Re: 4. "There are many active solar options that can be retrofitted to an existing greenhouse. .... Another option with this would be to plumb the black plastic water barrels together and make a closed system with the black plastic flexible piping in the peak and combine passive and active solar together to supplement the greenhouse heating. It would require a circulating pump that is run only during the day. I plan on enquiring into photoelectric cells to run the circulating pump."
It has been about 30 years since I was doing reading on closed loop passive solar collectors but I seem to remember that a circulating pump would not be needed. The heated water would gradually rise and then return as it cooled. At night the system would 'stop' when the system reached temperature equilibrium. Jerry in IN _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
