I am from Warwick, Rhode Island
I have 4 hot air collectors in operation at my house. I also built my own solar hot water drainback system that has been functioning perfectly since day 1.
My solar hot water drainback system not only heats the water in a storage tank prior to entering my electric hot water heater but it also heats a 45 gallon tank that I use for home heating by pumping that stored hot water out to a 15 foot Runtal radiator in my large family room.
So far so good, but lots to tweek with the hot air collectors.
I've actually disconnected 2 vertical air flow style hot air collectors because of frigid cold air backdraft reasons.
My latest built horizontal air flow hot air collectors do not present the same frigid backdraft issues as the vertical air flow models so they are still connected and running.
If anyone wants a PDF file showing how I built my latest horizontal air flow style hot air collectors, my solar hot water drainback system or my DIY backdraft dampers (that really work well) contact me anytime and I'd be more than happy to send you the PDFs via EMAIL.