts.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,733
Pleasanton, CA
1. With the large suction side plenum (and inlet basket labyrinth), is the recommended 5 X diameter straight section really helpful for impeller function?
No. The pump basket evens out most of the impact due to a close in fitting.

2. I calculated efficiency (hydraulic power/electrical power) of .46 to .47 in the 2250 to 3000 rpm range for the VSF. The head at 50 gpm is 44 ft. Is that efficiency level expected for this pump?
For higher head loss plumbing, that is about right. For lower head loss plumbing, the efficiency would be above 50%.

3. What efficiency would you expect for the old Sta-Rite (PHK2RA6E-102L)?
~37% for Curve-C

4. What is the proper efficiency term for what I calculated? It seems like a combination of pump efficiency and motor efficiency.
It is sometimes called wire to water efficiency.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
19,212
Bedford, TX
LB,

You must either be an engineer or just have way too much free time... :mrgreen:

I know absolutely squat about all the calculations you guys are doing, or pump "wire to water efficiency." The only thing I know is that I can run my IntelliFlo 24/7 for less than $20 a month... Any gain by fussing with it, is not worth my time..

You have a great pump.. Relax and enjoy it. :poke:

Thanks,

Jim R.