What loop design software do you guys use? I seem to get a wide variation in the pipe required. For example for a 3.5 ton system if I use a single 1" pipe the trench would have to be 1680' long for a total of 1680' of pipe. If I use a verticle slinky setup the trench would need to be 690' long with a 1000' of pipe every 125' of trench for a total of 5440 feet of 1" pipe. Does anyone know why the difference would be so great in the amount of pipe needed?

Slinkies use less ground mass and require more pipe to keep the same EWT.

Each turn of a slinky coil is close enough to the last and the next so that they impact each other's bit of dirt