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Pump Configuration and Power Question

Posted by back_yard_lap_pool (My Page) on
Fri, Sep 28, 12 at 17:59

Future pool construction - 72K gallon pool.

Question on pump configuration:

Initially I was going to plumb the pool with a single IntelliFlo VF coupled with a Pentair Clean and Clear 520SF cartridge filter.
I could then run the pump at low speed (72gpm) 24/7, flipping the pool almost 1.5 times a day. If needed, I could crank it up to full power and flip it almost 3 times in a day to combat algae bloom.
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I had another thought recently though. I could plumb the skimmers (3 to 5 of them) to a 1/2 or 3/4 HP Whisperflo pump and run that 24/7, and plumb an Intelliflow VF to the main drains, cycling it for an hour or two per day to help stir things up.

IE:
Circuit #1
Skimmers - Whisperflo 1/2HP pump - Clean and Clear Filter - (2) IC40 chlorinators - acid dispenser - returns (Run 24/7 @ 60-70 gpm) (75 cents a day)

Circuit #2
Main Drains - IntelliFlo 3HP pump - 2nd Clean and Clear Filter - 400K BTU heater - run 1 or 2 times a day to help agitate the water with separate returns to pool than the 1/2 HP side of system

What I hope to gain:

1) More efficiency from a Whisperflo pump that is designed specifically to operate at one power setting (Blades engineered to run optimally @ 1/2 or 3/4 HP rather than all speeds)

2) Saves the more expensive IntelliFlo pump from wear and tear - Use primarily to run sheer descents & other pool features that need varying volumes of water, helps cycle pool quickly if needed to combat algae, etc. Can use to draw cold water from bottom of pool in winter, heat it and cycle it back into the pool.

3) Up to 3.5HP (200+GPM) at the ready to blast the pool if needed

Any thoughts?

Thanks!


Follow-Up Postings:

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RE: Pump Configuration and Power Question

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RE: Pump Configuration and Power Question

So where do you live where energy is only $0.026/kwh.

A Whisperflo 1/2 HP pump (WFE2) will use around 1200 watts which is 29 kwh/day. At $0.10/kwh that is $2.90/day or $87/month.

Seems like a waste of energy to me. The Intelliflo should be able to handle all that with much less energy use.

#1 is incorrect. The Intelliflo is more efficient than any single speed pump for the same flow rate.

#2 Most of the Intelliflo failures are the drive and that is usually due to lightning and not run time. Surge protection is probably you best defense against pre-mature failure.


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RE: Pump Configuration and Power Question

Ditto to Mas.

Depends on where you live, temps, how much it will get used ect.
I would run two filters and two VS pumps with IC-60's on each. You dont want to put them both on the same as you will have to run them in parallel, and they wont work on low speeds. Two IC-40's will be pushing them hard to keep up.

That way you can run them both on low speed 24 hours a day and save a ton on electric, pay for the difference in no time. Second one can double as waterfall pump.
These pumps are perfectly happy running slow speeds long times. They don't get hot, which is what kills the motors.
As Mas said, the only premature failure has been with some kind of electrical issue frying the drive.
Also you will want to make provisions for a second heater on the second pump, one 400k will have tough time with that much surface area.


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RE: Pump Configuration and Power Question

@mas985: I misjudged power consumption on 1/2 HP pump (dramatically) I figured 746 watts/HP, so 1/2 HP = 373 watts but did not figure in any wasted wattage. 1,200 watts means the pump operates at around 30% efficiency. Is this the case with all pool pumps?

We pay a little over 8 cents a KWH in west Houston.

On #1, I figured since the blades could not vary their pitch, a single blade design could not be efficient across all rpm's from 500 rpm through 4,000 rpm.

On #2 - we have a whole house surge protector at the top of our main load center. Is this what you are referring to, or is it a surge protector closer to the pump location?

@ just-a-pb
I was leaning towards the VF pumps based on some of the forum threads I had read in the past. Is the VS the way to go now in the Intelliflo product?

