"Here is more detail. The single 10x40 collector is mounted horizontally on a south-facing first-floor roof. It is slightly elevated at the top to give it a proper angle for best winter efficiency. The roof faces about 15 degrees east of south, and I haven't chosen to compensate for this slight off-axis."
Hello Jason, do the riser tubes on your collector run horizontally or vertically? Most manufactures make their collectors with riser tubes running on the longer dimension of the collector. When mounting a collector horizontally, on a drain-back system, a consideration is to make sure the riser tubes are vertical as many years down the road, horizontal riser tubes will sag and this will create a place for water to pool and possible freeze.
