Pool plumbing advice 3in piping?

[pizzle85]

I am going to attempt to install my own in-ground fiberglass pool. For the most part i think i have it figured out but i'm looking for a bit more clarification on some specifics that relate to plumbing. I've read a great deal on this website already and have picked up the basics so i hope i'm asking the right questions.

I'm planning to install a 15000 gallon in ground fiberglass pool and a 1500 gallon in ground fiberglass hot tub. The hot tub will waterfall into the pool. The pool and the hot tub will have two main drains and a single skimmer on the pool. The suction from the main drains and skimmer on the pool will be about 100ft each. The main drains on the hot tub will be about 125ft. The returns for the pool will be about 100ft to the center of the loop and the hot tub will be about 125ft. Im planning on 4 pool return jets and 8 hot tub jets.

I am looking at purchasing the IntellifloXF. The fittings for this pump are 2 1/2in or 3in.

For this length of run does it make sense to use 3in pipe for as much plumbing as possible or should i stick with 2 or 2 1/2 or what?

When using this pump does it make sense to plumb 2in out of each main drain into a T that exits into a 3in pipe that runs 98ft of the 100ft run on the suction side? Does it make sense to do the same thing for the hot tub main drains?

The skimmer will have two 2in holes. Does it make sense to plumb the two of them together and T them into a 3in return pipe similar to the main drains?

The return side of the pump also has 2 1/2 or 3in fittings but i haven't found any other equipment (filter, heater, sanitizer,etc) that uses anything larger than 2in. Is it worth the time and possible cost to try to find equipment that have 3in fittings?

Because my returns are going to be 100 and 125 feet, would it make sense for me to go out of my sanitizer (my last piece of equipment before the pool) at 2in and convert back up to 3in for the entire loop of the return run then back down to 1 1/2 at the jets? or perhaps 3in on the return loop, to 2in at the T to the pool jet to 1 1/2 at the jet.

Does the way the suction lines are plumbed into the pump matter at all? I know i want as few bends as possible but does it matter if say the pool main drain comes directly into the pump while the skimmer and hot tub main drain come in on the sides and T into the pump?

 

[JasonLion]

Welcome to TFP!

Here are some things to think on:

The hot tub needs high flow rates, so larger pipe makes a much bigger difference to the hot tub.

3" fittings on equipment are extremely rare, and not especially important. Short sections of smaller pipe make only a tiny difference.

Typically you would have a couple of pipes between the pool and pad, drain and skimmer plumbed separately at a minimum. With two pipes you often go down a pipe size, as two smaller pipes are often as good as one larger pipe. Also you generally want the return pipe just slightly smaller than the suction pipe.

Spa mode is your high flow rate situation, so that would be the one you want straight in, not that it makes all that much difference (fraction of a percent).

IntelliFlo XF is only worth it if you really need the maximum flow rate for the spa (lots of jets). The regular IntelliFlo is more efficient at the lower flow rates used for the pool.

 

[pizzle85]

Thanks for the quick reply!

I've just been reading around a lot about head loss (http://www.pentairpool.com/pdfs/staritecommTM.pdf) and thought perhaps running a larger diameter pipe all around would allow me to run the pump at lower RPMs. In reality, i'm not sure how much difference 2 1/2 in vs 3in is going to give me.

I am planning on having three suction pipes: one for the two pool main drains, one for the pool skimmer and one for the hot tub main drains. I am also planning on having two return lines: one for the pool loop and one for the hot tub loop.

Judging from your comments it sounds like 2 1/2 in suction lines and 2in return lines are just fine for my use. And to go with the Intelliflo (likely VF) instead of the XF.