I was up in the air on the IC-40 / IC-60 decision. - Living in Houston (hot, sunny and humid) - I agree I should probably put a little more chlorinator horse power in the system.

How much wattage would you say an Intelliflo VF/VS would draw pumping 36 gpm with 35' of dynamic head pressure? Is there a calculator for this?

I had the same thought on the heater - pre-plumb a pipe large enough to supply both heaters. I am going to try using a "T-star" thermal pool cover on the pool with the single 400K BTU heater to see how expensive it is to keep the pool @ 74 degrees during the winter months. The coldest month average temperature we have in Houston is around 51 degrees so hopefully it won't be too terribly expensive. I'm hoping less than $300/month in natural gas. Otherwise, we may squeeze into the triathlon wet-suits to train during the winter time. Firing up (2) 400K BTU heaters would cost quite a pretty penny I bet...

Thanks both just-a-pb and mas985 for your advice. Back to the drawing board for me. LOL!

J


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RE: Pump Configuration and Power Question

First, a 1/2 HP pump is actually not a 1/2 HP pump. Label HP means very little. The WFE has a service factor of 1.9 so technically, the total HP (THP = HP * Service factor) for the WFE is 0.8 HP. So the efficiency of the motor is around 49.7% although the published efficiency is 68.7%. Larger motors tend to have better power efficiency but they cost more to run.

Also regarding #1, there are no blades in a pump only the impeller and it has vanes. Plus there is no difference in a VS wet end vs a single speed wet end. In fact, the Intelliflo series use the same wet end as the WFE 12. Flow rate is changed by changing the rotational speed of the motor using a variable frequency drive (VFD). In a two speed pump, the speed of the motor is changed by switching to a different set of winding's.

Next having 35' of at 36 GPM would be extremely high head loss for that GPM and would be the equivalent of a pool with 1.25" or smaller plumbing. I am not sure where you got the 35' of head from but a typical pool with 2" plumbing should have head loss less than 11' @ 36 GPM. Don't forget that head loss is proportional to GPM^2.

But to answer your question in a different way, the Intelliflo @ 1100 RPM on the CEC plumbing curve-C would draw about 150 watts and have a flow rate of around 33 GPM. This would be the most efficient setting.

When comparing pumps it is best to use energy factors (gallons/watt-hr). Again using the CEC plumbing curve-C as a reference, the energy factor the VS at full speed (97 GPM @ 2720 watts) is 2.14 while the WFE (68 GPM @ 1200 watts) 3.4. The Intelliflo at the same flow rate as the WFE 2 (68 GPM) would draw about 860 watts for an energy factor of 4.74 so clearly better than the WFE 2. Even better though the Intelliflo at 1100 RPM has an energy factor of 13.2 which would be very inexpensive to run.

A 72k pool is very large but a single Intelliflo with the right plumbing could turn it over in 12 hours which should be plenty. At 1100 RPM, you would turn over 2/3 of the pool in 24 hours but that may be enough. I find I only need about a 1/2 turn per day to keep the pool clean.

I would save yourself some money and buy one pump and one filter. The money you save could pay for the second Intelliflo if/when this one dies.


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RE: Pump Configuration and Power Question

You certainly can turn this pool over once in 12 hours running one vs pump and filter, but your talking 100 gpm. That kind of defeats the purpose of having a VS pump.
The other thing is, depending on what is around your pool your single filter will clog faster, and need to be cleaned more.

I have a 65,000 gallon pool, and live in Scottsdale, so I have similar weather. So I speak with some level of experience. I have a duel setup on the pool and it works very well. You will save more in energy costs running two pumps slower then one on high. If something does happen to one side you have back up.

Looking at what you are building, I dont believe the upfront cost of two systems is a problem for you.

VF pumps are selling less, VS pumps are selling more.
Better to get one of the new IntellifloXF pumps. The wet ends blow the old style away, and is where all the pumps will eventually go. Cost is really no different.

Here is a link that might be useful: IntellifloXF


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