What makes me nervous. The connectors are simple, squeezed rubber grommets pushed into a saw-bit drilled hole in the 1.5" headers. Leaks can normally be fixed by simply jiggling the tubing. Make sure that a coil that receives water first from the cold header has its return connected to the warm header last, and vice versa. I.e. a coil that is closest to the pool pump on the cold header is furthest from the pool jets on the return (warm) header. Tubing length in all coils should be close to identical, no matter whether a coil is round or oval. What is important is that the length of flow through the narrow tubing is identical in all coils. If adequate care is not taken for such simple rules then one could end up with a short circuit wherein most of the water goes through only a few, not all coils. Similarly if there is a slope to the roof, make sure that the inlet header is on the lower side and the outlet header on the higher side, to better prevent air locks. In all cases make sure that the warm water rises higher than all the coils before going to the pool. This imposes some back pressure that forces the cold water to actually go through all the coils. At the highest point put in a vacuum-release (also called an air-release) valve to let air out when the coils are filling in early morning, and air in when the coils are emptying at the end of the day.