With your 1/2" Pex, 50/50 mix, and loop at 272 feet (use about 281 feet, to account for 4 90 degree bends and a branch tee), calc is as follows:
H=0.0374*1.582*281*4.970 = 82.6 feet of head (using flow rate in 1/2" pex of 2.5 gpm, velocity slightly higher than 4 feet per second, none of the Taco...