Pool Opening Problems.

[PoolDoc]

Thanks, Mark.

Goose, given that the MAX flow -- for good filtration -- through a 24" filter, like the Tagelus 60, should be 45 GPM or less . . . it's safe to say that you are (1) wasting most of the pumping electricity you are consuming and (2) forcing the filter to fail. If you have 45 GPM on low, you shouldn't even turn the pump onto high, when you backwash.

[TheGoose]

So do you agree with my assessment that I have about ~50 ft of head on the pump and it's probably close to what the pump curve is?

[PoolDoc]

I haven't really checked -- I was just taking what you and Mark said, at face value.

For me to be comfortable estimating your TDH (total dynamic head), I'd want pictures of you skimmer(s), return(s), all equipment connections, pump, filter, valves & piping.

[mas985]

Return head is a know quantity from the filter pressure, ~49' of head. The only unknown is the suction head but as I posted before, that should be minimal because of the dual suction lines. I wouldn't expect more than a couple feet of head IF both lines are kept open all the time. If you want confirmation, I would need more details on the suction lines (diameters, lengths), number suction side valves, and the height of the pump above the pool water level. I can pretty guess the rest and get within 5%.

[PoolDoc]

My bad; should have scanned back for the pictures.

Using the Hazen-Williams calculator here, for the pipe between the pump and the filter (3xL; 1x branchT; 8' pipe => 20' equivalent length), I get a head loss of 9ft at 80gpm and 11ft at 90gpm. Using the Hayward chart I sent you, Mark, I calculate the drop through the dumb-head Tee layout as 3.5ft at 80 gpm and 4ft at 90 gpm. Estimating the equivalents lengths of the 1.5" piping to the pool at 50ft, and splitting flows evenly at 40gpm each and 45gpm each, I find a loss of 6 ft at 80gpm and 8ft at 90gpm

Taking filter pressure at 49ft, I estimate TDH around 57.5 ft @ 80 gpm(9+3.5+6=18.5) and 62 ft @ 90 gpm (11+4+8=23).

also used Charlotte Plastics Design manual

[Watermom]

Aren't you guys thankful for your math teachers!

[PoolDoc]

Honestly, I didn't learn to USE math until I was (a) taking engineering classes and (b) simultaneously doing repair work and realizing that I could use some of what I was learning in class to make my work easier.

[Watermom]

understand of how to use math in their daily lives.

That is something I talk about with my students every day. There is no reason to learn math unless you have a use for it. (Of course, some of my smarty-pants kids say then that they shouldn't have to learn it because they have no use for it!) Some day ..........

EDIT --- Rereading that it sounds backwards of what I was trying to imply but you guys know what I mean. My excuse for lack of clarity is that my mind is not on what I was writing right now cuz we are off to Baskin Robbins to get an ice cream cone!

[PoolDoc]

There is no reason to learn math unless you have a use for it. (Of course, some of my smarty-pants kids say then that they shouldn't have to learn it because they have no use for it!) Some day ..........

Make 'em do pool problems . . . !

Concentrations, ratios, flow rates, complex volume calculations (liner pools are easy, because they are all straight sides or radius curves, so bright middle school students possess the basic black-box tools to do the calcs), and so on.

[mas985]

Sorry, I was being a little lazy and not running full head calcs. I thought you were interested in an upper limit. But from the picture, it looks like the suction pipe is 2". So if you want full head calcs I need some additional information. If you have already given please post again so I have everything together:

Pump elevation relative to the water level (changes meaning of filter pressure)

Also, I don't remember reading the length of the suction runs. So how long are these and is the diameter 2"?

Filter pressure is 20 PSI correct?