Tubing layout patterns

DaveA

Looking at tubing layout patterns for my 1200 SF slab on grade shop floor. I will have four 300' circuits of 1/2" PEX, each covering a space of 15' x 20'. I've seen examples with the serpentine pattern where the tube starts following the outer perimeter of its space and continues in a concentric pattern. With this pattern the turns are only 90 deg. until it reaches the center. The other pattern I've seen has the tubing running left to right continuously. So with this pattern each side to side run makes a 180 deg. turn at each end. I know from my experience laying out dust collector ducting that it is best to avoid 90 deg. turns and 180 deg turns just don't happen. The reason being that each turn provides additional resistance to the air flow, cutting down the CFM. I haven't seen any info on whether multiple turns in a hydronic tubing layout have a similar effect on flow or pressure. So the question to the pros here is whether the serpentine layout is more desirable than the side to side for that reason or is the difference negligible?
Thanks.

Big Ed_4

Use wide sweeps on the turns...

GroundUp

The issue I see with a lot of serpentine layouts is that they run a single loop around the majority of the perimeter, aka the coldest part of the slab, which brings return temps on that loop far below usable level and results in colder floors along the exterior walls. In a 4 loop setup like yours, I would limit exterior wall exposure to 1 wall per loop, and the hottest water adjacent to the coldest part of the slab (perimeter). I always start clockwise from the manifold and run the length of the first exterior wall, then 180 back and forth until distance is met. Second loop would run right inside the return run of the first loop and fill in the center that way until the opposite wall you started with, which ends up as a mirror image of the first loop. Keeps all loop temperatures fairly even by keeping exterior exposure even