Help figuring out flow for Intelliflo VS

[doncaruana]

Okay guys, I could really use a lot of help because I just had a brand new pool put in last fall (didn't get to swim until last week) and I think I may already know more than the builder - and I don't know diddley!

Anyway, I'm trying to figure what kind of flow I'm getting out of my Pentair Intelliflo VS. I only have a pool (no spa), but I've got a Pentair Mastertemp heater and a Pentair Clean and Clear cartridge-based filter (CCP240).

At 3110 RPM, the PSI on the filter was 18 and I was using about 1500 watts. At 2350 RPM, the PSI was down to 8 and about 700 watts.

Not sure how much more information I need or how much is even available, but any help is greatly appreciated.

Thanks!

 

[Melt In The Sun]

Some other info we'd need:
pipe size for suction/return lines and how many of each
an estimate of the length of those lines
height of the equipment relative to the water level

That being said, why is flow rate so important? I agree it fills a hole in your brain, but knowing it really doesn't serve any practical purpose!

 

[doncaruana]

I'm trying to figure out how much to run the pump to turn the pool over. I can't do that without knowing what the flow rate is, right? Or am I wrong about that?

The equipment is about 10 feet above water level and roughly 48 feet away. The lines are all 1.5", but I'm not sure how to count them. I have one skimmer and two floor drains in the deep part that I know are teed together. I guess the best way to put it is I have two valves - one for incoming and one for outgoing, so there are four lines going to the pool.

 

[JasonLion]

The correct amount of time to run the pump doesn't depend on turnovers, it depends on keeping the water looking good. Exactly how much of a turnover that requires varies from pool to pool and is best determined experimentally (instead of by trying to calculate flow rate).

 

[doncaruana]

Well, I'm flying completely blind right now. The builder left the pool running 24x7 at 3100RPM with the chlorinator and the heater on. After I pointed out that the chlorinator wasn't running and they mucked with that, the pool is looking wonderful. However, since they didn't even hook up the pump or heater (and didn't realize it) and I already had to show them how to program the lights, I have nothing to go on. I was hoping for at least a target and then I can tweak from there. I've never owned a pool before so I have no past experience to pull from. I'd kind of like to tune things down a bit and not run everything so much more than necessary for the sake of both the equipment and my utility bills.

 

[JasonLion]

What kind of pool surface do you have? For plaster you need to leave the pump on 24/7 at a reasonable speed for the first while. With plaster I would only turn down the pump to around 2000 RPM and leave it on 24/7.

If you don't have plaster, start experimenting with finding the lowest speed the pump can run at where the skimmers still work well. Typically that is around 1200 RPM, but it varies quite a bit.

It would help if you put your basic pool specs in your signature.

 

[doncaruana]

Sorry - like I said, new pool owner.

Using a couple of other signatures as an example, would this be right?
16K gal, vinyl rectangle (sport dig), Intelliflo VS, 240 sqft cartridge filter, Intellichlor IC40, Mastertemp 250, Dolphin supreme M4 cleaning robot

 

[JasonLion]

Yes, that sample signature looks great.

For a vinyl pool, in addition to playing with lower speeds, you can cut the run time to 12 hours a day right away, and then experiment with even shorter run times after that.

Because of the SWG, the minimum pump speed also needs to be enough to keep the SWG happy along with the skimmers.

 

[mas985]

The equipment is about 10 feet above water level and roughly 48 feet away.

The pump has a 10' lift? Are you seeing any air in the pump basket?

Also, you said there was a valve for both the suction and return. What is that valve for?

 

[doncaruana]

Are you seeing any air in the pump basket?

Um...what exactly does that mean? When I look at the little window in the top of the pump, I think I see air and water swishing around, but it's kind of hard to tell.

Yes - there is a 10' lift.

There is one valve for each direction.

For the returns, the valve switches been the two main drains in the bottom (which are teed to the same line) and the skimmer.

On the outflow, the valve switches between the jets (there are 2) and the deck jets (also two).

 

[mas985]

The 10 foot lift will have a lot of suction head (> 10') which can draw in air if the lid is not sealed well so sometimes you will see air in the pump basket which it sounds like you do.

So do you normally keep both valves in the center position so there is flow from both the skimmer and main drain and flow to both return ports?

Also, the filter PSI you posted earlier, what was the valve position for the suction and return lines (i.e. was anything shut off)?


