Closed pressurized solar heating system with automatic solar collector

Abstract

A closed pressurized solar heating system in which a solar collector is automatically drained of heat transport fluid independently of valve actuation or valve position. Undersized pipe return lines connect the solar collector to top, bottom and intermediate openings of a sump tank which is initially filled with the fluid, water, to a level between the top and intermediate openings. Drain-down automatically commences upon de-energization of a system pump, whereupon air from the top of the sump tank enters the pipe return line, breaking the vacuum existing within the flow path, and initiating fluid return to the sump tank. High flow rate embodiments with similarly automatic drain-down features are also disclosed. These embodiments employ flow diversion devices to divert fluid flow to undersized pipe return lines in communication with the sump tank during initial filling of the solar collector. After a predetermined time delay, fluid flow in the pipe return line is returned to oversized pipe sections which essentially bypass the sump tank and permit high flow rates.