First post, my question is focused on plumbing, I wasn't sure if I should post here or in the "construction" forum. I can redirect if need be. I'll be starting my owner-build in ground 16x30 gunite pool shortly, permit is in process. I have all my subs lined up, and am comfortable I've found a good source of equipment, materials, and subs. I'm a commercial general contractor myself, so the construction part of this is no concern. My question is in regards to the engineered drawings I purchased. I hired the firm that everyone around west central Florida uses, he's been reliable and affordable. On his TDH calcs, he states the branch piping is to be 4" (between the drains), trunk piping to be 3" (from the main drain T and skimmer back to the pump), and return piping to be 2.5" He spec'd the Pentair Intelliflo VS 3hp pump and what seems to be correctly calculated TDH and pipe sizes based on water velocities. But the drain he's spec'd only has 2.5" sockets to tie the 4" branch piping together. I called him to question using such large pipes when all the filter, pump, skimmer, return eye, etc only provide for 2" maximum pipe size. He stated he's been made to comply with ANSI requirements for water velocities of 6 feet per second branch, 8 fps trunk, and 10 fps for return, and that per the chart, these are the required pipe diameters for a pump that can pull 140 gpm based on the TDH.
To put it simply, does any of this make sense? I'm not hiring a pool builder because the construction part of this is simple for me. I'm struggling with accepting this engineering at face value-seems odd to increase from 2.5" to 4" and reduce back to 3" back to the pump.
To put it simply, does any of this make sense? I'm not hiring a pool builder because the construction part of this is simple for me. I'm struggling with accepting this engineering at face value-seems odd to increase from 2.5" to 4" and reduce back to 3" back to the pump.