Sizing looped return line

[Project]

Hi there
I am hoping someone can suggest the size PVC to use for three one sided returns on a loop. Cored return lines to pool are 2 inch, what pipe do you experienced folk recommend looping with? My equipment pad is within a few metres of the return, everything is nice and compact. I was thinking of sticking with 2 inch but read somewhere this loop pipe should be bigger?
Thanks!!
Paul

 

[mas985]

If you use a larger pipe, you won't need a loop. The reason for the loop is because there is pressure loss between the first and last return and that is due to the loss in the pipe. But if the pipe is large, 2.5" or even 3", then the pressure difference between the returns will be minimal. BTW, what is the distance between the first and last return? 2" might not have all that much loss either if the run is short.

 

[jtech1]

When I designed mine out, besides tons of advice form on here, I just made sure the cross sectional area of the main was somewhere near the combination of what I was feeding in to it.

Most returns are usually 1.5"... I would probably base it on 1.5 returns at normal return flow rate... in my pool when two were tied together I used 2". If I were tying three together I would have probably run 2.5". Unless you want to crank as much as you can through the 2" returns... then you should probably use 3" main so the combined velocity is similar to what it would be in each of the 2" returns individually.

The return pairs I had tied together (seat backs) were within a few feet from each other and the PB ran a stub a couple feet past each one and T'ed into the returns also... said this would help make sure the flow is even. The T was right in th middle between them so I think that running past them was probably not necessary in this case, but in the event they were far apart and the supply hit one before the other, and one was at the end of the line, I am guessing that is where running past it, or better yet, a loop would help. My 3 bubblers were run on a 1.5" loop fed with 2.5". Each one can flow 30 gpm... so the 2.5 can flow about 90gpm at around 6 fps.

 

[Project]

Thanks guys
The distance is short between the first and the last return, about 3 metres. The pool isnt huge, but I just want to try and get it right the first time. Perhaps a 3" run shooting off to the 2" would be ok then? As there is very little pipe, it would'nt be a pain at all if the best way would be to loop in 2".

 

[mas985]

A 3" header would be my preference and would probably work better than a 2" loop too.

BTW, I am not sure it is all that important to have equal flow out of the returns anyway. You just don't want a huge difference.

 

[Project]

Ok, thanks very much for your advice. It's been most helpful.