Note: Just so we are on the same page when it comes to definitions, pool terms are opposite of HVAC terms. Returns are from the pump to the pool (pressure side of the pump). Suction is from the pool to the pump (skimmers, main drains, etc).

 

[doncaruana]

Thanks for the continuing education.

Right now (as in when I did the PSI) the return is almost fully on the pool jets and the suction is all through the skimmer (the drains are off).

 

[mas985]

The problem I am having is that to get the wattage down to the level that you are seeing, I have to add a lot of suction side head loss.

Can you describe your suction side plumbing in a bit more detail if you can and is there anything you can think of that would cause extra suction side head loss?

Also, can you take another filter pressure measurement with both the skimmer and main drain fully open (valve set mid-way)?

A picture of your equipment pad might help too.

BTW, this is a perfect example why I pulled the spreadsheet. There are cases like this when things just don't seem to add up and need a bit more work to figure out what is going on.

 

[doncaruana]

Well I might be a little low on the elevation - but I don't think it's as high as 15 feet. Do you count elevation from the water surface level?

Suction side...there is a big tee with the two main drains going into one 1.5" pipe (I watched them pour over that). Don't know anything about the skimmer except that it also is a 1.5" pipe. The two lines go up the slope and come up out of the ground into a 3 way valve right next to the equipment pad. Sort of like a big upside down U with a tail where the tail is 90 degrees from the rest and goes a few inches to step-up fitting to 2" (because the VS actually has 2" fittings").

That's all I can think of for now.

I'll do some pressure stuff and also a picture when I get home from work later (in about 4 hours).

 

[doncaruana]

Okay...the 10 foot elevation is right on - or at least within a few inches. That's from the water surface to the pump inlet.

I've got 21 psi with the suction valve in the middle (skimmer and drains all open) and 1621 watts at 3110 rpm. Here's a picture of the pad and also one of the pump "window". I think that means there's a lot of air in it. When I went to look at it it suddenly lost pressure (or whatever it is) and there was no water in the pump basket. The skimmer was pretty full (the drains were off at this point), but even after emptying it and opening the drains, it wouldn't fill back up until after I turned it off for a few minutes.

The lower valve is the return (set almost completely to the pool jets) and the upper one is the suction lines (set in the middle).

 

[mas985]

It would seem as the pump is behaving as though there is a lot of head loss too so maybe there really is. The lift is pretty significant adding 10' of head by itself plus the long runs. I would leave both ports open for normal operation or you may starve the pump and cause problems like you are seeing.

Anyway I am getting close to an answer and have just a few more questions that your pictures sparked.

Can you describe the plumbing/fittings that go around the backside of the filter? I can't tell what is going on and looks like there is a line that is teed off that line.

Also, how big are the two eyeballs in the pool returns?

 

[doncaruana]

Actually that's just a makeshift stand to support the pipe. The pipe you see to the right of the filter just goes around the back, over the makeshift support and then to the front of the filter.

As far as the eyeballs, I'm not positive, but I think they are only 1.5", maybe 2 at most. I'd measure them but it's dark and the mosquitos will eat me alive! lol. Here's the model of the deck jets: http://www.pentairpool.com/pool-pro/products/water-features-deck-jet-deck-jet-ii-36.htm.

 

[mas985]

I think am I am about as close as I am going to get on this. The pool jets must be 1/2" to get the pressure and wattage you are seeing so I am going to assume that is what you actually have. Anyway, the flow rate with both suction ports open should be about 51.5 GPM @ 3110 RPM or a formula of RPM / 60.4. I would suggest running this way most of the time but if you close off one of the suction runs, the flow rate will drop to 48.7 GPM @ 3110 RPM or a formula of RPM / 63.9. But that is probably why you are getting so much air in the pump.

Sorry it took so long to get to an answer but you have a very unique setup.

 

[doncaruana]

Took so long? Are you kidding?? That was fast if you ask me!!

I do have another question though - will that RPM/60.4 hold at a lower RPM level? The reason I ask is I'd like to lower the speed a little and I only need to get to about 33 GPM to turn the pool over in 8 hours. That would put me at an RPM level of about 2000. Or is that a whole different curve?

Thanks SO much for all your help!!!

 

[mas985]

RPM / 60.4 should hold for all RPM although the error tends to grow a little bit as RPM is lowered.