What diameter PVC for two 3/4" jets?

[AGrayson84]

Hi everyone, I'm brand new to the forum here and was hoping someone could give me some good input on my question.

Back-story:

We are redoing an above-ground pool that we have not ever used. The pool is 24'x15' (rectangular), and the walls are constructed of 3/4" treated plywood, so it's pretty easy to change some things around since we are putting new wall foam and a new liner in to give this pool a fresh start. The original owners of this house installed the skimmer and return jet approximately 3 ft from each other, so to correct this and help with the proper flow I plan on repositioning some stuff before the new liner goes in this weekend.

I've already bought a new skimmer and relocated it to the center of one of the 15' long walls. I now plan on installing two return jets on the opposite end of the pool to help push the water in the direction of the skimmer. The pump is on the side of the pool that has the skimmer, so I plan on running PVC piping to the new two new return jets on the opposite end of the skimmer/pump. The old return jet that I'm discarding had a 3/4" outlet.


The question:

The two new jets have a 3/4" outlet. So considering the length of the run of the pressure side that is going to have to go the jets (let's say approximately 37' to the furthest jet), what inside diameter of schedule 40 PVC pipe would allow for the optimal flow and pressure to the jets without being over-kill? I was thinking maybe about 1 1/4" might be good but I'm no expert in plumbing so I would really appreciate some feedback on what you all think may be a good choice. Thanks so much!-Andrew

 

[Bama Rambler]

Welcome to TFP.

First thing I'd change is the 3/4" eyeballs for 1" eyeballs. You should use 1½" wall return fittings so changing them in the future will be a non-issue.

Then I'd use 2" PVC plumbing everywhere.

 

[AGrayson84]

Hi Dave, thanks so much for the advice. Yeah I should be able to change out just the eyeballs later on the new jets once I get everything installed, but I won't have the time to get new ones between now and this weekend. The jets do have 1 1/2" return fittings and I have some brand new pool and spa hose to go between the jets and the PVC.

So, not to question your reasoning, I just want to pick up some education on this topic.... what's the reasoning for the suggestion of 2" piping leading to the jets? Again, I know nothing about pressure and flow, but I would have assumed that PVC of that diameter, running that distance, would kill the pressure getting to the jets.

Is the 2" to allow for enough flow for the distance, then the 1" eyeballs will "nozzle" the flow back down to create more pressure coming into the pool? Just trying to get some "learnin'" here

Thanks again!

 

[Bama Rambler]

2" plumbing will provide less restriction so you get more flow. You don't want the piping to create any more restriction than you have to. That way you get more flow into the pool. It's inverse to what you think. More pressure equals less flow and inversely less pressure equals more flow out of the same pump.

 

[AGrayson84]

Hey, that makes absolute sense with your explanation. Thanks so much for taking the time to help me understand! Any recommendation on approximately what height I should place these jets at?? The pool water level should be somewhere in the neighborhood of 40 inches. Not sure if I should put them at the same height (if so, half-way up the water level???) or if I should stagger the heights of them.

 

[Bama Rambler]

Probably about a foot under the water level should be fine.

 

[AGrayson84]

Thank you again, Sir!!!

 

[Speedo]

I would like to see an above ground made with plywood, is it designed more like an on-ground but in-ground style?

I like using the 1.5" pipes only because the attachments for my pool are all 1.5"

But with my pump on high I'm sure the piping is a bottleneck.

 

[AGrayson84]

Hey Speedo yeah it was, I assume, a custom-built above-ground pool. They basically framed out a box, put up the plywood walls, and built a deck around the top of the box. They used what looked like carpet padding for wall foam, did a sand floor, and just had a rectangular vinyl liner put in place. I'll take some pictures of it on Sunday and post them up here. Pretty simple setup though.