New variable pump-- turnover time hard to believe..

[coreyoreo]

Hi, all...

So I installed a new Pentair Variable pump, model 11018, all works fine except...

According to the pentair site, they say if I run my pump @1000rpm for 17 hrs, that will be one complete turnover. (Pool size is 17,000 gals.)

I have it running at that exact setting now, but geezo... it sure looks to me like hardly any water at all is flowing out of my spillover spa, and the filters/lines aren't clogged. Hard to believe that 17,000 gals will turn over in 17 hours.

Does this seem correct? Is this what I should expect? Or am I just used to the single speed 3450rpm pump's turnover time?

Thanks for any opinions...
Corey

 

[JamesW]

17,000 gallons will turn over in 17 hours at about 17 GPM. 17 GPM does not seem like a lot of flow compared to a standard pump running at full speed. 17 GPM is about double what a garden hose will do.

 

[JasonLion]

The flow rate estimates at the Pentair site are just estimates. The actual flow rate depends on many details of your plumbing. In any case, it is very plausible that you are getting 17 GPM at 1000 RPM. Most pools get more than 17 GPM at 1000 RPM.

 

[mas985]

These are some rough estimates that I have come up with for various types/sizes of plumbing:

Intelliflo/EcoStar on 1.5" Plumbing with 1 Suction Line: Flow Rate (GPM) = RPM / 45
Intelliflo/EcoStar on 1.5" Plumbing with 2 Suction Line: Flow Rate (GPM) = RPM / 40
Intelliflo/EcoStar on 2.0" Plumbing with 1 Suction Line: Flow Rate (GPM) = RPM / 35
Intelliflo/EcoStar on 2.0" Plumbing with 2 Suction Line: Flow Rate (GPM) = RPM / 30
Intelliflo/EcoStar on 2.5" Plumbing with 1 Suction Line: Flow Rate (GPM) = RPM / 30
Intelliflo/EcoStar on 2.5" Plumbing with 2 Suction Line: Flow Rate (GPM) = RPM / 25

The Pentair estimate is far lower than the worst of these. At 1000 RPM, I would think you would be at least at 20 GPM and problably closer to 25 GPM.

 

[coreyoreo]

Thanks, James, Jason & Mas985

I have a 12" wide breakaway on the spa wall & it just looks (to me, anyway) like MAYBE 2-3 GPM, if that, is spilling over... I don't know any other way to judge the flow rate.

I also have one 2" suction line, but if I'm not mistaken, the original plumbing in and around this older pool is 1.5", so somewhere underground is the 2" to 1.5" adapter, I would assume it's near the pump.

I bumped it up to 1800rpm this morning & now it looks more like 17 gpm now. Still not sure though.

Is there a more accurate way to measure it?

 

[JamesW]

You could get a flowmeter.

What is the filter pressure at various speeds?

http://www.bluwhite.com/Products/Variab ... ctpage.asp

 

[coreyoreo]

Various Filter PSI Pressure:

750rpm: 0 (no reading)
1000rpm: 0 (no reading)
1800rpm: 8
3110rpm: 20
3450rpm: 25

Normal PSI with old pump (single speed 1.5hp 3450rpm) was consistently 20-22. In fact, even with filters removed pressure was 20-22.

 

[mas985]

How high is the filter gauge relative to the pool water?

Also, do you have multiple suction lines or only a single suction line from the pool all the way to the equipment?

 

[coreyoreo]

Filter gauge is probably 5-6 feet above water level.

There's one suction line, divided by a jandy valve that's usually positioned to get water from the skimmer, which is about 45 feet away from the pump.

Here's a pic:

 

[mas985]

Assuming that the suction line is 1.5" all the way from the pool and with the additional information above, I get:

GPM = RPM / 54

or about 19 GPM @ 1000 RPM.

At full speed, is the pump drawing in a lot of air?

 

[coreyoreo]

Not at high speed as far as I can tell, Mark. However, at 1000 rpm, an air bubble appears in the strainer after a few hours.

But when the pump starts at the next scheduled time, it primes itself at high speed and in just a few seconds the bubble disappears. I guess it's supposed to do that.

Heck.. if it's 19gpm @ 1000rpm, I'll turn it back again.

Thanks for your help, mark

 

[JamesW]

I can't tell for sure, but the plumbing all looks like 2-inch PVC.

 

[mas985]

I also have one 2" suction line, but if I'm not mistaken, the original plumbing in and around this older pool is 1.5", so somewhere underground is the 2" to 1.5" adapter,I would assume it's near the pump.

 

[JamesW]

I also have one 2" suction line, but if I'm not mistaken, the original plumbing in and around this older pool is 1.5", so somewhere underground is the 2" to 1.5" adapter,I would assume it's near the pump.

OK, thanks, I missed that part.

 

[coreyoreo]

Yes, I'm assuming that there's a 2" to 1.5" adapter on the 2 inlet & the 2 outlet lines, probably near the pump when the previous pump was installed before I moved in.

I'm assuming because that's the diameter of the skimmer suction port.

Corey

 

[JamesW]

Yes, I'm assuming that there's a 2" to 1.5" adapter on the 2 inlet & the 2 outlet lines, probably near the pump when the previous pump was installed before I moved in.

I'm assuming because that's the diameter of the skimmer suction port.

Corey

Not necessarily, it's possible that the plumbing is all 2-inch except for the connections to the pool.

 

[coreyoreo]

Ah, ok. Thank you.

I guess I'll never really know for sure unless I ever need to dig them up.

Was it normal to use 1.5" plumbing in older pools?

 

[JamesW]

1.5 inch and 2-inch are common.

I don't think that 1.5 inch should be used on an inground pool, especially on suction.