Sorry about the pic size. Hope to climb the learning curve on pic posting enough before the next one.
I actually used a small 110vac "utility" pump and a 5 gallon pail and got about 3 gallons/minute of flow. Basically didn't think a high flow rate would be necessary, but I imagine the elbows do give a lot of flow drag. I just wanted to fabricate a quick and cheap test unit using a sliding glass door (free in the newspaper) as the glazing, 2x6 sides, and a plywood back with insulation. I got approx a 2-3 temp rise across this thing (high noon in Vermont,June), which I think is around 3000 btu's/hr. Just curious what a "baseline" output has been seen on other units. Just starting to really research homebrew collectors, so any advice would be welcome.