Abstract: A closed pressurized solar heating system in which a solar collector is automatically drained of heat transport fluid and which contains no mechanical moving parts other than a system circulating pump. Pipe lines connect the solar collector to top and bottom openings of a sump tank which is initially filled with the fluid, water, to a level intermediate between the top and bottom openings. The sump tank contains an internal pipe extending from the top opening of the tank down to below the operating level of the transport fluid, which is lower than the initial fill level because of the fluid required to fill the collector. Drain-back automatically commences upon de-energization of the system pump, whereupon air from the upper part of the sump tank enters a vent in the sump tank internal pipe, breaking the vacuum existing within the flow return path from the collector and initiating fluid return from the collector to the sump tank.

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.

Abstract: A solar heating collector assembly employing at least one collector panel which utilizes a collector plate formed of a plurality of long overlapping fins to absorb solar energy. Each absorber fin is coated with a substance having a predetermined selectivity and has soldered lengthwise thereto an absorber pipe in which a heat transport fluid is heated as the fluid circulates through the collector panel. The collector absorber plate is mounted on a collector frame over a plywood base having an aluminum foil vapor barrier covering the base. A double glazed glass assembly is mounted over the absorber plate and forms the top surface of the collector panel. The collector panel is disposed between a pair of installation tracks which define a pair of plumbing channels at opposite ends of the absorber pipes. Located within the plumbing channels are input and output pipe manifolds which are respectively connected to opposite ends of the absorber pipes.