Hayward Waterfall Pump dead, can I replace with Whisperflo?

troye

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It was a good run! I have had the Hayward Northstar Pump for almost 20 years. I did replace the motor about 5 years ago. It was making a loud whine for the past two months so I knew it was on the way out.
It is a 1.5HP, with service factor of 1.25, with total HP of 1.88.

The pump is used for a waterfall and I was thinking to replace it with a Whisperflo 2.0 or 3.0HP. There is a small company who rebuilds the whisperflo pumps and completely reconditions for $420 OTD for the 2.0HP

I have a 1.5HP Whisperflo used for a slide / waterfall that is 100' from the pool pump and it does the job just fine (second pic). Slide/Waterfall is on the far left.
The waterfall is approx 40' from the pump and is about 10' above the waterline. Waterfall pump sits just to the left of the slide/waterfall

Both the slide/waterfall and the waterfall are the same height. Plumbing is 2 inch.

I assume the Whisperflo 2.0HP will work? Or should I just replace the motor again and call it a day? It will be very challenging to get the Hayward back in as it is very tight sitting under a fake rock with a small wall infront. I had to remove the motor lock ring before removing the pump. Reinstalling is probably do-able but a serious, serious, serious PITA. I might have to buy the dual speed California title 20 compliant motor. It is service factor of 1.3 so I assume it is about the same as the existing.

There is a small local company who rebuilds the whisperflo pumps and completely reconditions for $420 OTD for the 2.0HP (single speed)
The motor replacement for the Hayward will be around $350

Maybe there is another option I should consider like perhaps an actual waterfall pump lol, Hayward TriStar maybe?

Thank you very much.
 

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ajw22

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If it will be challenging getting the Hayward back in wouldn't it be equally challenging getting any replacement pump into the same spot? And if you get a different pump you need to conform it will fit into that space.

You are in California??? Please put your location in your profile so it shows up...
<----here

If you are in CA then your pump choices are further limited.

Given your limitations I would just replace the Hayward motor if you can.
 

troye

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The Northstar has the motor lock ring with the handle which is what makes it so tight to get in/out, but there is plenty of space where the pump sits.

I can get a Hayward Tristar 2.0HP locally 6 months old. Or the replacement motor for the Northstar, or a fully reconditioned single speed Whisperflo.

My phone is down but I will try to get a pic to show what I am dealing with.

Profile Updated ;)
 
Last edited:

ajw22

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I can get a Hayward Tristar 2.0HP locally 6 months old. Or the replacement motor for the Northstar, or a fully reconditioned single speed Whisperflo.

@mas985 which pump is preferred for a low head waterfall?
 

mas985

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Waterfall pumps are a good choice IF the plumbing is actually low head. What size is the plumbing for the waterfall? I assume both the suction and return lines are dedicated for the waterfall? How wide is the waterfall?

As for a choice, almost any waterfall pump will do if it has the correct flow rate and head. That depends on the above questions.
 

troye

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Yes both suction and return lines are dedicated - 2"

Top Basin is a little shy of 4'. Widest point of Waterfall is 8'
 

JamesW

TFP Expert
Mar 2, 2011
27,703
The AFP models have a strainer.

If we model your system as 200 feet of 2” pipe, we get about the below curve.

The water velocity should not exceed 6 feet per second on the suction side.

You might be able to get up to 100 gpm without cavitating, but that is a risk.

The AFP-75 will give you about 65 gpm.

The AFP-120 will give you about 76 gpm.

The AFP-150 will give you about 82 gpm.
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troye

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From pool to Pump to waterfall the distance is 50' max.

Any idea what a Hayward Northstar 1.5HP is GPM?
 

JamesW

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Mar 2, 2011
27,703
Here is the problem with a WhisperFlo on a low head loss system.

The system curve ends up at the far right of the curve, which is full runout, which will usually result in cavitation.

The only pumps that might work without exceeding the 100 gpm suggested maximum limit would be E (0.5 hp x 1.90 = 1.95 total hp) or F (0.75 x 1.67 = 1.25 total hp).

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mas985

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I get a plumbing curve of:

Head (ft) = 0.003 * GPM^2 + 10 (There is a 10' lift)

The Northstar was producing about 113 GPM on that plumbing curve. I don't believe a waterfall pump will work. A 1.5 full rated Whisperflo would deliver close to the same.
 

troye

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So, the suction is 25 feet and the return is 25 feet or are they 50 feet each?
From pool to Pump is 10'
Pump to Waterfall is 35'

Excuse my ignorance please, is there a return line for a waterfall? In any case the max would be 90-100'
 

troye

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I get a plumbing curve of:

Head (ft) = 0.003 * GPM^2 + 10 (There is a 10' lift)

The Northstar was producing about 113 GPM on that plumbing curve. I don't believe a waterfall pump will work. A 1.5 full rated Whisperflo would deliver close to the same.
Getting somewhere thank you both for your feedback. Any harm in going with a 2.0HP ? There is a Hayward Tristar pump single speed 2.0HP locally as well I believe that should also work?
 

JamesW

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Mar 2, 2011
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If it's 100 feet of 2" pipe and 10 feet of lift, I get y=0.0015x^2 + 10.

So, maybe 115 gpm on a SP4010NS

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troye

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What is the model number of the Northstar pump?
No idea! It is 20 years old and I cannot find the model # anywhere. It is paired with a 1.5HP Century motor. See my first post with a pic of the pump
 

JamesW

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Mar 2, 2011
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There is a pipe from the pool suction port to the pump and then a pipe from the pump to the waterfall.

What is the actual length of each pipe and how many 90s are on each line?
 

JamesW

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Mar 2, 2011
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You probably have a SP4010NS, which has a total of about 1.65 to 1.85 hp.

You might think that it's the SP4015NS, but that has a total hp of about 2.2 hp.

In any case, the suction is undersized and you risk cavitating the pump if you try to get too much flow.

Does the pump sound loud like it's pumping gravel when it runs?
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